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| author | Borislav Petkov <bp@alien8.de> | 2016-03-09 21:56:22 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-03-10 11:27:12 +0100 |
| commit | 84477336ec03f8061ffd6908da341e063e5d6d1f (patch) | |
| tree | c5b17f64a9fd0f611810039705d0cbe5741ca6de | |
| parent | a65050c6f17e52442716138d48d0a47301a8344b (diff) | |
| download | lwn-84477336ec03f8061ffd6908da341e063e5d6d1f.tar.gz lwn-84477336ec03f8061ffd6908da341e063e5d6d1f.zip | |
x86/delay: Avoid preemptible context checks in delay_mwaitx()
We do use this_cpu_ptr(&cpu_tss) as a cacheline-aligned, seldomly
accessed per-cpu var as the MONITORX target in delay_mwaitx(). However,
when called in preemptible context, this_cpu_ptr -> smp_processor_id() ->
debug_smp_processor_id() fires:
BUG: using smp_processor_id() in preemptible [00000000] code: udevd/312
caller is delay_mwaitx+0x40/0xa0
But we don't care about that check - we only need cpu_tss as a MONITORX
target and it doesn't really matter which CPU's var we're touching as
we're going idle anyway. Fix that.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: spg_linux_kernel@amd.com
Link: http://lkml.kernel.org/r/20160309205622.GG6564@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/lib/delay.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c index e912b2f6d36e..2f07c291dcc8 100644 --- a/arch/x86/lib/delay.c +++ b/arch/x86/lib/delay.c @@ -102,7 +102,7 @@ static void delay_mwaitx(unsigned long __loops) * Use cpu_tss as a cacheline-aligned, seldomly * accessed per-cpu variable as the monitor target. */ - __monitorx(this_cpu_ptr(&cpu_tss), 0, 0); + __monitorx(raw_cpu_ptr(&cpu_tss), 0, 0); /* * AMD, like Intel, supports the EAX hint and EAX=0xf |