On Wed, Apr 02, 2014 at 04:29:48PM -0700, David Cohen wrote:
> Hi,
>
> I've detected a regression from upstream (using an Intel Merrifield
> device) since 3.13 (still exists in 3.14) which I never had much time
> to start to investigate until now. The symptoms are: the device boots
> and works fine for while until it silently hangs.
>
> I finally bisected v3.12..v3.13 and found exactly which commit created
> the issue:
>
> commit f27dde8deef33c9e58027df11ceab2198601d6a6
> Author: Peter Zijlstra <[email protected]>
> Date: Wed Aug 14 14:55:31 2013 +0200
>
> sched: Add NEED_RESCHED to the preempt_count
FWIW I did further investigation and made the issue to go away with this
hack:
diff --git a/arch/x86/include/asm/preempt.h
b/arch/x86/include/asm/preempt.h
index c8b051933b1b..41744d99c88f 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -95,7 +95,7 @@ static __always_inline bool
__preempt_count_dec_and_test(void)
*/
static __always_inline bool should_resched(void)
{
- return unlikely(!__this_cpu_read_4(__preempt_count));
+ return unlikely(tif_need_resched());
}
#ifdef CONFIG_PREEMPT
--
I extended part of this patch to x86:
commit ba1f14fbe70965ae0fb1655a5275a62723f65b77
Author: Peter Zijlstra <[email protected]>
Date: Thu Nov 28 14:26:41 2013 +0100
sched: Remove PREEMPT_NEED_RESCHED from generic code
--
Br, David Cohen
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