Commit 456a78ee authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: Remember whether a work item was on a BH workqueue 



Add an off-queue flag, WORK_OFFQ_BH, that indicates whether the last
workqueue the work item was on was a BH one. This will be used to test
whether a work item is BH in cancel_sync path to implement atomic
cancel_sync'ing for BH work items.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <jiangshanlai@gmail.com>
parent f09b10b6

include/linux/workqueue.h

+3 −1
Original line number Diff line number Diff line
@@ -52,9 +52,10 @@ enum work_bits { 
	 *

	 * MSB

	 * [ pool ID ] [ disable depth ] [ OFFQ flags ] [ STRUCT flags ]

	 *                  16 bits          0 bits       4 or 5 bits

	 *                  16 bits          1 bit        4 or 5 bits

	 */

	WORK_OFFQ_FLAG_SHIFT	= WORK_STRUCT_FLAG_BITS,

	WORK_OFFQ_BH_BIT	= WORK_OFFQ_FLAG_SHIFT,

	WORK_OFFQ_FLAG_END,

	WORK_OFFQ_FLAG_BITS	= WORK_OFFQ_FLAG_END - WORK_OFFQ_FLAG_SHIFT,
@@ -98,6 +99,7 @@ enum wq_misc_consts { 
};



/* Convenience constants - of type 'unsigned long', not 'enum'! */

#define WORK_OFFQ_BH		(1ul << WORK_OFFQ_BH_BIT)

#define WORK_OFFQ_FLAG_MASK	(((1ul << WORK_OFFQ_FLAG_BITS) - 1) << WORK_OFFQ_FLAG_SHIFT)

#define WORK_OFFQ_DISABLE_MASK	(((1ul << WORK_OFFQ_DISABLE_BITS) - 1) << WORK_OFFQ_DISABLE_SHIFT)

#define WORK_OFFQ_POOL_NONE	((1ul << WORK_OFFQ_POOL_BITS) - 1)

kernel/workqueue.c

+8 −2
Original line number Diff line number Diff line
@@ -764,6 +764,11 @@ static int work_next_color(int color) 
	return (color + 1) % WORK_NR_COLORS;

}



static unsigned long pool_offq_flags(struct worker_pool *pool)

{

	return (pool->flags & POOL_BH) ? WORK_OFFQ_BH : 0;

}



/*

 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data

 * contain the pointer to the queued pwq.  Once execution starts, the flag
@@ -2122,7 +2127,8 @@ static int try_to_grab_pending(struct work_struct *work, u32 cflags, 
		 * this destroys work->data needed by the next step, stash it.

		 */

		work_data = *work_data_bits(work);

		set_work_pool_and_keep_pending(work, pool->id, 0);

		set_work_pool_and_keep_pending(work, pool->id,

					       pool_offq_flags(pool));



		/* must be the last step, see the function comment */

		pwq_dec_nr_in_flight(pwq, work_data);
@@ -3175,7 +3181,7 @@ __acquires(&pool->lock) 
	 * PENDING and queued state changes happen together while IRQ is

	 * disabled.

	 */

	set_work_pool_and_clear_pending(work, pool->id, 0);

	set_work_pool_and_clear_pending(work, pool->id, pool_offq_flags(pool));



	pwq->stats[PWQ_STAT_STARTED]++;

	raw_spin_unlock_irq(&pool->lock);