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Merge branch 'core/rcu' into sched/core, to pick up dependency

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We are going to rely on the loosening of RCU callback semantics,
introduced by this commit:

  806f04e9fd: ("rcu: Allow for smp_call_function() running callbacks from idle")

Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar
2020-05-28 10:52:53 +02:00
parent 498bdcdb94 806f04e9fd
commit 58ef57b16d
68 changed files with 2522 additions and 934 deletions
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48
kernel/sched/core.c
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@@ -2578,6 +2578,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
*
* Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
* __schedule(). See the comment for smp_mb__after_spinlock().
*
* A similar smb_rmb() lives in try_invoke_on_locked_down_task().
*/
smp_rmb();
if (p->on_rq && ttwu_remote(p, wake_flags))
@@ -2653,6 +2655,52 @@ out:
return success;
}
/**
* try_invoke_on_locked_down_task - Invoke a function on task in fixed state
* @p: Process for which the function is to be invoked.
* @func: Function to invoke.
* @arg: Argument to function.
*
* If the specified task can be quickly locked into a definite state
* (either sleeping or on a given runqueue), arrange to keep it in that
* state while invoking @func(@arg). This function can use ->on_rq and
* task_curr() to work out what the state is, if required. Given that
* @func can be invoked with a runqueue lock held, it had better be quite
* lightweight.
*
* Returns:
* @false if the task slipped out from under the locks.
* @true if the task was locked onto a runqueue or is sleeping.
* However, @func can override this by returning @false.
*/
bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
{
bool ret = false;
struct rq_flags rf;
struct rq *rq;
lockdep_assert_irqs_enabled();
raw_spin_lock_irq(&p->pi_lock);
if (p->on_rq) {
rq = __task_rq_lock(p, &rf);
if (task_rq(p) == rq)
ret = func(p, arg);
rq_unlock(rq, &rf);
} else {
switch (p->state) {
case TASK_RUNNING:
case TASK_WAKING:
break;
default:
smp_rmb(); // See smp_rmb() comment in try_to_wake_up().
if (!p->on_rq)
ret = func(p, arg);
}
}
raw_spin_unlock_irq(&p->pi_lock);
return ret;
}
/**
* wake_up_process - Wake up a specific process
* @p: The process to be woken up.