linux-sg2042/include
Oleg Nesterov a8d4b8345e introduce __fcheck_files() to fix rcu_dereference_check_fdtable(), kill rcu_my_thread_group_empty()
rcu_dereference_check_fdtable() looks very wrong,

1. rcu_my_thread_group_empty() was added by 844b9a8707 "vfs: fix
   RCU-lockdep false positive due to /proc" but it doesn't really
   fix the problem. A CLONE_THREAD (without CLONE_FILES) task can
   hit the same race with get_files_struct().

   And otoh rcu_my_thread_group_empty() can suppress the correct
   warning if the caller is the CLONE_FILES (without CLONE_THREAD)
   task.

2. files->count == 1 check is not really right too. Even if this
   files_struct is not shared it is not safe to access it lockless
   unless the caller is the owner.

   Otoh, this check is sub-optimal. files->count == 0 always means
   it is safe to use it lockless even if files != current->files,
   but put_files_struct() has to take rcu_read_lock(). See the next
   patch.

This patch removes the buggy checks and turns fcheck_files() into
__fcheck_files() which uses rcu_dereference_raw(), the "unshared"
callers, fget_light() and fget_raw_light(), can use it to avoid
the warning from RCU-lockdep.

fcheck_files() is trivially reimplemented as rcu_lockdep_assert()
plus __fcheck_files().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-25 03:14:36 -05:00
..
acpi Merge branches 'acpi-pci-pm' and 'acpi-pci-hotplug' 2013-12-31 22:03:37 +01:00
asm-generic mm: Fix NULL pointer dereference in madvise(MADV_WILLNEED) support 2013-12-20 12:17:03 -08:00
clocksource
crypto crypto: scatterwalk - Use sg_chain_ptr on chain entries 2013-12-09 19:58:52 +08:00
drm drm/radeon: 0x9649 is SUMO2 not SUMO 2013-12-23 10:03:41 -05:00
dt-bindings For the 3.13 merge window we have a couple of new drivers for the AMS 2013-11-15 16:37:40 -08:00
keys
kvm
linux introduce __fcheck_files() to fix rcu_dereference_check_fdtable(), kill rcu_my_thread_group_empty() 2014-01-25 03:14:36 -05:00
math-emu
media [media] videobuf2: Add support for file access mode flags for DMABUF exporting 2013-12-09 14:50:50 -02:00
memory
misc
net ipv6: simplify detection of first operational link-local address on interface 2014-01-17 18:10:01 -08:00
pcmcia
ras
rdma IB/core: const'ify inbuf in struct ib_udata 2013-12-16 10:38:28 -08:00
rxrpc
scsi [SCSI] Disable WRITE SAME for RAID and virtual host adapter drivers 2013-11-29 08:48:39 +04:00
sound ALSA: memalloc.h - fix wrong truncation of dma_addr_t 2013-12-10 15:30:46 +01:00
target target/file: Update hw_max_sectors based on current block_size 2013-12-19 00:18:54 -08:00
trace Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-12-02 10:13:09 -08:00
uapi Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux 2014-01-01 11:36:16 -08:00
video fbdev changes for 3.13 2013-11-14 14:44:20 +09:00
xen Bug-fixes: 2013-12-20 09:34:54 -08:00
Kbuild