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Commit 2a298a35 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

[PATCH] Fix TIF_POLLING_NRFLAG in ACPI idle routines 



Commit 64c7c8f8 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: default avatarLinus Torvalds <torvalds@osdl.org>
parent deda4987

drivers/acpi/processor_idle.c

+14 −7
Original line number Original line Diff line number Diff line
@@ -169,14 +169,10 @@ acpi_processor_power_activate(struct acpi_processor *pr, 




static void acpi_safe_halt(void)

static void acpi_safe_halt(void)

{

{

	int polling = test_thread_flag(TIF_POLLING_NRFLAG);

	if (polling) {

	clear_thread_flag(TIF_POLLING_NRFLAG);

	clear_thread_flag(TIF_POLLING_NRFLAG);

	smp_mb__after_clear_bit();

	smp_mb__after_clear_bit();

	}

	if (!need_resched())

	if (!need_resched())

		safe_halt();

		safe_halt();

	if (polling)

	set_thread_flag(TIF_POLLING_NRFLAG);

	set_thread_flag(TIF_POLLING_NRFLAG);

}

}
@@ -295,6 +291,15 @@ static void acpi_processor_idle(void) 
	 * ------

	 * ------

	 * Invoke the current Cx state to put the processor to sleep.

	 * 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) {

	switch (cx->type) {





	case ACPI_STATE_C1:

	case ACPI_STATE_C1:
@@ -327,6 +332,7 @@ static void acpi_processor_idle(void) 
		t2 = inl(acpi_fadt.xpm_tmr_blk.address);

		t2 = inl(acpi_fadt.xpm_tmr_blk.address);

		/* Re-enable interrupts */

		/* Re-enable interrupts */

		local_irq_enable();

		local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);

		/* Compute time (ticks) that we were actually asleep */

		/* Compute time (ticks) that we were actually asleep */

		sleep_ticks =

		sleep_ticks =

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;
@@ -366,6 +372,7 @@ static void acpi_processor_idle(void) 




		/* Re-enable interrupts */

		/* Re-enable interrupts */

		local_irq_enable();

		local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);

		/* Compute time (ticks) that we were actually asleep */

		/* Compute time (ticks) that we were actually asleep */

		sleep_ticks =

		sleep_ticks =

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;