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| author | Daniel Thompson <daniel.thompson@linaro.org> | 2015-03-26 20:23:26 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-27 08:34:00 +0100 |
| commit | 1809bfa44e1019e397fabaa6f2349bb7237e57a4 (patch) | |
| tree | 3d2eba58ee4389f00e87b752599c9703f34b7150 /kernel/taskstats.c | |
| parent | timers, sched/clock: Remove redundant notrace from update function (diff) | |
| download | linux-1809bfa44e1019e397fabaa6f2349bb7237e57a4.tar.xz linux-1809bfa44e1019e397fabaa6f2349bb7237e57a4.zip | |
timers, sched/clock: Avoid deadlock during read from NMI
Currently it is possible for an NMI (or FIQ on ARM) to come in
and read sched_clock() whilst update_sched_clock() has locked
the seqcount for writing. This results in the NMI handler
locking up when it calls raw_read_seqcount_begin().
This patch fixes the NMI safety issues by providing banked clock
data. This is a similar approach to the one used in Thomas
Gleixner's 4396e058c52e("timekeeping: Provide fast and NMI safe
access to CLOCK_MONOTONIC").
Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1427397806-20889-6-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/taskstats.c')
0 files changed, 0 insertions, 0 deletions