Commit Graph

67 Commits

Author SHA1 Message Date
Arve Hjønnevåg ef73d6a4ef sched/wait: Fix a kthread_park race with wait_woken()
kthread_park and wait_woken have a similar race that
kthread_stop and wait_woken used to have before it was fixed in
commit cb6538e740 ("sched/wait: Fix a kthread race with
wait_woken()"). Extend that fix to also cover kthread_park.

[jstultz: Made changes suggested by Peter to optimize
 memory loads]

Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20230602212350.535358-1-jstultz@google.com
2023-06-16 17:08:01 +02:00
Christoph Hellwig f624506f98 kthread: unexport kthread_blkcg
kthread_blkcg is only used by the built-in blk-cgroup code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220420042723.1010598-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-02 14:06:20 -06:00
Rasmus Villemoes 62eb29526b linux/kthread.h: remove unused macros
Ever since these macros were introduced in commit b56c0d8937
("kthread: implement kthread_worker"), there has been precisely one user
(commit 4d11542070, "NVMe: Async IO queue deletion"), and that user
went away in 2016 with db3cbfff5b ("NVMe: IO queue deletion
re-write").

Apart from being unused, these macros are also awkward to use (which may
contribute to them not being used): Having a way to statically (or
on-stack) allocating the storage for the struct kthread_worker itself
doesn't help much, since obviously one needs to have some code for
actually _spawning_ the worker thread, which must have error checking.
And these days we have the kthread_create_worker() interface which both
allocates the struct kthread_worker and spawns the kthread.

Link: https://lkml.kernel.org/r/20220314145343.494694-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Cai Huoqing <caihuoqing@baidu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-22 15:57:00 -07:00
Linus Torvalds f4484d138b Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
 "55 patches.

  Subsystems affected by this patch series: percpu, procfs, sysctl,
  misc, core-kernel, get_maintainer, lib, checkpatch, binfmt, nilfs2,
  hfs, fat, adfs, panic, delayacct, kconfig, kcov, and ubsan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (55 commits)
  lib: remove redundant assignment to variable ret
  ubsan: remove CONFIG_UBSAN_OBJECT_SIZE
  kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR
  lib/Kconfig.debug: make TEST_KMOD depend on PAGE_SIZE_LESS_THAN_256KB
  btrfs: use generic Kconfig option for 256kB page size limit
  arch/Kconfig: split PAGE_SIZE_LESS_THAN_256KB from PAGE_SIZE_LESS_THAN_64KB
  configs: introduce debug.config for CI-like setup
  delayacct: track delays from memory compact
  Documentation/accounting/delay-accounting.rst: add thrashing page cache and direct compact
  delayacct: cleanup flags in struct task_delay_info and functions use it
  delayacct: fix incomplete disable operation when switch enable to disable
  delayacct: support swapin delay accounting for swapping without blkio
  panic: remove oops_id
  panic: use error_report_end tracepoint on warnings
  fs/adfs: remove unneeded variable make code cleaner
  FAT: use io_schedule_timeout() instead of congestion_wait()
  hfsplus: use struct_group_attr() for memcpy() region
  nilfs2: remove redundant pointer sbufs
  fs/binfmt_elf: use PT_LOAD p_align values for static PIE
  const_structs.checkpatch: add frequently used ops structs
  ...
2022-01-20 10:41:01 +02:00
Yafang Shao d6986ce24f kthread: dynamically allocate memory to store kthread's full name
When I was implementing a new per-cpu kthread cfs_migration, I found the
comm of it "cfs_migration/%u" is truncated due to the limitation of
TASK_COMM_LEN.  For example, the comm of the percpu thread on CPU10~19
all have the same name "cfs_migration/1", which will confuse the user.
This issue is not critical, because we can get the corresponding CPU
from the task's Cpus_allowed.  But for kthreads corresponding to other
hardware devices, it is not easy to get the detailed device info from
task comm, for example,

    jbd2/nvme0n1p2-
    xfs-reclaim/sdf

Currently there are so many truncated kthreads:

    rcu_tasks_kthre
    rcu_tasks_rude_
    rcu_tasks_trace
    poll_mpt3sas0_s
    ext4-rsv-conver
    xfs-reclaim/sd{a, b, c, ...}
    xfs-blockgc/sd{a, b, c, ...}
    xfs-inodegc/sd{a, b, c, ...}
    audit_send_repl
    ecryptfs-kthrea
    vfio-irqfd-clea
    jbd2/nvme0n1p2-
    ...

We can shorten these names to work around this problem, but it may be
not applied to all of the truncated kthreads.  Take 'jbd2/nvme0n1p2-'
for example, it is a nice name, and it is not a good idea to shorten it.

One possible way to fix this issue is extending the task comm size, but
as task->comm is used in lots of places, that may cause some potential
buffer overflows.  Another more conservative approach is introducing a
new pointer to store kthread's full name if it is truncated, which won't
introduce too much overhead as it is in the non-critical path.  Finally
we make a dicision to use the second approach.  See also the discussions
in this thread:
https://lore.kernel.org/lkml/20211101060419.4682-1-laoar.shao@gmail.com/

After this change, the full name of these truncated kthreads will be
displayed via /proc/[pid]/comm:

    rcu_tasks_kthread
    rcu_tasks_rude_kthread
    rcu_tasks_trace_kthread
    poll_mpt3sas0_statu
    ext4-rsv-conversion
    xfs-reclaim/sdf1
    xfs-blockgc/sdf1
    xfs-inodegc/sdf1
    audit_send_reply
    ecryptfs-kthread
    vfio-irqfd-cleanup
    jbd2/nvme0n1p2-8

Link: https://lkml.kernel.org/r/20211120112850.46047-1-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-20 08:52:53 +02:00
Linus Torvalds 35ce8ae9ae Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull signal/exit/ptrace updates from Eric Biederman:
 "This set of changes deletes some dead code, makes a lot of cleanups
  which hopefully make the code easier to follow, and fixes bugs found
  along the way.

