Commit-ID: 84477336ec03f8061ffd6908da341e063e5d6d1f Gitweb: http://git.kernel.org/tip/84477336ec03f8061ffd6908da341e063e5d6d1f Author: Borislav Petkov <[email protected]> AuthorDate: Wed, 9 Mar 2016 21:56:22 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 10 Mar 2016 11:27:12 +0100
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 <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Huang Rui <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/lib/delay.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c index e912b2f..2f07c29 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
