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authorVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>2006-12-07 02:14:13 +0100
committerAndi Kleen <andi@basil.nowhere.org>2006-12-07 02:14:13 +0100
commitd331e739f5ad2aaa9d8553891ba6ca823bdbce37 (patch)
tree5da7042a022dd119c9b920ceb4101e7203bccb44 /arch/x86_64
parenta0429d0d7a6116dedcb71d9128da904bf135f189 (diff)
downloadlinux-linaro-stable-d331e739f5ad2aaa9d8553891ba6ca823bdbce37.tar.gz
[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>
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/kernel/process.c19
1 files changed, 17 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 *)&current_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)