Implement debugging for kobject release functions. kobjects are
reference counted, so the drop of the last reference to them is not
predictable. However, the common case is for the last reference to be
the kobject's removal from a subsystem, which results in the release
function being immediately called.
This can hide subtle bugs, which can occur when another thread holds a
reference to the kobject at the same time that a kobject is removed.
This results in the release method being delayed.
In order to make these kinds of problems more visible, the following
patch implements a delayed release; this has the effect that the
release function will be out of order with respect to the removal of
the kobject in the same manner that it would be if a reference was
being held.
This provides us with an easy way to allow driver writers to debug
their drivers and fix otherwise hidden problems.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the uses of the __cpuinit macros from C files in
the core kernel directories (kernel, init, lib, mm, and include)
that don't really have a specific maintainer.
[1] https://lkml.org/lkml/2013/5/20/589
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Pull more vfs stuff from Al Viro:
"O_TMPFILE ABI changes, Oleg's fput() series, misc cleanups, including
making simple_lookup() usable for filesystems with non-NULL s_d_op,
which allows us to get rid of quite a bit of ugliness"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
sunrpc: now we can just set ->s_d_op
cgroup: we can use simple_lookup() now
efivarfs: we can use simple_lookup() now
make simple_lookup() usable for filesystems that set ->s_d_op
configfs: don't open-code d_alloc_name()
__rpc_lookup_create_exclusive: pass string instead of qstr
rpc_create_*_dir: don't bother with qstr
llist: llist_add() can use llist_add_batch()
llist: fix/simplify llist_add() and llist_add_batch()
fput: turn "list_head delayed_fput_list" into llist_head
fs/file_table.c:fput(): add comment
Safer ABI for O_TMPFILE
Pull core locking updates from Thomas Gleixner:
"Header cleanup as requested by Linus"
(This is the "don't include support for ww_mutex in a header file that
everybody wants, when almost nobody wants the ww part" change)
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
mutex: Move ww_mutex definitions to ww_mutex.h
Pull MIPS updates from Ralf Baechle:
"MIPS updates:
- All the things that didn't make 3.10.
- Removes the Windriver PPMC platform. Nobody will miss it.
- Remove a workaround from kernel/irq/irqdomain.c which was there
exclusivly for MIPS. Patch by Grant Likely.
- More small improvments for the SEAD 3 platform
- Improvments on the BMIPS / SMP support for the BCM63xx series.
- Various cleanups of dead leftovers.
- Platform support for the Cavium Octeon-based EdgeRouter Lite.
Two large KVM patchsets didn't make it for this pull request because
their respective authors are vacationing"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (124 commits)
MIPS: Kconfig: Add missing MODULES dependency to VPE_LOADER
MIPS: BCM63xx: CLK: Add dummy clk_{set,round}_rate() functions
MIPS: SEAD3: Disable L2 cache on SEAD-3.
MIPS: BCM63xx: Enable second core SMP on BCM6328 if available
MIPS: BCM63xx: Add SMP support to prom.c
MIPS: define write{b,w,l,q}_relaxed
MIPS: Expose missing pci_io{map,unmap} declarations
MIPS: Malta: Update GCMP detection.
Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"
MIPS: APSP: Remove <asm/kspd.h>
SSB: Kconfig: Amend SSB_EMBEDDED dependencies
MIPS: microMIPS: Fix improper definition of ISA exception bit.
MIPS: Don't try to decode microMIPS branch instructions where they cannot exist.
MIPS: Declare emulate_load_store_microMIPS as a static function.
MIPS: Fix typos and cleanup comment
MIPS: Cleanup indentation and whitespace
MIPS: BMIPS: support booting from physical CPU other than 0
MIPS: Only set cpu_has_mmips if SYS_SUPPORTS_MICROMIPS
MIPS: GIC: Fix gic_set_affinity infinite loop
MIPS: Don't save/restore OCTEON wide multiplier state on syscalls.
...
1. This is mostly theoretical, but llist_add*() need ACCESS_ONCE().
Otherwise it is not guaranteed that the first cmpxchg() uses the
same value for old_entry and new_last->next.
2. These helpers cache the result of cmpxchg() and read the initial
value of head->first before the main loop. I do not think this
makes sense. In the likely case cmpxchg() succeeds, otherwise
it doesn't hurt to reload head->first.
I think it would be better to simplify the code and simply read
->first before cmpxchg().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Move the definitions for wound/wait mutexes out to a separate
header, ww_mutex.h. This reduces clutter in mutex.h, and
increases readability.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Dave Airlie <airlied@gmail.com>
Link: http://lkml.kernel.org/r/51D675DC.3000907@canonical.com
[ Tidied up the code a bit. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull networking updates from David Miller:
"This is a re-do of the net-next pull request for the current merge
window. The only difference from the one I made the other day is that
this has Eliezer's interface renames and the timeout handling changes
made based upon your feedback, as well as a few bug fixes that have
trickeled in.