  The end-game which I have not yet reached yet is for fatal signals
  that generate coredumps to be short-circuit deliverable from
  complete_signal, for force_siginfo_to_task not to require changing
  userspace configured signal delivery state, and for the ptrace stops
  to always happen in locations where we can guarantee on all
  architectures that the all of the registers are saved and available on
  the stack.

  Removal of profile_task_ext, profile_munmap, and profile_handoff_task
  are the big successes for dead code removal this round.

  A bunch of small bug fixes are included, as most of the issues
  reported were small enough that they would not affect bisection so I
  simply added the fixes and did not fold the fixes into the changes
  they were fixing.

  There was a bug that broke coredumps piped to systemd-coredump. I
  dropped the change that caused that bug and replaced it entirely with
  something much more restrained. Unfortunately that required some
  rebasing.

  Some successes after this set of changes: There are few enough calls
  to do_exit to audit in a reasonable amount of time. The lifetime of
  struct kthread now matches the lifetime of struct task, and the
  pointer to struct kthread is no longer stored in set_child_tid. The
  flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
  removed. Issues where task->exit_code was examined with
  signal->group_exit_code should been examined were fixed.

  There are several loosely related changes included because I am
  cleaning up and if I don't include them they will probably get lost.

  The original postings of these changes can be found at:
     https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org
     https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org

  I trimmed back the last set of changes to only the obviously correct
  once. Simply because there was less time for review than I had hoped"

* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
  ptrace/m68k: Stop open coding ptrace_report_syscall
  ptrace: Remove unused regs argument from ptrace_report_syscall
  ptrace: Remove second setting of PT_SEIZED in ptrace_attach
  taskstats: Cleanup the use of task->exit_code
  exit: Use the correct exit_code in /proc/<pid>/stat
  exit: Fix the exit_code for wait_task_zombie
  exit: Coredumps reach do_group_exit
  exit: Remove profile_handoff_task
  exit: Remove profile_task_exit & profile_munmap
  signal: clean up kernel-doc comments
  signal: Remove the helper signal_group_exit
  signal: Rename group_exit_task group_exec_task
  coredump: Stop setting signal->group_exit_task
  signal: Remove SIGNAL_GROUP_COREDUMP
  signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
  signal: Make coredump handling explicit in complete_signal
  signal: Have prepare_signal detect coredumps using signal->core_state
  signal: Have the oom killer detect coredumps using signal->core_state
  exit: Move force_uaccess back into do_exit
  exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
  ...
2022-01-17 05:49:30 +02:00
Cai Huoqing 800977f6f3 kthread: add the helper function kthread_run_on_cpu()
Add a new helper function kthread_run_on_cpu(), which includes
kthread_create_on_cpu/wake_up_process().

In some cases, use kthread_run_on_cpu() directly instead of
kthread_create_on_node/kthread_bind/wake_up_process() or
kthread_create_on_cpu/wake_up_process() or
kthreadd_create/kthread_bind/wake_up_process() to simplify the code.

[akpm@linux-foundation.org: export kthread_create_on_cpu to modules]

Link: https://lkml.kernel.org/r/20211022025711.3673-2-caihuoqing@baidu.com
Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Cc: Bernard Metzler <bmt@zurich.ibm.com>
Cc: Cai Huoqing <caihuoqing@baidu.com>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-15 16:30:23 +02:00
Eric W. Biederman 40966e316f kthread: Ensure struct kthread is present for all kthreads
Today the rules are a bit iffy and arbitrary about which kernel
threads have struct kthread present.  Both idle threads and thread
started with create_kthread want struct kthread present so that is
effectively all kernel threads.  Make the rule that if PF_KTHREAD
and the task is running then struct kthread is present.

This will allow the kernel thread code to using tsk->exit_code
with different semantics from ordinary processes.

To make ensure that struct kthread is present for all
kernel threads move it's allocation into copy_process.

Add a deallocation of struct kthread in exec for processes
that were kernel threads.

Move the allocation of struct kthread for the initial thread
earlier so that it is not repeated for each additional idle
thread.

Move the initialization of struct kthread into set_kthread_struct
so that the structure is always and reliably initailized.

Clear set_child_tid in free_kthread_struct to ensure the kthread
struct is reliably freed during exec.  The function
free_kthread_struct does not need to clear vfork_done during exec as
exec_mm_release called from exec_mmap has already cleared vfork_done.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman cead185526 exit: Rename complete_and_exit to kthread_complete_and_exit
Update complete_and_exit to call kthread_exit instead of do_exit.

Change the name to reflect this change in functionality.  All of the
users of complete_and_exit are causing the current kthread to exit so
this change makes it clear what is happening.

Move the implementation of kthread_complete_and_exit from
kernel/exit.c to to kernel/kthread.c.  As this function is kthread
specific it makes most sense to live with the kthread functions.

There are no functional change.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Eric W. Biederman bbda86e988 exit: Implement kthread_exit
The way the per task_struct exit_code is used by kernel threads is not
quite compatible how it is used by userspace applications.  The low
byte of the userspace exit_code value encodes the exit signal.  While
kthreads just use the value as an int holding ordinary kernel function
exit status like -EPERM.

Add kthread_exit to clearly separate the two kinds of uses.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-12-13 12:04:45 -06:00
Linus Torvalds 65090f30ab Merge branch 'akpm' (patches from Andrew)
Merge misc updates from Andrew Morton:
 "191 patches.

