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authorPeter Zijlstra <peterz@infradead.org>2015-09-28 17:52:18 +0200
committerIngo Molnar <mingo@kernel.org>2015-10-06 17:08:14 +0200
commit609ca066386b2e64d4c0b0f55da327654962a0c9 (patch)
tree11b4faacc00bbc39d967374df633f6c352ce199b /include/asm-generic
parentb99def8b961448f5b9a550dddeeb718e3975e7a6 (diff)
sched/core: Create preempt_count invariant
Assuming units of PREEMPT_DISABLE_OFFSET for preempt_count() numbers. Now that TASK_DEAD no longer results in preempt_count() == 3 during scheduling, we will always call context_switch() with preempt_count() == 2. However, we don't always end up with preempt_count() == 2 in finish_task_switch() because new tasks get created with preempt_count() == 1. Create FORK_PREEMPT_COUNT and set it to 2 and use that in the right places. Note that we cannot use INIT_PREEMPT_COUNT as that serves another purpose (boot). After this, preempt_count() is invariant across the context switch, with exception of PREEMPT_ACTIVE. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/preempt.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h
index 0bec580a4885..5d8ffa3e6f8c 100644
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -24,7 +24,7 @@ static __always_inline void preempt_count_set(int pc)
* must be macros to avoid header recursion hell
*/
#define init_task_preempt_count(p) do { \
- task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
+ task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
} while (0)
#define init_idle_preempt_count(p, cpu) do { \

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