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Filename Latest commit message Latest commit date
Tejun Heo b3a5d11199 percpu_ref: Update doc to dissuade users from depending on internal RCU grace periods
percpu_ref internally uses sched-RCU to implement the percpu -> atomic
mode switching and the documentation suggested that this could be
depended upon.  This doesn't seem like a good idea.

* percpu_ref uses sched-RCU which has different grace periods regular
  RCU.  Users may combine percpu_ref with regular RCU usage and
  incorrectly believe that regular RCU grace periods are performed by
  percpu_ref.  This can lead to, for example, use-after-free due to
  premature freeing.

* percpu_ref has a grace period when switching from percpu to atomic
  mode.  It doesn't have one between the last put and release.  This
  distinction is subtle and can lead to surprising bugs.

* percpu_ref allows starting in and switching to atomic mode manually
  for debugging and other purposes.  This means that there may not be
  any grace periods from kill to release.

This patch makes it clear that the grace periods are percpu_ref's
internal implementation detail and can't be depended upon by the
users.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2018-03-19 10:09:44 -07:00
..
acpi ACPICA: Update version to 20180105 2018-02-06 10:32:13 +01:00
asm-generic RISC-V changes for 4.16 2018-02-07 11:33:08 -08:00
clocksource
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
drm drm/graphics pull request for v4.16-rc1 2018-02-01 17:48:47 -08:00
dt-bindings MIPS changes for 4.16 2018-02-07 11:22:44 -08:00
keys
kvm KVM changes for 4.16 2018-02-10 13:16:35 -08:00
linux percpu_ref: Update doc to dissuade users from depending on internal RCU grace periods 2018-03-19 10:09:44 -07:00
math-emu
media vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
memory
misc powerpc updates for 4.16 2018-02-02 10:01:04 -08:00
net vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pcmcia
ras
rdma IB/core: Map iWarp AH type to undefined in rdma_ah_find_type 2018-02-01 15:43:31 -07:00
scsi SCSI postmerge on 20180202 2018-02-03 13:07:56 -08:00
soc ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
sound ASoC: Updates for v4.16 2018-02-07 12:11:09 -08:00
target target core: add device action configfs files 2018-01-16 18:05:04 -08:00
trace Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
uapi unify {de,}mangle_poll(), get rid of kernel-side POLL... 2018-02-11 14:37:22 -08:00
video fbdev changes for v4.16: 2018-02-07 13:10:43 -08:00
xen