  Subsystems affected by this patch series: kthread, ia64, scripts,
  ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
  slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
  mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
  pagealloc, and memory-failure)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
  mm,hwpoison: make get_hwpoison_page() call get_any_page()
  mm,hwpoison: send SIGBUS with error virutal address
  mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
  mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
  mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
  mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
  docs: remove description of DISCONTIGMEM
  arch, mm: remove stale mentions of DISCONIGMEM
  mm: remove CONFIG_DISCONTIGMEM
  m68k: remove support for DISCONTIGMEM
  arc: remove support for DISCONTIGMEM
  arc: update comment about HIGHMEM implementation
  alpha: remove DISCONTIGMEM and NUMA
  mm/page_alloc: move free_the_page
  mm/page_alloc: fix counting of managed_pages
  mm/page_alloc: improve memmap_pages dbg msg
  mm: drop SECTION_SHIFT in code comments
  mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
  mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
  mm/page_alloc: scale the number of pages that are batch freed
  ...
2021-06-29 17:29:11 -07:00
Jonathan Neuschäfer 20ce0c2d5a kthread: switch to new kerneldoc syntax for named variable macro argument
The syntax without dots is available since commit 43756e347f
("scripts/kernel-doc: Add support for named variable macro arguments").

The same HTML output is produced with and without this patch.

Link: https://lkml.kernel.org/r/20210513161702.1721039-1-j.neuschaefer@gmx.net
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29 10:53:45 -07:00
Valentin Schneider 00b89fe019 sched: Make the idle task quack like a per-CPU kthread
For all intents and purposes, the idle task is a per-CPU kthread. It isn't
created via the same route as other pcpu kthreads however, and as a result
it is missing a few bells and whistles: it fails kthread_is_per_cpu() and
it doesn't have PF_NO_SETAFFINITY set.

Fix the former by giving the idle task a kthread struct along with the
KTHREAD_IS_PER_CPU flag. This requires some extra iffery as init_idle()
call be called more than once on the same idle task.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210510151024.2448573-2-valentin.schneider@arm.com
2021-05-18 12:53:53 +02:00
Peter Zijlstra ac687e6e8c kthread: Extract KTHREAD_IS_PER_CPU
There is a need to distinguish geniune per-cpu kthreads from kthreads
that happen to have a single CPU affinity.

Geniune per-cpu kthreads are kthreads that are CPU affine for
correctness, these will obviously have PF_KTHREAD set, but must also
have PF_NO_SETAFFINITY set, lest userspace modify their affinity and
ruins things.

However, these two things are not sufficient, PF_NO_SETAFFINITY is
also set on other tasks that have their affinities controlled through
other means, like for instance workqueues.

Therefore another bit is needed; it turns out kthread_create_per_cpu()
already has such a bit: KTHREAD_IS_PER_CPU, which is used to make
kthread_park()/kthread_unpark() work correctly.

Expose this flag and remove the implicit setting of it from
kthread_create_on_cpu(); the io_uring usage of it seems dubious at
best.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210121103506.557620262@infradead.org
2021-01-22 15:09:42 +01:00
Linus Torvalds 623f6dc593 Merge branch 'akpm' (patches from Andrew)
Merge some more updates from Andrew Morton:

 - various hotfixes and minor things

 - hch's use_mm/unuse_mm clearnups

Subsystems affected by this patch series: mm/hugetlb, scripts, kcov,
lib, nilfs, checkpatch, lib, mm/debug, ocfs2, lib, misc.

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  kernel: set USER_DS in kthread_use_mm
  kernel: better document the use_mm/unuse_mm API contract
  kernel: move use_mm/unuse_mm to kthread.c
  kernel: move use_mm/unuse_mm to kthread.c
  stacktrace: cleanup inconsistent variable type
  lib: test get_count_order/long in test_bitops.c
  mm: add comments on pglist_data zones
  ocfs2: fix spelling mistake and grammar
  mm/debug_vm_pgtable: fix kernel crash by checking for THP support
  lib: fix bitmap_parse() on 64-bit big endian archs
  checkpatch: correct check for kernel parameters doc
  nilfs2: fix null pointer dereference at nilfs_segctor_do_construct()
  lib/lz4/lz4_decompress.c: document deliberate use of `&'
  kcov: check kcov_softirq in kcov_remote_stop()
  scripts/spelling: add a few more typos
  khugepaged: selftests: fix timeout condition in wait_for_scan()
2020-06-11 13:25:53 -07:00
Christoph Hellwig f5678e7f2a kernel: better document the use_mm/unuse_mm API contract
Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).

Also give the functions a kthread_ prefix to better document the use case.

[hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
  Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de
[sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename]
  Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
Acked-by: Haren Myneni <haren@linux.ibm.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-10 19:14:18 -07:00
Christoph Hellwig 9bf5b9eb23 kernel: move use_mm/unuse_mm to kthread.c
Patch series "improve use_mm / unuse_mm", v2.

This series improves the use_mm / unuse_mm interface by better documenting
the assumptions, and my taking the set_fs manipulations spread over the
callers into the core API.

This patch (of 3):

Use the proper API instead.

Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de

These helpers are only for use with kernel threads, and I will tie them
more into the kthread infrastructure going forward.  Also move the
prototypes to kthread.h - mmu_context.h was a little weird to start with
as it otherwise contains very low-level MM bits.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200416053158.586887-1-hch@lst.de
Link: http://lkml.kernel.org/r/20200404094101.672954-5-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-10 19:14:18 -07:00
J. Bruce Fields 52782c92ac kthread: save thread function
It's handy to keep the kthread_fn just as a unique cookie to identify
classes of kthreads.  E.g. if you can verify that a given task is
running your thread_fn, then you may know what sort of type kthread_data
points to.

We'll use this in nfsd to pass some information into the vfs.  Note it
will need kthread_data() exported too.