Highlights:
1) Low latency device polling, eliminating the cost of interrupt
handling and context switches. Allows direct polling of a network
device from socket operations, such as recvmsg() and poll().
Currently ixgbe, mlx4, and bnx2x support this feature.
Full high level description, performance numbers, and design in
commit 0a4db187a9 ("Merge branch 'll_poll'")
From Eliezer Tamir.
2) With the routing cache removed, ip_check_mc_rcu() gets exercised
more than ever before in the case where we have lots of multicast
addresses. Use a hash table instead of a simple linked list, from
Eric Dumazet.
3) Add driver for Atheros CQA98xx 802.11ac wireless devices, from
Bartosz Markowski, Janusz Dziedzic, Kalle Valo, Marek Kwaczynski,
Marek Puzyniak, Michal Kazior, and Sujith Manoharan.
4) Support reporting the TUN device persist flag to userspace, from
Pavel Emelyanov.
5) Allow controlling network device VF link state using netlink, from
Rony Efraim.
6) Support GRE tunneling in openvswitch, from Pravin B Shelar.
7) Adjust SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF for modern times, from
Daniel Borkmann and Eric Dumazet.
8) Allow controlling of TCP quickack behavior on a per-route basis,
from Cong Wang.
9) Several bug fixes and improvements to vxlan from Stephen
Hemminger, Pravin B Shelar, and Mike Rapoport. In particular,
support receiving on multiple UDP ports.
10) Major cleanups, particular in the area of debugging and cookie
lifetime handline, to the SCTP protocol code. From Daniel
Borkmann.
11) Allow packets to cross network namespaces when traversing tunnel
devices. From Nicolas Dichtel.
12) Allow monitoring netlink traffic via AF_PACKET sockets, in a
manner akin to how we monitor real network traffic via ptype_all.
From Daniel Borkmann.
13) Several bug fixes and improvements for the new alx device driver,
from Johannes Berg.
14) Fix scalability issues in the netem packet scheduler's time queue,
by using an rbtree. From Eric Dumazet.
15) Several bug fixes in TCP loss recovery handling, from Yuchung
Cheng.
16) Add support for GSO segmentation of MPLS packets, from Simon
Horman.
17) Make network notifiers have a real data type for the opaque
pointer that's passed into them. Use this to properly handle
network device flag changes in arp_netdev_event(). From Jiri
Pirko and Timo Teräs.
18) Convert several drivers over to module_pci_driver(), from Peter
Huewe.
19) tcp_fixup_rcvbuf() can loop 500 times over loopback, just use a
O(1) calculation instead. From Eric Dumazet.
20) Support setting of explicit tunnel peer addresses in ipv6, just
like ipv4. From Nicolas Dichtel.
21) Protect x86 BPF JIT against spraying attacks, from Eric Dumazet.
22) Prevent a single high rate flow from overruning an individual cpu
during RX packet processing via selective flow shedding. From
Willem de Bruijn.
23) Don't use spinlocks in TCP md5 signing fast paths, from Eric
Dumazet.
24) Don't just drop GSO packets which are above the TBF scheduler's
burst limit, chop them up so they are in-bounds instead. Also
from Eric Dumazet.
25) VLAN offloads are missed when configured on top of a bridge, fix
from Vlad Yasevich.
26) Support IPV6 in ping sockets. From Lorenzo Colitti.
27) Receive flow steering targets should be updated at poll() time
too, from David Majnemer.
28) Fix several corner case regressions in PMTU/redirect handling due
to the routing cache removal, from Timo Teräs.
29) We have to be mindful of ipv4 mapped ipv6 sockets in
upd_v6_push_pending_frames(). From Hannes Frederic Sowa.
30) Fix L2TP sequence number handling bugs, from James Chapman."
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1214 commits)
drivers/net: caif: fix wrong rtnl_is_locked() usage
drivers/net: enic: release rtnl_lock on error-path
vhost-net: fix use-after-free in vhost_net_flush
net: mv643xx_eth: do not use port number as platform device id
net: sctp: confirm route during forward progress
virtio_net: fix race in RX VQ processing
virtio: support unlocked queue poll
net/cadence/macb: fix bug/typo in extracting gem_irq_read_clear bit
Documentation: Fix references to defunct linux-net@vger.kernel.org
net/fs: change busy poll time accounting
net: rename low latency sockets functions to busy poll
bridge: fix some kernel warning in multicast timer
sfc: Fix memory leak when discarding scattered packets
sit: fix tunnel update via netlink
dt:net:stmmac: Add dt specific phy reset callback support.
dt:net:stmmac: Add support to dwmac version 3.610 and 3.710
dt:net:stmmac: Allocate platform data only if its NULL.
net:stmmac: fix memleak in the open method
ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available
net: ipv6: fix wrong ping_v6_sendmsg return value
...
