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sched: Kill task_preempt_count() 

task_preempt_count() is pointless if preemption counter is per-cpu,
currently this is x86 only. It is only valid if the task is not
running, and even in this case the only info it can provide is the
state of PREEMPT_ACTIVE bit.

Change its single caller to check p->on_rq instead, this should be
the same if p->state != TASK_RUNNING, and kill this helper.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Alexander Graf <agraf@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/20141008183348.GC17495@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Oleg Nesterov 2014-10-08 20:33:48 +02:00 committed by Ingo Molnar
parent dfa50b605c
commit e2336f6e51
3 changed files with 1 additions and 7 deletions
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3
arch/x86/include/asm/preempt.h
View File

@ -30,9 +30,6 @@ static __always_inline void preempt_count_set(int pc)
/* /*
* must be macros to avoid header recursion hell * must be macros to avoid header recursion hell
*/ */
#define task_preempt_count(p) \
(task_thread_info(p)->saved_preempt_count & ~PREEMPT_NEED_RESCHED)
#define init_task_preempt_count(p) do { \ #define init_task_preempt_count(p) do { \
task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \ task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \
} while (0) } while (0)

3
include/asm-generic/preempt.h
View File

@ -23,9 +23,6 @@ static __always_inline void preempt_count_set(int pc)
/* /*
* must be macros to avoid header recursion hell * 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 { \ #define init_task_preempt_count(p) do { \
task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \ task_thread_info(p)->preempt_count = PREEMPT_DISABLED; \
} while (0) } while (0)

2
kernel/sched/core.c
View File

@ -1054,7 +1054,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
* ttwu() will sort out the placement. * ttwu() will sort out the placement.
*/ */
WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING && WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
!(task_preempt_count(p) & PREEMPT_ACTIVE)); !p->on_rq);
#ifdef CONFIG_LOCKDEP #ifdef CONFIG_LOCKDEP
/* /*