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>

diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 400873450e33ab86d734471e2f07fd0ed775dfa1..8f32718425339f426778bbe09e2c468e5ff63814 100644 (file)
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -30,9 +30,6 @@ static __always_inline void preempt_count_set(int pc)
 /*
  * 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 { \
        task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \
 } while (0)

diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h
index 1cd3f5d767a81b18b8c3950701506e3f8bfcfc6c..eb6f9e6c30756f5f39605582cf34c0e48c6a3df1 100644 (file)
--- a/include/asm-generic/preempt.h
+++ b/include/asm-generic/preempt.h
@@ -23,9 +23,6 @@ static __always_inline void preempt_count_set(int pc)
 /*
  * 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)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1b69603c1d3e8079596d3190272f203aef75e7d2..5c067fd66db92d70ec2a159699ee9e1adb1d4efe 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1054,7 +1054,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
         * ttwu() will sort out the placement.
         */
        WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
-                       !(task_preempt_count(p) & PREEMPT_ACTIVE));
+                       !p->on_rq);
 
 #ifdef CONFIG_LOCKDEP
        /*