I was reviewing code which I suspected might allocate a zero size SG
table. That will cause memory corruption. Also we can't return before
doing the memset or we could end up using uninitialized memory in the
cleanup path.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only difference between sg_pcopy_{from,to}_buffer() and
sg_copy_{from,to}_buffer() is an additional argument that specifies the
number of bytes to skip the SG list before copying.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Horia Geanta <horia.geanta@freescale.com>
Cc: Imre Deak <imre.deak@intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset introduces sg_pcopy_from_buffer() and sg_pcopy_to_buffer(),
which copy data between a linear buffer and an SG list.
The only difference between sg_pcopy_{from,to}_buffer() and
sg_copy_{from,to}_buffer() is an additional argument that specifies the
number of bytes to skip the SG list before copying.
The main reason for introducing these functions is to fix a problem in
scsi_debug module. And there is a local function in crypto/talitos
module, which can be replaced by sg_pcopy_to_buffer().
This patch:
sg_miter_get_next_page() is used to proceed page iterator to the next page
if necessary, and will be used to implement the variants of
sg_copy_{from,to}_buffer() later.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Horia Geanta <horia.geanta@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset is for supporting LZ4 compression and the crypto API using
it.
As shown below, the size of data is a little bit bigger but compressing
speed is faster under the enabled unaligned memory access. We can use
lz4 de/compression through crypto API as well. Also, It will be useful
for another potential user of lz4 compression.
lz4 Compression Benchmark:
Compiler: ARM gcc 4.6.4
ARMv7, 1 GHz based board
Kernel: linux 3.4
Uncompressed data Size: 101 MB
Compressed Size compression Speed
LZO 72.1MB 32.1MB/s, 33.0MB/s(UA)
LZ4 75.1MB 30.4MB/s, 35.9MB/s(UA)
LZ4HC 59.8MB 2.4MB/s, 2.5MB/s(UA)
- UA: Unaligned memory Access support
- Latest patch set for LZO applied
This patch:
Add support for LZ4 compression in the Linux Kernel. LZ4 Compression APIs
for kernel are based on LZ4 implementation by Yann Collet and were changed
for kernel coding style.
LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository : http://code.google.com/p/lz4/
svn revision : r90
Two APIs are added:
lz4_compress() support basic lz4 compression whereas lz4hc_compress()
support high compression or CPU performance get lower but compression
ratio get higher. Also, we require the pre-allocated working memory with
the defined size and destination buffer must be allocated with the size of
lz4_compressbound.
[akpm@linux-foundation.org: make lz4_compresshcctx() static]
Signed-off-by: Chanho Min <chanho.min@lge.com>
Cc: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Herbert Xu <herbert@gondor.hengli.com.au>
Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for extracting LZ4-compressed kernel images, as well as
LZ4-compressed ramdisk images in the kernel boot process.
Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for LZ4 decompression in the Linux Kernel. LZ4 Decompression
APIs for kernel are based on LZ4 implementation by Yann Collet.
Benchmark Results(PATCH v3)
Compiler: Linaro ARM gcc 4.6.2
1. ARMv7, 1.5GHz based board
Kernel: linux 3.4
Uncompressed Kernel Size: 14MB
Compressed Size Decompression Speed
LZO 6.7MB 20.1MB/s, 25.2MB/s(UA)
LZ4 7.3MB 29.1MB/s, 45.6MB/s(UA)
2. ARMv7, 1.7GHz based board
Kernel: linux 3.7
Uncompressed Kernel Size: 14MB
Compressed Size Decompression Speed
LZO 6.0MB 34.1MB/s, 52.2MB/s(UA)
LZ4 6.5MB 86.7MB/s
- UA: Unaligned memory Access support
- Latest patch set for LZO applied
This patch set is for adding support for LZ4-compressed Kernel. LZ4 is a
very fast lossless compression algorithm and it also features an extremely
fast decoder [1].
But we have five of decompressors already and one question which does
arise, however, is that of where do we stop adding new ones? This issue
had been discussed and came to the conclusion [2].
Russell King said that we should have:
- one decompressor which is the fastest
- one decompressor for the highest compression ratio
- one popular decompressor (eg conventional gzip)
If we have a replacement one for one of these, then it should do exactly
that: replace it.
The benchmark shows that an 8% increase in image size vs a 66% increase
in decompression speed compared to LZO(which has been known as the
fastest decompressor in the Kernel). Therefore the "fast but may not be
small" compression title has clearly been taken by LZ4 [3].
