Commit 1b7af295 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Paul E. McKenney
Browse files

sched/core: Allow try_invoke_on_locked_down_task() with irqs disabled 

The try_invoke_on_locked_down_task() function currently requires
that interrupts be enabled, but it is called with interrupts
disabled from rcu_print_task_stall(), resulting in an "IRQs not
enabled as expected" diagnostic.  This commit therefore updates
try_invoke_on_locked_down_task() to use raw_spin_lock_irqsave() instead
of raw_spin_lock_irq(), thus allowing use from either context.

Link: https://lore.kernel.org/lkml/000000000000903d5805ab908fc4@google.com/
Link: https://lore.kernel.org/lkml/20200928075729.GC2611@hirez.programming.kicks-ass.net/


Reported-by: default avatar <syzbot+cb3b69ae80afd6535b0e@syzkaller.appspotmail.com>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 1b04fa99

kernel/sched/core.c

+4 −5
Original line number Diff line number Diff line
@@ -2989,7 +2989,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 


/**

 * try_invoke_on_locked_down_task - Invoke a function on task in fixed state

 * @p: Process for which the function is to be invoked.

 * @p: Process for which the function is to be invoked, can be @current.

 * @func: Function to invoke.

 * @arg: Argument to function.

 *
@@ -3007,12 +3007,11 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) 
 */

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;

	bool ret = false;

	struct rq *rq;



	lockdep_assert_irqs_enabled();

	raw_spin_lock_irq(&p->pi_lock);

	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);

	if (p->on_rq) {

		rq = __task_rq_lock(p, &rf);

		if (task_rq(p) == rq)
@@ -3029,7 +3028,7 @@ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct t 
				ret = func(p, arg);

		}

	}

	raw_spin_unlock_irq(&p->pi_lock);

	raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);

	return ret;

}