Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=35d5d08a085c56f153458c3f5d8ce24123617faf Commit: 35d5d08a085c56f153458c3f5d8ce24123617faf Parent: 7eea436433b7b18045f272562e256976f593f7c0 Author: Andrew Morton <[EMAIL PROTECTED]> AuthorDate: Wed Nov 14 17:00:41 2007 -0800 Committer: Linus Torvalds <[EMAIL PROTECTED]> CommitDate: Wed Nov 14 18:45:44 2007 -0800
x86: disable preemption in delay_tsc() Marin Mitov points out that delay_tsc() can misbehave if it is preempted and rescheduled on a different CPU which has a skewed TSC. Fix it by disabling preemption. (I assume that the worst-case behaviour here is a stall of 2^32 cycles) Cc: Andi Kleen <[EMAIL PROTECTED]> Cc: Marin Mitov <[EMAIL PROTECTED]> Cc: Thomas Gleixner <[EMAIL PROTECTED]> Cc: Ingo Molnar <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> --- arch/x86/lib/delay_32.c | 3 +++ arch/x86/lib/delay_64.c | 11 +++++++---- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/x86/lib/delay_32.c b/arch/x86/lib/delay_32.c index 952e7a8..aad9d95 100644 --- a/arch/x86/lib/delay_32.c +++ b/arch/x86/lib/delay_32.c @@ -12,6 +12,7 @@ #include <linux/module.h> #include <linux/sched.h> +#include <linux/preempt.h> #include <linux/delay.h> #include <asm/processor.h> @@ -42,11 +43,13 @@ static void delay_tsc(unsigned long loops) { unsigned long bclock, now; + preempt_disable(); /* TSC's are per-cpu */ rdtscl(bclock); do { rep_nop(); rdtscl(now); } while ((now-bclock) < loops); + preempt_enable(); } /* diff --git a/arch/x86/lib/delay_64.c b/arch/x86/lib/delay_64.c index 0ebbfb9..45cdd3f 100644 --- a/arch/x86/lib/delay_64.c +++ b/arch/x86/lib/delay_64.c @@ -10,7 +10,9 @@ #include <linux/module.h> #include <linux/sched.h> +#include <linux/preempt.h> #include <linux/delay.h> + #include <asm/delay.h> #include <asm/msr.h> @@ -27,14 +29,15 @@ int read_current_timer(unsigned long *timer_value) void __delay(unsigned long loops) { unsigned bclock, now; - + + preempt_disable(); /* TSC's are pre-cpu */ rdtscl(bclock); - do - { + do { rep_nop(); rdtscl(now); } - while((now-bclock) < loops); + while ((now-bclock) < loops); + preempt_enable(); } EXPORT_SYMBOL(__delay); - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html