[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>

1 files changed, 8 insertions, 0 deletions

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() \