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author | Peter Zijlstra <peterz@infradead.org> | 2013-08-14 14:55:40 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2013-09-25 14:07:50 +0200 |
commit | a787870924dbd6f321661e06d4ec1c7a408c9ccf (patch) | |
tree | 43aae13f34d21b001efd4a4a4e64f3d085988bad /include/asm-generic | |
parent | f27dde8deef33c9e58027df11ceab2198601d6a6 (diff) | |
download | blackbird-op-linux-a787870924dbd6f321661e06d4ec1c7a408c9ccf.tar.gz blackbird-op-linux-a787870924dbd6f321661e06d4ec1c7a408c9ccf.zip |
sched, arch: Create asm/preempt.h
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>
Diffstat (limited to 'include/asm-generic')
-rw-r--r-- | include/asm-generic/preempt.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h new file mode 100644 index 000000000000..a1fc6590a743 --- /dev/null +++ b/include/asm-generic/preempt.h @@ -0,0 +1,54 @@ +#ifndef __ASM_PREEMPT_H +#define __ASM_PREEMPT_H + +#include <linux/thread_info.h> + +/* + * 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 ¤t_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); +} + +#endif /* __ASM_PREEMPT_H */ |