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authorAndrew Morton <akpm@linux-foundation.org>2007-11-14 17:00:41 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 18:45:44 -0800
commit35d5d08a085c56f153458c3f5d8ce24123617faf (patch)
tree2db6e598e87809bc1ce7838861b2cff18e5fe60d /arch/x86/lib/delay_32.c
parent7eea436433b7b18045f272562e256976f593f7c0 (diff)
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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 <ak@suse.de> Cc: Marin Mitov <mitov@issp.bas.bg> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/lib/delay_32.c')
-rw-r--r--arch/x86/lib/delay_32.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/lib/delay_32.c b/arch/x86/lib/delay_32.c
index 952e7a89c2a..aad9d95469d 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();
}
/*