Original-patch-by: Tejun Heo <tj@kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-05-08 21:23:10 -04:00
Petr Mladek 98c985d7da kthread: mark timer used by delayed kthread works as IRQ safe
The timer used by delayed kthread works are IRQ safe because the used
kthread_delayed_work_timer_fn() is IRQ safe.

It is properly marked when initialized by KTHREAD_DELAYED_WORK_INIT().
But TIMER_IRQSAFE flag is missing when initialized by
kthread_init_delayed_work().

The missing flag might trigger invalid warning from del_timer_sync() when
kthread_mod_delayed_work() is called with interrupts disabled.

This patch is result of a discussion about using the API, see
https://lkml.kernel.org/r/cfa886ad-e3b7-c0d2-3ff8-58d94170eab5@ti.com

Reported-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200217120709.1974-1-pmladek@suse.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 09:35:25 -07:00
Suren Baghdasaryan 8af0c18af1 include/: refactor headers to allow kthread.h inclusion in psi_types.h
kthread.h can't be included in psi_types.h because it creates a circular
inclusion with kthread.h eventually including psi_types.h and
complaining on kthread structures not being defined because they are
defined further in the kthread.h.  Resolve this by removing psi_types.h
inclusion from the headers included from kthread.h.

Link: http://lkml.kernel.org/r/20190319235619.260832-7-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 19:52:48 -07:00
Linus Torvalds 45802da05e Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - refcount conversions

   - Solve the rq->leaf_cfs_rq_list can of worms for real.

   - improve power-aware scheduling

   - add sysctl knob for Energy Aware Scheduling

   - documentation updates

   - misc other changes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
  kthread: Do not use TIMER_IRQSAFE
  kthread: Convert worker lock to raw spinlock
  sched/fair: Use non-atomic cpumask_{set,clear}_cpu()
  sched/fair: Remove unused 'sd' parameter from select_idle_smt()
  sched/wait: Use freezable_schedule() when possible
  sched/fair: Prune, fix and simplify the nohz_balancer_kick() comment block
  sched/fair: Explain LLC nohz kick condition
  sched/fair: Simplify nohz_balancer_kick()
  sched/topology: Fix percpu data types in struct sd_data & struct s_data
  sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
  sched/fair: Fix O(nr_cgroups) in the load balancing path
  sched/fair: Optimize update_blocked_averages()
  sched/fair: Fix insertion in rq->leaf_cfs_rq_list
  sched/fair: Add tmp_alone_branch assertion
  sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
  sched/debug: Initialize sd_sysctl_cpus if !CONFIG_CPUMASK_OFFSTACK
  sched/pelt: Skip updating util_est when utilization is higher than CPU's capacity
  sched/fair: Update scale invariance of PELT
  sched/fair: Move the rq_of() helper function
  sched/core: Convert task_struct.stack_refcount to refcount_t
  ...
2019-03-06 08:14:05 -08:00
Sebastian Andrzej Siewior ad01423aed kthread: Do not use TIMER_IRQSAFE
The TIMER_IRQSAFE usage was introduced in commit 22597dc3d9 ("kthread:
initial support for delayed kthread work") which modelled the delayed
kthread code after workqueue's code. The workqueue code requires the flag
TIMER_IRQSAFE for synchronisation purpose. This is not true for kthread's
delay timer since all operations occur under a lock.

Remove TIMER_IRQSAFE from the timer initialisation and use timer_setup()
for initialisation purpose which is the official function.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lkml.kernel.org/r/20190212162554.19779-2-bigeasy@linutronix.de
2019-02-28 11:18:38 +01:00
Julia Cartwright fe99a4f4d6 kthread: Convert worker lock to raw spinlock
In order to enable the queuing of kthread work items from hardirq context
even when PREEMPT_RT_FULL is enabled, convert the worker spin_lock to a
raw_spin_lock.

This is only acceptable to do because the work performed under the lock is
well-bounded and minimal.

Reported-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reported-by: Tim Sander <tim@krieglstein.org>
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Link: https://lkml.kernel.org/r/20190212162554.19779-1-bigeasy@linutronix.de
2019-02-28 11:18:38 +01:00
Matthias Kaehlcke 0121805d9d kthread: Add __kthread_should_park()
kthread_should_park() is used to check if the calling kthread ('current')
should park, but there is no function to check whether an arbitrary kthread
should be parked. The latter is required to plug a CPU hotplug race vs. a
parking ksoftirqd thread.

The new __kthread_should_park() receives a task_struct as parameter to
check if the corresponding kernel thread should be parked.

Call __kthread_should_park() from kthread_should_park() to avoid code
duplication.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Link: https://lkml.kernel.org/r/20190128234625.78241-2-mka@chromium.org
2019-02-10 21:51:39 +01:00
Peter Zijlstra 1cef1150ef kthread, sched/core: Fix kthread_parkme() (again...)
Gaurav reports that commit:

  85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")

isn't working for him. Because of the following race:

> controller Thread                               CPUHP Thread
> takedown_cpu
> kthread_park
> kthread_parkme
> Set KTHREAD_SHOULD_PARK
>                                                 smpboot_thread_fn
>                                                 set Task interruptible
>
>
> wake_up_process
>  if (!(p->state & state))
>                 goto out;
>
>                                                 Kthread_parkme
>                                                 SET TASK_PARKED
>                                                 schedule
>                                                 raw_spin_lock(&rq->lock)
> ttwu_remote
> waiting for __task_rq_lock
>                                                 context_switch
>
>                                                 finish_lock_switch
>
>
>
>                                                 Case TASK_PARKED
>                                                 kthread_park_complete
>
>
> SET Running

Furthermore, Oleg noticed that the whole scheduler TASK_PARKED
handling is buggered because the TASK_DEAD thing is done with
preemption disabled, the current code can still complete early on
preemption :/

So basically revert that earlier fix and go with a variant of the
alternative mentioned in the commit. Promote TASK_PARKED to special
state to avoid the store-store issue on task->state leading to the
WARN in kthread_unpark() -> __kthread_bind().

