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| author | Andi Kleen <ak@suse.de> | 2006-11-14 16:57:46 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-11-14 16:57:46 +0100 |
| commit | 9446868b5383eb87f76b2d4389dea4bb968a6657 (patch) | |
| tree | d253d9a0ae99c77f43ca271019fcbdbfd349b665 /include/asm-x86_64/pda.h | |
| parent | [PATCH] x86-64: Fix vgetcpu when CONFIG_HOTPLUG_CPU is disabled (diff) | |
| download | linux-9446868b5383eb87f76b2d4389dea4bb968a6657.tar.xz linux-9446868b5383eb87f76b2d4389dea4bb968a6657.zip | |
[PATCH] x86-64: Fix race in exit_idle
When another interrupt happens in exit_idle the exit idle notifier
could be called an incorrect number of times.
Add a test_and_clear_bit_pda and use it handle the bit
atomically against interrupts to avoid this.
Pointed out by Stephane Eranian
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'include/asm-x86_64/pda.h')
| -rw-r--r-- | include/asm-x86_64/pda.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/asm-x86_64/pda.h b/include/asm-x86_64/pda.h index 14996d962bac..5642634843c4 100644 --- a/include/asm-x86_64/pda.h +++ b/include/asm-x86_64/pda.h @@ -109,6 +109,15 @@ extern struct x8664_pda _proxy_pda; #define sub_pda(field,val) pda_to_op("sub",field,val) #define or_pda(field,val) pda_to_op("or",field,val) +/* This is not atomic against other CPUs -- CPU preemption needs to be off */ +#define test_and_clear_bit_pda(bit,field) ({ \ + int old__; \ + asm volatile("btr %2,%%gs:%c3\n\tsbbl %0,%0" \ + : "=r" (old__), "+m" (_proxy_pda.field) \ + : "dIr" (bit), "i" (pda_offset(field)) : "memory"); \ + old__; \ +}) + #endif #define PDA_STACKOFFSET (5*8) |