[1] http://code.google.com/p/lz4/
[2] http://thread.gmane.org/gmane.linux.kbuild.devel/9157
[3] http://thread.gmane.org/gmane.linux.kbuild.devel/9347
LZ4 homepage: http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository: http://code.google.com/p/lz4/
Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: Yann Collet <yann.collet.73@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some architectures need __c[lt]z[sd]i2() for __builtin_c[lt]z[ll] and
that causes a build failure. They can be implemented using the
fls()/__ffs() and overridden by linking arch-specific versions may not
be implemented yet.
This is required by "lib: add lz4 compressor module".
Reference: https://lkml.org/lkml/2013/4/18/603
Signed-off-by: Chanho Min <chanho.min@lge.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Herbert Xu <herbert@gondor.hengli.com.au>
Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull trivial tree updates from Jiri Kosina:
"The usual stuff from trivial tree"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits)
treewide: relase -> release
Documentation/cgroups/memory.txt: fix stat file documentation
sysctl/net.txt: delete reference to obsolete 2.4.x kernel
spinlock_api_smp.h: fix preprocessor comments
treewide: Fix typo in printk
doc: device tree: clarify stuff in usage-model.txt.
open firmware: "/aliasas" -> "/aliases"
md: bcache: Fixed a typo with the word 'arithmetic'
irq/generic-chip: fix a few kernel-doc entries
frv: Convert use of typedef ctl_table to struct ctl_table
sgi: xpc: Convert use of typedef ctl_table to struct ctl_table
doc: clk: Fix incorrect wording
Documentation/arm/IXP4xx fix a typo
Documentation/networking/ieee802154 fix a typo
Documentation/DocBook/media/v4l fix a typo
Documentation/video4linux/si476x.txt fix a typo
Documentation/virtual/kvm/api.txt fix a typo
Documentation/early-userspace/README fix a typo
Documentation/video4linux/soc-camera.txt fix a typo
lguest: fix CONFIG_PAE -> CONFIG_x86_PAE in comment
...
Merge Kconfig menu diet patches from Dave Hansen:
"I think the "Kernel Hacking" menu has gotten a bit out of hand. It is
over 120 lines long on my system with everything enabled and options
are scattered around it haphazardly.
http://sr71.net/~dave/linux/kconfig-horror.png
Let's try to introduce some sanity. This set takes that 120 lines
down to 55 and makes it vastly easier to find some things. It's a
start.
This set stands on its own, but there is plenty of room for follow-up
patches. The arch-specific debug options still end up getting stuck
in the top-level "kernel hacking" menu. OPTIMIZE_INLINING, for
instance, could obviously go in to the "compiler options" menu, but
the fact that it is defined in arch/ in a separate Kconfig file keeps
it on its own for the moment.
The Signed-off-by's in here look funky. I changed employers while
working on this set, so I have signoffs from both email addresses"
* emailed patches from Dave Hansen <dave@sr71.net>:
hang and lockup detection menu
kconfig: consolidate printk options
group locking debugging options
consolidate compilation option configs
consolidate runtime testing configs
order memory debugging Kconfig options
consolidate per-arch stack overflow debugging options
The hard/softlockup and hung-task entries take up 6 lines
of screen real-estate when enabled. I bet folks don't
mess with these _that_ often, so move them in a group
down a level.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Same deal, take the printk-related things and hide them in a menu.
This takes another 4 items out of the top-level menu.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original posting:
http://lkml.kernel.org/r/20121214184208.D9E5804D@kernel.stglabs.ibm.com
There are quite a few of these, and we want to make sure that
there is one-stop-shopping for lock debugging.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original Post:
http://lkml.kernel.org/r/20121214184207.6E00DDEC@kernel.stglabs.ibm.com
Again, trying to come up with some common themes of the stuff in
the kernel hacking menu... There are quite a few options to
tweak compilation in some way, or perform extra compile-time
checks. Give them their own menu.
The diff here looks a bit funny... makes it look like I'm
moving debugfs even though I'm actually moving the options on
either side of it.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original posting:
http://lkml.kernel.org/r/20121214184206.FC11422F@kernel.stglabs.ibm.com
These runtime tests are great, except that there are a lot of them,
and they are very rarely needed. Give them their own menu so that
only the folks who need them will have to go looking for them.
Note that there are some other runtime tests that are not in here,
like for RCU or locking. This menu should only be used for tests
that do not have a more appropriate home.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original posting:
http://lkml.kernel.org/r/20121214184203.37E6C724@kernel.stglabs.ibm.com
There are a *LOT* of memory debugging options. They are just scattered
all over the "Kernel Hacking" menu. Sure, "memory debugging" is a very
vague term and it's going to be hard to make absolute rules about what
goes in here, but this has to be better than what we had before.
