diff options
| author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2006-12-07 02:14:13 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:13 +0100 |
| commit | d331e739f5ad2aaa9d8553891ba6ca823bdbce37 (patch) | |
| tree | 5da7042a022dd119c9b920ceb4101e7203bccb44 | |
| parent | a0429d0d7a6116dedcb71d9128da904bf135f189 (diff) | |
[PATCH] x86-64: Fix interrupt race in idle callback (3rd try)
Idle callbacks has some races when enter_idle() sets isidle and subsequent
interrupts that can happen on that CPU, before CPU goes to idle. Due to this,
an IDLE_END can get called before IDLE_START. To avoid these races, disable
interrupts before enter_idle and make sure that all idle routines do not
enable interrupts before entering idle.
Note that poll_idle() still has a this race as it has to enable interrupts
before going to idle. But, all other idle routines have the race fixed.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
| -rw-r--r-- | arch/x86_64/kernel/process.c | 19 | ||||
| -rw-r--r-- | include/asm-x86_64/processor.h | 8 |
2 files changed, 25 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index 0b7b4caa4f74..a418ee4c8c62 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -127,6 +127,7 @@ static void default_idle(void) */ static void poll_idle (void) { + local_irq_enable(); cpu_relax(); } @@ -208,6 +209,12 @@ void cpu_idle (void) idle = default_idle; if (cpu_is_offline(smp_processor_id())) play_dead(); + /* + * Idle routines should keep interrupts disabled + * from here on, until they go to idle. + * Otherwise, idle callbacks can misfire. + */ + local_irq_disable(); enter_idle(); idle(); /* In many cases the interrupt that ended idle @@ -245,8 +252,16 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx) /* Default MONITOR/MWAIT with no hints, used for default C1 state */ static void mwait_idle(void) { - local_irq_enable(); - mwait_idle_with_hints(0,0); + if (!need_resched()) { + __monitor((void *)¤t_thread_info()->flags, 0, 0); + smp_mb(); + if (!need_resched()) + __sti_mwait(0, 0); + else + local_irq_enable(); + } else { + local_irq_enable(); + } } void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h index cef17e0f828c..76552d72804c 100644 --- a/include/asm-x86_64/processor.h +++ b/include/asm-x86_64/processor.h @@ -475,6 +475,14 @@ static inline void __mwait(unsigned long eax, unsigned long ecx) : :"a" (eax), "c" (ecx)); } +static inline void __sti_mwait(unsigned long eax, unsigned long ecx) +{ + /* "mwait %eax,%ecx;" */ + asm volatile( + "sti; .byte 0x0f,0x01,0xc9;" + : :"a" (eax), "c" (ecx)); +} + extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx); #define stack_current() \ |