[PATCH] Fix TIF_POLLING_NRFLAG in ACPI idle routines
Commit 64c7c8f88559624abdbe12b5da6502e8879f8d28 broke the ACPI C2 and C3
sleep states, because it left TIF_POLLING_NRFLAG active even though
those states do not actually poll the reschedule flag at all. As a
result, the CPU wouldn't get sent an IPI when it was to be woken up, and
would only notice that it had runnable processes on the next timer tick.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 83fd1b6..acd875e 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -169,15 +169,11 @@
static void acpi_safe_halt(void)
{
- int polling = test_thread_flag(TIF_POLLING_NRFLAG);
- if (polling) {
- clear_thread_flag(TIF_POLLING_NRFLAG);
- smp_mb__after_clear_bit();
- }
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
if (!need_resched())
safe_halt();
- if (polling)
- set_thread_flag(TIF_POLLING_NRFLAG);
+ set_thread_flag(TIF_POLLING_NRFLAG);
}
static atomic_t c3_cpu_count;
@@ -295,6 +291,15 @@
* ------
* Invoke the current Cx state to put the processor to sleep.
*/
+ if (cx->type == ACPI_STATE_C2 || cx->type == ACPI_STATE_C3) {
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb__after_clear_bit();
+ if (need_resched()) {
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ return;
+ }
+ }
+
switch (cx->type) {
case ACPI_STATE_C1:
@@ -327,6 +332,7 @@
t2 = inl(acpi_fadt.xpm_tmr_blk.address);
/* Re-enable interrupts */
local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
/* Compute time (ticks) that we were actually asleep */
sleep_ticks =
ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;
@@ -366,6 +372,7 @@
/* Re-enable interrupts */
local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
/* Compute time (ticks) that we were actually asleep */
sleep_ticks =
ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;