This does, however, leave out the architecture-specific memory
debugging options (like x86's DEBUG_SET_MODULE_RONX). There would need
to be some substantial changes to move those in here. Kconfig can not
easily mix arch-specific and generic options together: it really
requires a file per-architecture, and I think having an
arch/foo/Kconfig.debug-memory might be taking things a bit too far
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Original posting:
http://lkml.kernel.org/r/20121214184202.F54094D9@kernel.stglabs.ibm.com
Several architectures have similar stack debugging config options.
They all pretty much do the same thing, some with slightly
differing help text.
This patch changes the architectures to instead enable a Kconfig
boolean, and then use that boolean in the generic Kconfig.debug
to present the actual menu option. This removes a bunch of
duplication and adds consistency across arches.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Reviewed-by: H. Peter Anvin <hpa@zytor.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com> [for tile]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge first patch-bomb from Andrew Morton:
- various misc bits
- I'm been patchmonkeying ocfs2 for a while, as Joel and Mark have been
distracted. There has been quite a bit of activity.
- About half the MM queue
- Some backlight bits
- Various lib/ updates
- checkpatch updates
- zillions more little rtc patches
- ptrace
- signals
- exec
- procfs
- rapidio
- nbd
- aoe
- pps
- memstick
- tools/testing/selftests updates
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (445 commits)
tools/testing/selftests: don't assume the x bit is set on scripts
selftests: add .gitignore for kcmp
selftests: fix clean target in kcmp Makefile
selftests: add .gitignore for vm
selftests: add hugetlbfstest
self-test: fix make clean
selftests: exit 1 on failure
kernel/resource.c: remove the unneeded assignment in function __find_resource
aio: fix wrong comment in aio_complete()
drivers/w1/slaves/w1_ds2408.c: add magic sequence to disable P0 test mode
drivers/memstick/host/r592.c: convert to module_pci_driver
drivers/memstick/host/jmb38x_ms: convert to module_pci_driver
pps-gpio: add device-tree binding and support
drivers/pps/clients/pps-gpio.c: convert to module_platform_driver
drivers/pps/clients/pps-gpio.c: convert to devm_* helpers
drivers/parport/share.c: use kzalloc
Documentation/accounting/getdelays.c: avoid strncpy in accounting tool
aoe: update internal version number to v83
aoe: update copyright date
aoe: perform I/O completions in parallel
...
We print a dump stack after idr_remove warning. This is useful to find
the faulty piece of code. Let's do the same for ida_remove, as it would
be equally useful there.
[akpm@linux-foundation.org: convert the open-coded printk+dump_stack into WARN()]
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__this_cpu_write doesn't need to be protected by spinlock, AS we are doing
per cpu write with preempt disabled. And another reason to remove
__this_cpu_write outside of spinlock: __percpu_counter_sum is not an
accurate counter.
Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add functionality to serialize the output from dump_stack() to avoid
mangling of the output when dump_stack is called simultaneously from
multiple cpus.
[akpm@linux-foundation.org: fix comment indenting, avoid inclusion of <asm/> files - use <linux/> where possiblem fix uniprocessor build (__dump_stack undefined), remove unneeded ifdef around smp.h inclusion]
Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Reported-by: Russ Anderson <rja@sgi.com>
Reviewed-by: Robin Holt <holt@sgi.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull "exotic" arch fixes from Geert Uytterhoeven:
"This is a collection of several exotic architecture fixes, and a few
other fixes for issues that were detected while doing the former"
* 'exotic-arch-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k: (35 commits)
lib: Move fonts from drivers/video/console/ to lib/fonts/
console/font: Refactor font support code selection logic
Revert "staging/solo6x10: depend on CONFIG_FONTS"
input: cros_ec_keyb_clear_keyboard() depends on CONFIG_PM_SLEEP
score: Wire up asm-generic/xor.h
score: Remove unneeded <asm/dma-mapping.h>
openrisc: Wire up asm-generic/xor.h
h8300/boot: Use POSIX "$((..))" instead of bashism "$[...]"
h8300: Mark H83002 and H83048 CPU support broken
h8300: Switch h8300 to drivers/Kconfig
h8300: Limit timer channel ranges in Kconfig
h8300: Wire up asm-generic/xor.h
h8300: Fill the system call table using a CALL() macro
h8300: Fix <asm/tlb.h>
h8300: Hardcode symbol prefixes in asm sources
h8300: add missing definition for read_barries_depends()
frv: head.S - Remove commented-out initialization code
cris: Wire up asm-generic/vga.h
parport: disable PC-style parallel port support on cris
console: Disable VGA text console support on cris
...
