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sched, arch: Create asm/preempt.h

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In order to prepare to per-arch implementations of preempt_count move
the required bits into an asm-generic header and use this for all
archs.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-h5j0c1r3e3fk015m30h8f1zx@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2013-08-14 14:55:40 +02:00
committed by Ingo Molnar
parent f27dde8dee
commit a787870924
32 changed files with 85 additions and 48 deletions
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49
include/linux/preempt.h
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@@ -6,7 +6,6 @@
* preempt_count (used for kernel preemption, interrupt count, etc.)
*/
#include <linux/thread_info.h>
#include <linux/linkage.h>
#include <linux/list.h>
@@ -16,53 +15,7 @@
*/
#define PREEMPT_NEED_RESCHED 0x80000000
/*
* We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users
* that think a non-zero value indicates we cannot preempt.
*/
static __always_inline int preempt_count(void)
{
return current_thread_info()->preempt_count & ~PREEMPT_NEED_RESCHED;
}
static __always_inline int *preempt_count_ptr(void)
{
return &current_thread_info()->preempt_count;
}
/*
* We now loose PREEMPT_NEED_RESCHED and cause an extra reschedule; however the
* alternative is loosing a reschedule. Better schedule too often -- also this
* should be a very rare operation.
*/
static __always_inline void preempt_count_set(int pc)
{
*preempt_count_ptr() = pc;
}
/*
* We fold the NEED_RESCHED bit into the preempt count such that
* preempt_enable() can decrement and test for needing to reschedule with a
* single instruction.
*
* We invert the actual bit, so that when the decrement hits 0 we know we both
* need to resched (the bit is cleared) and can resched (no preempt count).
*/
static __always_inline void set_preempt_need_resched(void)
{
*preempt_count_ptr() &= ~PREEMPT_NEED_RESCHED;
}
static __always_inline void clear_preempt_need_resched(void)
{
*preempt_count_ptr() |= PREEMPT_NEED_RESCHED;
}
static __always_inline bool test_preempt_need_resched(void)
{
return !(*preempt_count_ptr() & PREEMPT_NEED_RESCHED);
}
#include <asm/preempt.h>
#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
extern void add_preempt_count(int val);