Commit c04507ac authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

sched: Provide and use set_need_resched_current() 



set_tsk_need_resched(current) requires set_preempt_need_resched(current) to
work correctly outside of the scheduler.

Provide set_need_resched_current() which wraps this correctly and replace
all the open coded instances.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251116174750.665769842@linutronix.de
parent 33cf66d8

arch/s390/mm/pfault.c

+1 −2
Original line number Diff line number Diff line
@@ -199,8 +199,7 @@ static void pfault_interrupt(struct ext_code ext_code, 
			 * return to userspace schedule() to block.

			 */

			__set_current_state(TASK_UNINTERRUPTIBLE);

			set_tsk_need_resched(tsk);

			set_preempt_need_resched();

			set_need_resched_current();

		}

	}

out:

include/linux/sched.h

+7 −0
Original line number Diff line number Diff line
@@ -2058,6 +2058,13 @@ static inline int test_tsk_need_resched(struct task_struct *tsk) 
	return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));

}



static inline void set_need_resched_current(void)

{

	lockdep_assert_irqs_disabled();

	set_tsk_need_resched(current);

	set_preempt_need_resched();

}



/*

 * cond_resched() and cond_resched_lock(): latency reduction via

 * explicit rescheduling in places that are safe. The return

kernel/rcu/tiny.c

+3 −5
Original line number Diff line number Diff line
@@ -70,12 +70,10 @@ void rcu_qs(void) 
 */

void rcu_sched_clock_irq(int user)

{

	if (user) {

	if (user)

		rcu_qs();

	} else if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {

		set_tsk_need_resched(current);

		set_preempt_need_resched();

	}

	else if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail)

		set_need_resched_current();

}



/*

kernel/rcu/tree.c

+5 −9
Original line number Diff line number Diff line
@@ -2696,10 +2696,8 @@ void rcu_sched_clock_irq(int user) 
	/* The load-acquire pairs with the store-release setting to true. */

	if (smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {

		/* Idle and userspace execution already are quiescent states. */

		if (!rcu_is_cpu_rrupt_from_idle() && !user) {

			set_tsk_need_resched(current);

			set_preempt_need_resched();

		}

		if (!rcu_is_cpu_rrupt_from_idle() && !user)

			set_need_resched_current();

		__this_cpu_write(rcu_data.rcu_urgent_qs, false);

	}

	rcu_flavor_sched_clock_irq(user);
@@ -2824,7 +2822,6 @@ static void strict_work_handler(struct work_struct *work) 
/* Perform RCU core processing work for the current CPU.  */

static __latent_entropy void rcu_core(void)

{

	unsigned long flags;

	struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);

	struct rcu_node *rnp = rdp->mynode;
@@ -2837,8 +2834,8 @@ static __latent_entropy void rcu_core(void) 
	if (IS_ENABLED(CONFIG_PREEMPT_COUNT) && (!(preempt_count() & PREEMPT_MASK))) {

		rcu_preempt_deferred_qs(current);

	} else if (rcu_preempt_need_deferred_qs(current)) {

		set_tsk_need_resched(current);

		set_preempt_need_resched();

		guard(irqsave)();

		set_need_resched_current();

	}



	/* Update RCU state based on any recent quiescent states. */
@@ -2847,10 +2844,9 @@ static __latent_entropy void rcu_core(void) 
	/* No grace period and unregistered callbacks? */

	if (!rcu_gp_in_progress() &&

	    rcu_segcblist_is_enabled(&rdp->cblist) && !rcu_rdp_is_offloaded(rdp)) {

		local_irq_save(flags);

		guard(irqsave)();

		if (!rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))

			rcu_accelerate_cbs_unlocked(rnp, rdp);

		local_irq_restore(flags);

	}



	rcu_check_gp_start_stall(rnp, rdp, rcu_jiffies_till_stall_check());

kernel/rcu/tree_exp.h

+1 −2
Original line number Diff line number Diff line
@@ -729,8 +729,7 @@ static void rcu_exp_need_qs(void) 
	__this_cpu_write(rcu_data.cpu_no_qs.b.exp, true);

	/* Store .exp before .rcu_urgent_qs. */

	smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true);

	set_tsk_need_resched(current);

	set_preempt_need_resched();

	set_need_resched_current();

}



#ifdef CONFIG_PREEMPT_RCU