Pull per-cpu changes from Tejun Heo:
"This pull request contains Kent's per-cpu reference counter. It has
gone through several iterations since the last time and the dynamic
allocation is gone.
The usual usage is relatively straight-forward although async kill
confirm interface, which is not used int most cases, is somewhat icky.
There also are some interface concerns - e.g. I'm not sure about
passing in @relesae callback during init as that becomes funny when we
later implement synchronous kill_and_drain - but nothing too serious
and it's quite useable now.
cgroup_subsys_state refcnting has already been converted and we should
convert module refcnt (Kent?)"
* 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu-refcount: use RCU-sched insted of normal RCU
percpu-refcount: implement percpu_tryget() along with percpu_ref_kill_and_confirm()
percpu-refcount: implement percpu_ref_cancel_init()
percpu-refcount: add __must_check to percpu_ref_init() and don't use ACCESS_ONCE() in percpu_ref_kill_rcu()
percpu-refcount: cosmetic updates
percpu-refcount: consistently use plain (non-sched) RCU
percpu-refcount: Don't use silly cmpxchg()
percpu: implement generic percpu refcounting
Pull WW mutex support from Ingo Molnar:
"This tree adds support for wound/wait style locks, which the graphics
guys would like to make use of in the TTM graphics subsystem.
Wound/wait mutexes are used when other multiple lock acquisitions of a
similar type can be done in an arbitrary order. The deadlock handling
used here is called wait/wound in the RDBMS literature: The older
tasks waits until it can acquire the contended lock. The younger
tasks needs to back off and drop all the locks it is currently
holding, ie the younger task is wounded.
See this LWN.net description of W/W mutexes:
https://lwn.net/Articles/548909/
The comments there outline specific usecases for this facility (which
have already been implemented for the DRM tree).
Also see Documentation/ww-mutex-design.txt for more details"
* 'core-mutexes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking-selftests: Handle unexpected failures more strictly
mutex: Add more w/w tests to test EDEADLK path handling
mutex: Add more tests to lib/locking-selftest.c
mutex: Add w/w tests to lib/locking-selftest.c
mutex: Add w/w mutex slowpath debugging
mutex: Add support for wound/wait style locks
arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
These are various bug fixes that were not considered important enough
for merging into 3.10. The majority of the ARM fixes are for the OMAP
and at91 platforms, and there is another set of bug fixes for device
drivers that resolve 'randconfig' build errors and that the subsystem
maintainers either did not pick up or preferred to get merged through
the arm-soc tree.
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Merge tag 'fixes-non-critical-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC non-cricitical bug fixes from Arnd Bergmann:
"These are various bug fixes that were not considered important enough
for merging into 3.10.
The majority of the ARM fixes are for the OMAP and at91 platforms, and
there is another set of bug fixes for device drivers that resolve
'randconfig' build errors and that the subsystem maintainers either
did not pick up or preferred to get merged through the arm-soc tree."
* tag 'fixes-non-critical-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (43 commits)
ARM: at91/PMC: use at91_usb_rate() for UTMI PLL
ARM: at91/PMC: fix at91sam9n12 USB FS init
ARM: at91/PMC: at91sam9n12 family has a PLLB
ARM: at91/PMC: sama5d3 family doesn't have a PLLB
ARM: tegra: fix section mismatch in tegra_pmc_parse_dt
ARM: mxs: don't select HAVE_PWM
ARM: mxs: stub out mxs_pm_init for !CONFIG_PM
cpuidle: calxeda: select ARM_CPU_SUSPEND
ARM: mvebu: fix length of ethernet registers in mv78260 dtsi
ARM: at91: cpuidle: Fix target_residency
ARM: at91: fix at91_extern_irq usage for non-dt boards
ARM: sirf: use CONFIG_SIRF rather than CONFIG_PRIMA2 where necessary
clocksource: kona: adapt to CLOCKSOURCE_OF_DECLARE change
X.509: do not emit any informational output
mtd: omap2: allow bulding as a module
[SCSI] nsp32: use mdelay instead of large udelay constants
hwrng: bcm2835: fix MODULE_LICENSE tag
ARM: at91: Change the internal SRAM memory type MT_MEMORY_NONCACHED
ARM: at91: Fix link breakage when !CONFIG_PHYLIB
MAINTAINERS: Add exynos filename match to ARM/S5P EXYNOS ARM ARCHITECTURES
...
