Re: [Fwd: [patch] intel_idle: Delete meaninglesslocal_irq_disable() call in intel_idle.c.]
From: Andrew Morton
Date: Tue Dec 27 2011 - 19:10:36 EST
On Mon, 26 Dec 2011 09:28:20 +0800
Yanmin Zhang <yanmin_zhang@xxxxxxxxxxxxxxx> wrote:
> Would you like to accept the patch into your testing tree?
hm, that's three indel_idle patches which I have now. Someone wake up
> intel_idle.c is a bit misleading in a sense that local_irq_disable,it
> actually does nothing. Real irq disable happens earlier in process_32.c:cpu_idle.
> Basically, cpuidle_state->enter is called, cpu irq is disabled.
> cpuidle_state->enter would turn on irq when exiting.
> intel_idle doesn't follow this assumption. Although it doesn't
> cause real issue, it misleads developers. Below patch deletes
> the calling to local_irq_disable() at entry.
> Signed-off-by: mzha38X <mingmingx.zhang@xxxxxxxxx>
> drivers/idle/intel_idle.c | 2 --
> 1 files changed, 0 insertions(+), 2 deletions(-)
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 5d2f8e1..28f0394 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -247,8 +247,6 @@ static int intel_idle(struct cpuidle_device *dev,
> cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
> - local_irq_disable();
> * leave_mm() to avoid costly and often unnecessary wakeups
> * for flushing the user TLB's associated with the active mm.
I'd suggest adding this as well:
@@ -232,6 +232,7 @@ static int get_driver_data(int cstate)
* @drv: cpuidle driver
* @index: index of cpuidle state
+ * Must be called under local_irq_disable().
static int intel_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/