But in addition, add wait_task_inactive() to kthread_park() to ensure
the task really is PARKED when we return from kthread_park(). This
avoids the whole kthread still gets migrated nonsense -- although it
would be really good to get this done differently.

Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 85f1abe001 ("kthread, sched/wait: Fix kthread_parkme() completion issue")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-03 09:17:30 +02:00
Peter Zijlstra 85f1abe001 kthread, sched/wait: Fix kthread_parkme() completion issue
Even with the wait-loop fixed, there is a further issue with
kthread_parkme(). Upon hotplug, when we do takedown_cpu(),
smpboot_park_threads() can return before all those threads are in fact
blocked, due to the placement of the complete() in __kthread_parkme().

When that happens, sched_cpu_dying() -> migrate_tasks() can end up
migrating such a still runnable task onto another CPU.

Normally the task will have hit schedule() and gone to sleep by the
time we do kthread_unpark(), which will then do __kthread_bind() to
re-bind the task to the correct CPU.

However, when we loose the initial TASK_PARKED store to the concurrent
wakeup issue described previously, do the complete(), get migrated, it
is possible to either:

 - observe kthread_unpark()'s clearing of SHOULD_PARK and terminate
   the park and set TASK_RUNNING, or

 - __kthread_bind()'s wait_task_inactive() to observe the competing
   TASK_RUNNING store.

Either way the WARN() in __kthread_bind() will trigger and fail to
correctly set the CPU affinity.

Fix this by only issuing the complete() when the kthread has scheduled
out. This does away with all the icky 'still running' nonsense.

The alternative is to promote TASK_PARKED to a special state, this
guarantees wait_task_inactive() cannot observe a 'stale' TASK_RUNNING
and we'll end up doing the right thing, but this preserves the whole
icky business of potentially migating the still runnable thing.

Reported-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-03 07:38:05 +02:00
Kees Cook 841b86f328 treewide: Remove TIMER_FUNC_TYPE and TIMER_DATA_TYPE casts
With all callbacks converted, and the timer callback prototype
switched over, the TIMER_FUNC_TYPE cast is no longer needed,
so remove it. Conversion was done with the following scripts:

    perl -pi -e 's|\(TIMER_FUNC_TYPE\)||g' \
        $(git grep TIMER_FUNC_TYPE | cut -d: -f1 | sort -u)

    perl -pi -e 's|\(TIMER_DATA_TYPE\)||g' \
        $(git grep TIMER_DATA_TYPE | cut -d: -f1 | sort -u)

The now unused macros are also dropped from include/linux/timer.h.

Signed-off-by: Kees Cook <keescook@chromium.org>
2017-11-21 16:35:54 -08:00
Kees Cook 919b250f85 timer: Remove redundant __setup_timer*() macros
With __init_timer*() now matching __setup_timer*(), remove the redundant
internal interface, clean up the resulting definitions and add more
documentation.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
2017-11-21 15:57:15 -08:00
Kees Cook 1fe66ba572 timer: Remove unused data arguments from macros
With the .data field removed, the ignored data arguments in timer macros
can be removed.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2017-11-21 15:57:14 -08:00
Linus Torvalds e2c5923c34 Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block
Pull core block layer updates from Jens Axboe:
 "This is the main pull request for block storage for 4.15-rc1.

  Nothing out of the ordinary in here, and no API changes or anything
  like that. Just various new features for drivers, core changes, etc.
  In particular, this pull request contains:

   - A patch series from Bart, closing the whole on blk/scsi-mq queue
     quescing.

   - A series from Christoph, building towards hidden gendisks (for
     multipath) and ability to move bio chains around.

   - NVMe
        - Support for native multipath for NVMe (Christoph).
        - Userspace notifications for AENs (Keith).
        - Command side-effects support (Keith).
        - SGL support (Chaitanya Kulkarni)
        - FC fixes and improvements (James Smart)
        - Lots of fixes and tweaks (Various)

   - bcache
        - New maintainer (Michael Lyle)
        - Writeback control improvements (Michael)
        - Various fixes (Coly, Elena, Eric, Liang, et al)

   - lightnvm updates, mostly centered around the pblk interface
     (Javier, Hans, and Rakesh).

   - Removal of unused bio/bvec kmap atomic interfaces (me, Christoph)

   - Writeback series that fix the much discussed hundreds of millions
     of sync-all units. This goes all the way, as discussed previously
     (me).

   - Fix for missing wakeup on writeback timer adjustments (Yafang
     Shao).

   - Fix laptop mode on blk-mq (me).

   - {mq,name} tupple lookup for IO schedulers, allowing us to have
     alias names. This means you can use 'deadline' on both !mq and on
     mq (where it's called mq-deadline). (me).

   - blktrace race fix, oopsing on sg load (me).

   - blk-mq optimizations (me).

   - Obscure waitqueue race fix for kyber (Omar).

   - NBD fixes (Josef).

   - Disable writeback throttling by default on bfq, like we do on cfq
     (Luca Miccio).

   - Series from Ming that enable us to treat flush requests on blk-mq
     like any other request. This is a really nice cleanup.

   - Series from Ming that improves merging on blk-mq with schedulers,
     getting us closer to flipping the switch on scsi-mq again.

   - BFQ updates (Paolo).

   - blk-mq atomic flags memory ordering fixes (Peter Z).

   - Loop cgroup support (Shaohua).

