sched: Create more preempt_count accessors
We need a few special preempt_count accessors:
- task_preempt_count() for when we're interested in the preemption
count of another (non-running) task.
- init_task_preempt_count() for properly initializing the preemption
count.
- init_idle_preempt_count() a special case of the above for the idle
threads.
With these no generic code ever touches thread_info::preempt_count
anymore and architectures could choose to remove it.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-jf5swrio8l78j37d06fzmo4r@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h
index a1fc659..8100b1e 100644
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -28,6 +28,20 @@
}
/*
+ * must be macros to avoid header recursion hell
+ */
+#define task_preempt_count(p) \
+ (task_thread_info(p)->preempt_count & ~PREEMPT_NEED_RESCHED)
+
+#define init_task_preempt_count(p) do { \
+ task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
+} while (0)
+
+#define init_idle_preempt_count(p, cpu) do { \
+ task_thread_info(p)->preempt_count = PREEMPT_ENABLED; \
+} while (0)
+
+/*
* 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.