Here's the big driver core merge for 3.11-rc1
Lots of little things, and larger firmware subsystem updates, all
described in the shortlog. Nice thing here is that we finally get rid
of CONFIG_HOTPLUG, after 10+ years, thanks to Stephen Rohtwell (it had
been always on for a number of kernel releases, now it's just removed.)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-3.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here's the big driver core merge for 3.11-rc1
Lots of little things, and larger firmware subsystem updates, all
described in the shortlog. Nice thing here is that we finally get rid
of CONFIG_HOTPLUG, after 10+ years, thanks to Stephen Rohtwell (it had
been always on for a number of kernel releases, now it's just
removed)"
* tag 'driver-core-3.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (27 commits)
driver core: device.h: fix doc compilation warnings
firmware loader: fix another compile warning with PM_SLEEP unset
build some drivers only when compile-testing
firmware loader: fix compile warning with PM_SLEEP set
kobject: sanitize argument for format string
sysfs_notify is only possible on file attributes
firmware loader: simplify holding module for request_firmware
firmware loader: don't export cache_firmware and uncache_firmware
drivers/base: Use attribute groups to create sysfs memory files
firmware loader: fix compile warning
firmware loader: fix build failure with !CONFIG_FW_LOADER_USER_HELPER
Documentation: Updated broken link in HOWTO
Finally eradicate CONFIG_HOTPLUG
driver core: firmware loader: kill FW_ACTION_NOHOTPLUG requests before suspend
driver core: firmware loader: don't cache FW_ACTION_NOHOTPLUG firmware
Documentation: Tidy up some drivers/base/core.c kerneldoc content.
platform_device: use a macro instead of platform_driver_register
firmware: move EXPORT_SYMBOL annotations
firmware: Avoid deadlock of usermodehelper lock at shutdown
dell_rbu: Select CONFIG_FW_LOADER_USER_HELPER explicitly
...
In order to avoid making code that deals with printing both, IPv4 and
IPv6 addresses, unnecessary complicated as for example ...
if (sa.sa_family == AF_INET6)
printk("... %pI6 ...", ..sin6_addr);
else
printk("... %pI4 ...", ..sin_addr.s_addr);
... it would be better to introduce a format specifier that can deal
with those kind of situations internally; just as we have a "struct
sockaddr" for generic mapping into "struct sockaddr_in" or "struct
sockaddr_in6" as e.g. done in "union sctp_addr". Then, we could
reduce the above statement into something like:
printk("... %pIS ..", &sockaddr);
In case our pointer is NULL, pointer() then deals with that already at
an earlier point in time internally. While we're at it, support for both
%piS/%pIS, where 'S' stands for sockaddr, comes (almost) for free.
Additionally to that, postfix specifiers 'p', 'f' and 's' are supported
as suggested and initially implemented in 2009 by Joe Perches [1].
Handling of those additional specifiers orientate on the initial RFC that
was proposed. Also we support IPv6 compressed format specified by 'c' and
various other IPv4 extensions as stated in the documentation part.
Likely, there are many other areas than just SCTP in the kernel to make
use of this extension as well.
[1] http://patchwork.ozlabs.org/patch/31480/
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
CC: Joe Perches <joe@perches.com>
CC: linux-kernel@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
Several drivers need font support independent of CONFIG_VT, cfr. commit
9cbce8d7e1dae0744ca4f68d62aa7de18196b6f4, "console/font: Refactor font
support code selection logic").
Hence move the fonts and their support logic from drivers/video/console/ to
its own library directory lib/fonts/.
This also allows to limit processing of drivers/video/console/Makefile to
CONFIG_VT=y again.
[Kevin Hilman <khilman@linaro.org>: Update arch/arm/boot/compressed/Makefile]
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
When CONFIG_PROVE_LOCKING is not enabled, more tests are
expected to pass unexpectedly, but there no tests that should
start to fail that pass with CONFIG_PROVE_LOCKING enabled.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: rostedt@goodmis.org
Cc: daniel@ffwll.ch
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20130620113151.4001.77963.stgit@patser
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Injects EDEADLK conditions at pseudo-random interval, with
exponential backoff up to UINT_MAX (to ensure that every lock
operation still completes in a reasonable time).
This way we can test the wound slowpath even for ww mutex users
where contention is never expected, and the ww deadlock
avoidance algorithm is only needed for correctness against
malicious userspace. An example would be protecting kernel
modesetting properties, which thanks to single-threaded X isn't
really expected to contend, ever.
I've looked into using the CONFIG_FAULT_INJECTION
infrastructure, but decided against it for two reasons:
- EDEADLK handling is mandatory for ww mutex users and should
never affect the outcome of a syscall. This is in contrast to -ENOMEM
injection. So fine configurability isn't required.
- The fault injection framework only allows to set a simple
probability for failure. Now the probability that a ww mutex acquire
stage with N locks will never complete (due to too many injected
EDEADLK backoffs) is zero. But the expected number of ww_mutex_lock
operations for the completely uncontended case would be O(exp(N)).