   - Lots of minor fixes from lots of different folks, both for core and
     driver code"

* 'for-4.15/block' of git://git.kernel.dk/linux-block: (294 commits)
  nvme: fix visibility of "uuid" ns attribute
  blk-mq: fixup some comment typos and lengths
  ide: ide-atapi: fix compile error with defining macro DEBUG
  blk-mq: improve tag waiting setup for non-shared tags
  brd: remove unused brd_mutex
  blk-mq: only run the hardware queue if IO is pending
  block: avoid null pointer dereference on null disk
  fs: guard_bio_eod() needs to consider partitions
  xtensa/simdisk: fix compile error
  nvme: expose subsys attribute to sysfs
  nvme: create 'slaves' and 'holders' entries for hidden controllers
  block: create 'slaves' and 'holders' entries for hidden gendisks
  nvme: also expose the namespace identification sysfs files for mpath nodes
  nvme: implement multipath access to nvme subsystems
  nvme: track shared namespaces
  nvme: introduce a nvme_ns_ids structure
  nvme: track subsystems
  block, nvme: Introduce blk_mq_req_flags_t
  block, scsi: Make SCSI quiesce and resume work reliably
  block: Add the QUEUE_FLAG_PREEMPT_ONLY request queue flag
  ...
2017-11-14 15:32:19 -08:00
Linus Torvalds 2bcc673101 Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
 "Yet another big pile of changes:

   - More year 2038 work from Arnd slowly reaching the point where we
     need to think about the syscalls themself.

   - A new timer function which allows to conditionally (re)arm a timer
     only when it's either not running or the new expiry time is sooner
     than the armed expiry time. This allows to use a single timer for
     multiple timeout requirements w/o caring about the first expiry
     time at the call site.

   - A new NMI safe accessor to clock real time for the printk timestamp
     work. Can be used by tracing, perf as well if required.

   - A large number of timer setup conversions from Kees which got
     collected here because either maintainers requested so or they
     simply got ignored. As Kees pointed out already there are a few
     trivial merge conflicts and some redundant commits which was
     unavoidable due to the size of this conversion effort.

   - Avoid a redundant iteration in the timer wheel softirq processing.

   - Provide a mechanism to treat RTC implementations depending on their
     hardware properties, i.e. don't inflict the write at the 0.5
     seconds boundary which originates from the PC CMOS RTC to all RTCs.
     No functional change as drivers need to be updated separately.

   - The usual small updates to core code clocksource drivers. Nothing
     really exciting"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (111 commits)
  timers: Add a function to start/reduce a timer
  pstore: Use ktime_get_real_fast_ns() instead of __getnstimeofday()
  timer: Prepare to change all DEFINE_TIMER() callbacks
  netfilter: ipvs: Convert timers to use timer_setup()
  scsi: qla2xxx: Convert timers to use timer_setup()
  block/aoe: discover_timer: Convert timers to use timer_setup()
  ide: Convert timers to use timer_setup()
  drbd: Convert timers to use timer_setup()
  mailbox: Convert timers to use timer_setup()
  crypto: Convert timers to use timer_setup()
  drivers/pcmcia: omap1: Fix error in automated timer conversion
  ARM: footbridge: Fix typo in timer conversion
  drivers/sgi-xp: Convert timers to use timer_setup()
  drivers/pcmcia: Convert timers to use timer_setup()
  drivers/memstick: Convert timers to use timer_setup()
  drivers/macintosh: Convert timers to use timer_setup()
  hwrng/xgene-rng: Convert timers to use timer_setup()
  auxdisplay: Convert timers to use timer_setup()
  sparc/led: Convert timers to use timer_setup()
  mips: ip22/32: Convert timers to use timer_setup()
  ...
2017-11-13 17:56:58 -08:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Kees Cook fe5c3b69b5 kthread: Convert callback to use from_timer()
In preparation for unconditionally passing the struct timer_list pointer
to all timer callbacks, switch kthread to use from_timer() and pass the
timer pointer explicitly.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mips@linux-mips.org
Cc: Len Brown <len.brown@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux1394-devel@lists.sourceforge.net
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pm@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Gross <mark.gross@intel.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Michael Reed <mdr@sgi.com>
Cc: netdev@vger.kernel.org
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lkml.kernel.org/r/1507159627-127660-13-git-send-email-keescook@chromium.org
2017-10-05 15:01:22 +02:00
Kees Cook 8ede369b2c timer: Remove expires argument from __TIMER_INITIALIZER()
The expires field is normally initialized during the first mod_timer()
call. It was unused by all callers, so remove it from the macro.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: linux-mips@linux-mips.org
Cc: Petr Mladek <pmladek@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Kalle Valo <kvalo@qca.qualcomm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux1394-devel@lists.sourceforge.net
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: linux-s390@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ursula Braun <ubraun@linux.vnet.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Reed <mdr@sgi.com>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pm@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Gross <mark.gross@intel.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: netdev@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lkml.kernel.org/r/1507159627-127660-12-git-send-email-keescook@chromium.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-10-05 15:01:21 +02:00
Shaohua Li 0b508bc926 block: fix a build error
The code is only for blkcg not for all cgroups

Fixes: d4478e92d6 ("block/loop: make loop cgroup aware")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-26 12:07:24 -06:00
Shaohua Li 05e3db95eb kthread: add a mechanism to store cgroup info
kthread usually runs jobs on behalf of other threads. The jobs should be
charged to cgroup of original threads. But the jobs run in a kthread,
where we lose the cgroup context of original threads. The patch adds a
machanism to record cgroup info of original threads in kthread context.
Later we can retrieve the cgroup info and attach the cgroup info to jobs.

Since this mechanism is only required by kthread, we store the cgroup
info in kthread data instead of generic task_struct.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-09-26 07:41:22 -06:00
Jonathan Corbet d16977f3a6 kthread: fix documentation build warning
The kerneldoc comment for kthread_create() had an incorrect argument
name, leading to a warning in the docs build.

Correct it, and make one more small step toward a warning-free build.

