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| author | Peter Zijlstra <peterz@infradead.org> | 2015-09-28 17:52:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-10-06 17:08:14 +0200 |
| commit | 609ca066386b2e64d4c0b0f55da327654962a0c9 (patch) | |
| tree | 11b4faacc00bbc39d967374df633f6c352ce199b /include/asm-generic/preempt.h | |
| parent | sched/core: Rework TASK_DEAD preemption exception (diff) | |
| download | linux-609ca066386b2e64d4c0b0f55da327654962a0c9.tar.xz linux-609ca066386b2e64d4c0b0f55da327654962a0c9.zip | |
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/preempt.h')
| -rw-r--r-- | include/asm-generic/preempt.h | 2 |
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 { \ |