Commit feb4a513 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
Browse files

irq_work: Slightly simplify IRQ_WORK_PENDING clearing 



Instead of fetching the value of flags and perform an xchg() to clear
a bit, just use atomic_fetch_andnot() that is more suitable to do that
job in one operation while keeping the full ordering.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191108160858.31665-4-frederic@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 25269871

kernel/irq_work.c

+3 −4
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ static bool irq_work_claim(struct irq_work *work) 
	oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags);

	/*

	 * If the work is already pending, no need to raise the IPI.

	 * The pairing atomic_xchg() in irq_work_run() makes sure

	 * The pairing atomic_fetch_andnot() in irq_work_run() makes sure

	 * everything we did before is visible.

	 */

	if (oflags & IRQ_WORK_PENDING)
@@ -135,7 +135,6 @@ static void irq_work_run_list(struct llist_head *list) 
{

	struct irq_work *work, *tmp;

	struct llist_node *llnode;

	int flags;



	BUG_ON(!irqs_disabled());
@@ -144,6 +143,7 @@ static void irq_work_run_list(struct llist_head *list) 


	llnode = llist_del_all(list);

	llist_for_each_entry_safe(work, tmp, llnode, llnode) {

		int flags;

		/*

		 * Clear the PENDING bit, after this point the @work

		 * can be re-used.
@@ -151,8 +151,7 @@ static void irq_work_run_list(struct llist_head *list) 
		 * to claim that work don't rely on us to handle their data

		 * while we are in the middle of the func.

		 */

		flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;

		atomic_xchg(&work->flags, flags);

		flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);



		work->func(work);

		/*

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