The per-acuiqire ctx exponential backoff solution choosen here only
results in O(log N) overhead due to injection and so O(log N * N)
lock operations. This way we can fail with high probability (and so
have good test coverage even for fancy backoff and lock acquisition
paths) without running into patalogical cases.
Note that EDEADLK will only ever be injected when we managed to
acquire the lock. This prevents any behaviour changes for users
which rely on the EALREADY semantics.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: rostedt@goodmis.org
Cc: daniel@ffwll.ch
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20130620113117.4001.21681.stgit@patser
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Wound/wait mutexes are used when other multiple lock
acquisitions of a similar type can be done in an arbitrary
order. The deadlock handling used here is called wait/wound in
the RDBMS literature: The older tasks waits until it can acquire
the contended lock. The younger tasks needs to back off and drop
all the locks it is currently holding, i.e. the younger task is
wounded.
For full documentation please read Documentation/ww-mutex-design.txt.
References: https://lwn.net/Articles/548909/
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Rob Clark <robdclark@gmail.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: rostedt@goodmis.org
Cc: daniel@ffwll.ch
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/51C8038C.9000106@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
FAULT_INJECTION_STACKTRACE_FILTER selects FRAME_POINTER but
that symbol is not available for MIPS.
Fixes the following problem on a randconfig:
warning: (LOCKDEP && FAULT_INJECTION_STACKTRACE_FILTER && LATENCYTOP &&
KMEMCHECK) selects FRAME_POINTER which has unmet direct dependencies
(DEBUG_KERNEL && (CRIS || M68K || FRV || UML || AVR32 || SUPERH || BLACKFIN ||
MN10300 || METAG) || ARCH_WANT_FRAME_POINTERS)
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5441/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
When building a kernel using 'make -s', I expect to see an empty output,
except for build warnings and errors. The build_OID_registry code
always prints one line when run, which is not helpful to most people
building the kernels, and which makes it harder to automatically
check for build warnings.
Let's just remove the one line output.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Correct spelling typo in printk within various drivers.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
percpu-refcount was incorrectly using preempt_disable/enable() for RCU
critical sections against call_rcu(). 6a24474da8 ("percpu-refcount:
consistently use plain (non-sched) RCU") fixed it by converting the
preepmtion operations with rcu_read_[un]lock() citing that there isn't
any advantage in using sched-RCU over using the usual one; however,
rcu_read_[un]lock() for the preemptible RCU implementation -
CONFIG_TREE_PREEMPT_RCU, chosen when CONFIG_PREEMPT - are slightly
more expensive than preempt_disable/enable().
In a contrived microbench which repeats the followings,
- percpu_ref_get()
- copy 32 bytes of data into percpu buffer
- percpu_put_get()
- copy 32 bytes of data into percpu buffer
rcu_read_[un]lock() used in percpu_ref_get/put() makes it go slower by
about 15% when compared to using sched-RCU.
As the RCU critical sections are extremely short, using sched-RCU
shouldn't have any latency implications. Convert to RCU-sched.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Kent Overstreet <koverstreet@google.com>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Implement percpu_tryget() which stops giving out references once the
percpu_ref is visible as killed. Because the refcnt is per-cpu,
different CPUs will start to see a refcnt as killed at different
points in time and tryget() may continue to succeed on subset of cpus
for a while after percpu_ref_kill() returns.
For use cases where it's necessary to know when all CPUs start to see
the refcnt as dead, percpu_ref_kill_and_confirm() is added. The new
function takes an extra argument @confirm_kill which is invoked when
the refcnt is guaranteed to be viewed as killed on all CPUs.
While this isn't the prettiest interface, it doesn't force synchronous
wait and is much safer than requiring the caller to do its own
call_rcu().
v2: Patch description rephrased to emphasize that tryget() may
continue to succeed on some CPUs after kill() returns as suggested
by Kent.
v3: Function comment in percpu_ref_kill_and_confirm() updated warning
people to not depend on the implied RCU grace period from the
confirm callback as it's an implementation detail.
Signed-off-by: Tejun Heo <tj@kernel.org>
Slightly-Grumpily-Acked-by: Kent Overstreet <koverstreet@google.com>
Normally, percpu_ref_init() initializes and percpu_ref_kill()
initiates destruction which completes asynchronously. The
asynchronous destruction can be problematic in init failure path where
the caller wants to destroy half-constructed object - distinguishing
half-constructed objects from the usual release method can be painful
for complex objects.
This patch implements percpu_ref_cancel_init() which synchronously
destroys the percpu_ref without invoking release. To avoid
unintentional misuses, the function requires the ref to have finished
percpu_ref_init() but never used and triggers WARN otherwise.
v2: Explain the weird name and usage restriction in the function
comment.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Kent Overstreet <koverstreet@google.com>
Russell King
