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author | Oleg Nesterov <oleg@redhat.com> | 2014-10-09 21:32:32 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2014-10-28 10:47:55 +0100 |
commit | dfa50b605c2a933b7bb1c1d575a0da4e897e3c7d (patch) | |
tree | 9f7367d79ba89c8d151a19bedcfb373b90d2c941 /kernel/sched | |
parent | 1a43a14a5bd9c32dbd7af35e35a5afa703944bcb (diff) | |
download | linux-stable-dfa50b605c2a933b7bb1c1d575a0da4e897e3c7d.tar.gz linux-stable-dfa50b605c2a933b7bb1c1d575a0da4e897e3c7d.tar.bz2 linux-stable-dfa50b605c2a933b7bb1c1d575a0da4e897e3c7d.zip |
sched: Make finish_task_switch() return 'struct rq *'
Both callers of finish_task_switch() need to recalculate this_rq()
and pass it as an argument, plus __schedule() does this again after
context_switch().
It would be simpler to call this_rq() once in finish_task_switch()
and return the this rq to the callers.
Note: probably "int cpu" in __schedule() should die; it is not used
and both rcu_note_context_switch() and wq_worker_sleeping() do not
really need this argument.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20141009193232.GB5408@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 38 |
1 files changed, 15 insertions, 23 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index b4935600cd85..1b69603c1d3e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2220,7 +2220,6 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, /** * finish_task_switch - clean up after a task-switch - * @rq: runqueue associated with task-switch * @prev: the thread we just switched away from. * * finish_task_switch must be called after the context switch, paired @@ -2232,10 +2231,16 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, * so, we finish that here outside of the runqueue lock. (Doing it * with the lock held can cause deadlocks; see schedule() for * details.) + * + * The context switch have flipped the stack from under us and restored the + * local variables which were saved when this task called schedule() in the + * past. prev == current is still correct but we need to recalculate this_rq + * because prev may have moved to another CPU. */ -static void finish_task_switch(struct rq *rq, struct task_struct *prev) +static struct rq *finish_task_switch(struct task_struct *prev) __releases(rq->lock) { + struct rq *rq = this_rq(); struct mm_struct *mm = rq->prev_mm; long prev_state; @@ -2275,6 +2280,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) } tick_nohz_task_switch(current); + return rq; } #ifdef CONFIG_SMP @@ -2313,8 +2319,7 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) /* finish_task_switch() drops rq->lock and enables preemtion */ preempt_disable(); - rq = this_rq(); - finish_task_switch(rq, prev); + rq = finish_task_switch(prev); post_schedule(rq); preempt_enable(); @@ -2323,10 +2328,9 @@ asmlinkage __visible void schedule_tail(struct task_struct *prev) } /* - * context_switch - switch to the new MM and the new - * thread's register state. + * context_switch - switch to the new MM and the new thread's register state. */ -static inline void +static inline struct rq * context_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { @@ -2365,14 +2369,9 @@ context_switch(struct rq *rq, struct task_struct *prev, context_tracking_task_switch(prev, next); /* Here we just switch the register state and the stack. */ switch_to(prev, next, prev); - barrier(); - /* - * this_rq must be evaluated again because prev may have moved - * CPUs since it called schedule(), thus the 'rq' on its stack - * frame will be invalid. - */ - finish_task_switch(this_rq(), prev); + + return finish_task_switch(prev); } /* @@ -2854,15 +2853,8 @@ need_resched: rq->curr = next; ++*switch_count; - context_switch(rq, prev, next); /* unlocks the rq */ - /* - * The context switch have flipped the stack from under us - * and restored the local variables which were saved when - * this task called schedule() in the past. prev == current - * is still correct, but it can be moved to another cpu/rq. - */ - cpu = smp_processor_id(); - rq = cpu_rq(cpu); + rq = context_switch(rq, prev, next); /* unlocks the rq */ + cpu = cpu_of(rq); } else raw_spin_unlock_irq(&rq->lock); |