Link: http://lkml.kernel.org/r/20170724135916.7f486c6f@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-02 16:34:47 -07:00
Nicolas Iooss c0b942a763 kthread: add __printf attributes
When commit fbae2d44aa ("kthread: add kthread_create_worker*()")
introduced some kthread_create_...() functions which were taking
printf-like parametter, it introduced __printf attributes to some
functions (e.g.  kthread_create_worker()).  Nevertheless some new
functions were forgotten (they have been detected thanks to
-Wmissing-format-attribute warning flag).

Add the missing __printf attributes to the newly-introduced functions in
order to detect formatting issues at build-time with -Wformat flag.

Link: http://lkml.kernel.org/r/20161126193543.22672-1-nicolas.iooss_linux@m4x.org
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12 18:55:06 -08:00
Oleg Nesterov 1da5c46fa9 kthread: Make struct kthread kmalloc'ed
commit 23196f2e5f "kthread: Pin the stack via try_get_task_stack() /
put_task_stack() in to_live_kthread() function" is a workaround for the
fragile design of struct kthread being allocated on the task stack.

struct kthread in its current form should be removed, but this needs
cleanups outside of kthread.c.

As a first step move struct kthread away from the task stack by making it
kmalloc'ed. This allows to access kthread.exited without the magic of
trying to pin task stack and the try logic in to_live_kthread().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chunming Zhou <David1.Zhou@amd.com>
Cc: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20161129175057.GA5330@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-08 14:36:18 +01:00
Jonathan Corbet e154ccc831 kthread: add kerneldoc for kthread_create()
This macro is referenced in other kerneldoc comments, but lacks one of its
own; fix that.

Link: http://lkml.kernel.org/r/20160826072313.726a3485@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Reported-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek dbf52682cb kthread: better support freezable kthread workers
This patch allows to make kthread worker freezable via a new @flags
parameter. It will allow to avoid an init work in some kthreads.

It currently does not affect the function of kthread_worker_fn()
but it might help to do some optimization or fixes eventually.

I currently do not know about any other use for the @flags
parameter but I believe that we will want more flags
in the future.

Finally, I hope that it will not cause confusion with @flags member
in struct kthread. Well, I guess that we will want to rework the
basic kthreads implementation once all kthreads are converted into
kthread workers or workqueues. It is possible that we will merge
the two structures.

Link: http://lkml.kernel.org/r/1470754545-17632-12-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek 9a6b06c8d9 kthread: allow to modify delayed kthread work
There are situations when we need to modify the delay of a delayed kthread
work. For example, when the work depends on an event and the initial delay
means a timeout. Then we want to queue the work immediately when the event
happens.

This patch implements kthread_mod_delayed_work() as inspired workqueues.
It cancels the timer, removes the work from any worker list and queues it
again with the given timeout.

A very special case is when the work is being canceled at the same time.
It might happen because of the regular kthread_cancel_delayed_work_sync()
or by another kthread_mod_delayed_work(). In this case, we do nothing and
let the other operation win. This should not normally happen as the caller
is supposed to synchronize these operations a reasonable way.

Link: http://lkml.kernel.org/r/1470754545-17632-11-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek 37be45d49d kthread: allow to cancel kthread work
We are going to use kthread workers more widely and sometimes we will need
to make sure that the work is neither pending nor running.

This patch implements cancel_*_sync() operations as inspired by
workqueues.  Well, we are synchronized against the other operations via
the worker lock, we use del_timer_sync() and a counter to count parallel
cancel operations.  Therefore the implementation might be easier.

First, we check if a worker is assigned.  If not, the work has newer been
queued after it was initialized.

Second, we take the worker lock.  It must be the right one.  The work must
not be assigned to another worker unless it is initialized in between.

Third, we try to cancel the timer when it exists.  The timer is deleted
synchronously to make sure that the timer call back is not running.  We
need to temporary release the worker->lock to avoid a possible deadlock
with the callback.  In the meantime, we set work->canceling counter to
avoid any queuing.

Fourth, we try to remove the work from a worker list. It might be
the list of either normal or delayed works.

Fifth, if the work is running, we call kthread_flush_work().  It might
take an arbitrary time.  We need to release the worker-lock again.  In the
meantime, we again block any queuing by the canceling counter.

As already mentioned, the check for a pending kthread work is done under a
lock.  In compare with workqueues, we do not need to fight for a single
PENDING bit to block other operations.  Therefore we do not suffer from
the thundering storm problem and all parallel canceling jobs might use
kthread_flush_work().  Any queuing is blocked until the counter gets zero.

Link: http://lkml.kernel.org/r/1470754545-17632-10-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek 22597dc3d9 kthread: initial support for delayed kthread work
We are going to use kthread_worker more widely and delayed works
will be pretty useful.

The implementation is inspired by workqueues.  It uses a timer to queue
the work after the requested delay.  If the delay is zero, the work is
queued immediately.

In compare with workqueues, each work is associated with a single worker
(kthread).  Therefore the implementation could be much easier.  In
particular, we use the worker->lock to synchronize all the operations with
the work.  We do not need any atomic operation with a flags variable.

In fact, we do not need any state variable at all.  Instead, we add a list
of delayed works into the worker.  Then the pending work is listed either
in the list of queued or delayed works.  And the existing check of pending
works is the same even for the delayed ones.

A work must not be assigned to another worker unless reinitialized.
Therefore the timer handler might expect that dwork->work->worker is valid
and it could simply take the lock.  We just add some sanity checks to help
with debugging a potential misuse.

Link: http://lkml.kernel.org/r/1470754545-17632-9-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek 35033fe9cb kthread: add kthread_destroy_worker()
The current kthread worker users call flush() and stop() explicitly.
This function does the same plus it frees the kthread_worker struct
in one call.

It is supposed to be used together with kthread_create_worker*() that
allocates struct kthread_worker.

Link: http://lkml.kernel.org/r/1470754545-17632-7-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek fbae2d44aa kthread: add kthread_create_worker*()
Kthread workers are currently created using the classic kthread API,
namely kthread_run().  kthread_worker_fn() is passed as the @threadfn
parameter.

This patch defines kthread_create_worker() and
kthread_create_worker_on_cpu() functions that hide implementation details.

They enforce using kthread_worker_fn() for the main thread.  But I doubt
that there are any plans to create any alternative.  In fact, I think that
we do not want any alternative main thread because it would be hard to
support consistency with the rest of the kthread worker API.

The naming and function of kthread_create_worker() is inspired by the
workqueues API like the rest of the kthread worker API.

The kthread_create_worker_on_cpu() variant is motivated by the original
kthread_create_on_cpu().  Note that we need to bind per-CPU kthread
workers already when they are created.  It makes the life easier.
kthread_bind() could not be used later for an already running worker.

This patch does _not_ convert existing kthread workers.  The kthread
worker API need more improvements first, e.g.  a function to destroy the
worker.

IMPORTANT:

kthread_create_worker_on_cpu() allows to use any format of the worker
name, in compare with kthread_create_on_cpu().  The good thing is that it
is more generic.  The bad thing is that most users will need to pass the
cpu number in two parameters, e.g.  kthread_create_worker_on_cpu(cpu,
"helper/%d", cpu).

To be honest, the main motivation was to avoid the need for an empty
va_list.  The only legal way was to create a helper function that would be
called with an empty list.  Other attempts caused compilation warnings or
even errors on different architectures.

There were also other alternatives, for example, using #define or
splitting __kthread_create_worker().  The used solution looked like the
least ugly.

Link: http://lkml.kernel.org/r/1470754545-17632-6-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek 3989144f86 kthread: kthread worker API cleanup
A good practice is to prefix the names of functions by the name
of the subsystem.

The kthread worker API is a mix of classic kthreads and workqueues.  Each
worker has a dedicated kthread.  It runs a generic function that process
queued works.  It is implemented as part of the kthread subsystem.

This patch renames the existing kthread worker API to use
the corresponding name from the workqueues API prefixed by
kthread_:

__init_kthread_worker()		-> __kthread_init_worker()
init_kthread_worker()		-> kthread_init_worker()
init_kthread_work()		-> kthread_init_work()
insert_kthread_work()		-> kthread_insert_work()
queue_kthread_work()		-> kthread_queue_work()
flush_kthread_work()		-> kthread_flush_work()
flush_kthread_worker()		-> kthread_flush_worker()

Note that the names of DEFINE_KTHREAD_WORK*() macros stay
as they are. It is common that the "DEFINE_" prefix has
precedence over the subsystem names.

Note that INIT() macros and init() functions use different
naming scheme. There is no good solution. There are several
reasons for this solution:

  + "init" in the function names stands for the verb "initialize"
    aka "initialize worker". While "INIT" in the macro names
    stands for the noun "INITIALIZER" aka "worker initializer".

  + INIT() macros are used only in DEFINE() macros

  + init() functions are used close to the other kthread()
    functions. It looks much better if all the functions
    use the same scheme.

  + There will be also kthread_destroy_worker() that will
    be used close to kthread_cancel_work(). It is related
    to the init() function. Again it looks better if all
    functions use the same naming scheme.

  + there are several precedents for such init() function
    names, e.g. amd_iommu_init_device(), free_area_init_node(),
    jump_label_init_type(),  regmap_init_mmio_clk(),

  + It is not an argument but it was inconsistent even before.

[arnd@arndb.de: fix linux-next merge conflict]
 Link: http://lkml.kernel.org/r/20160908135724.1311726-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/1470754545-17632-3-git-send-email-pmladek@suse.com
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Petr Mladek e700591ae0 kthread: rename probe_kthread_data() to kthread_probe_data()
Patch series "kthread: Kthread worker API improvements"

The intention of this patchset is to make it easier to manipulate and
maintain kthreads.  Especially, I want to replace all the custom main
cycles with a generic one.  Also I want to make the kthreads sleep in a
consistent state in a common place when there is no work.

This patch (of 11):

A good practice is to prefix the names of functions by the name of the
subsystem.

This patch fixes the name of probe_kthread_data().  The other wrong
functions names are part of the kthread worker API and will be fixed
separately.

Link: http://lkml.kernel.org/r/1470754545-17632-2-git-send-email-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Andrew Morton e9f069868d kernel/kthread.c:kthread_create_on_node(): clarify documentation
- Make it clear that the `node' arg refers to memory allocations only:
  kthread_create_on_node() does not pin the new thread to that node's
  CPUs.

- Encourage the use of NUMA_NO_NODE.

[nzimmer@sgi.com: use NUMA_NO_NODE in kthread_create() also]
Cc: Nathan Zimmer <nzimmer@sgi.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Peter Zijlstra 25834c73f9 sched: Fix a race between __kthread_bind() and sched_setaffinity()
Because sched_setscheduler() checks p->flags & PF_NO_SETAFFINITY
without locks, a caller might observe an old value and race with the
set_cpus_allowed_ptr() call from __kthread_bind() and effectively undo
it:

	__kthread_bind()
	  do_set_cpus_allowed()
						<SYSCALL>
						  sched_setaffinity()
						    if (p->flags & PF_NO_SETAFFINITIY)
						    set_cpus_allowed_ptr()
	  p->flags |= PF_NO_SETAFFINITY

Fix the bug by putting everything under the regular scheduler locks.

This also closes a hole in the serialization of task_struct::{nr_,}cpus_allowed.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dedekind1@gmail.com
Cc: juri.lelli@arm.com
Cc: mgorman@suse.de
Cc: riel@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20150515154833.545640346@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-08-12 12:06:09 +02:00