Commit e9a8e01f authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: Clean up enum work_bits and related constants 



The bits of work->data are used for a few different purposes. How the bits
are used is determined by enum work_bits. The planned disable/enable support
will add another use, so let's clean it up a bit in preparation.

- Let WORK_STRUCT_*_BIT's values be determined by enum definition order.

- Deliminate different bit sections the same way using SHIFT and BITS
  values.

- Rename __WORK_OFFQ_CANCELING to WORK_OFFQ_CANCELING_BIT for consistency.

- Introduce WORK_STRUCT_PWQ_SHIFT and replace WORK_STRUCT_FLAG_MASK and
  WORK_STRUCT_WQ_DATA_MASK with WQ_STRUCT_PWQ_MASK for clarity.

- Improve documentation.

No functional changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarLai Jiangshan <jiangshanlai@gmail.com>
parent c5f5b942

include/linux/workqueue.h

+32 −26
Original line number Diff line number Diff line
@@ -24,41 +24,49 @@ 


enum work_bits {

	WORK_STRUCT_PENDING_BIT	= 0,	/* work item is pending execution */

	WORK_STRUCT_INACTIVE_BIT= 1,	/* work item is inactive */

	WORK_STRUCT_PWQ_BIT	= 2,	/* data points to pwq */

	WORK_STRUCT_LINKED_BIT	= 3,	/* next work is linked to this one */

	WORK_STRUCT_INACTIVE_BIT,	/* work item is inactive */

	WORK_STRUCT_PWQ_BIT,		/* data points to pwq */

	WORK_STRUCT_LINKED_BIT,		/* next work is linked to this one */

#ifdef CONFIG_DEBUG_OBJECTS_WORK

	WORK_STRUCT_STATIC_BIT	= 4,	/* static initializer (debugobjects) */

	WORK_STRUCT_COLOR_SHIFT	= 5,	/* color for workqueue flushing */

#else

	WORK_STRUCT_COLOR_SHIFT	= 4,	/* color for workqueue flushing */

	WORK_STRUCT_STATIC_BIT,		/* static initializer (debugobjects) */

#endif

	WORK_STRUCT_FLAG_BITS,



	/* color for workqueue flushing */

	WORK_STRUCT_COLOR_SHIFT	= WORK_STRUCT_FLAG_BITS,

	WORK_STRUCT_COLOR_BITS	= 4,



	/*

	 * Reserve 8 bits off of pwq pointer w/ debugobjects turned off.

	 * This makes pwqs aligned to 256 bytes and allows 16 workqueue

	 * flush colors.

	 * When WORK_STRUCT_PWQ is set, reserve 8 bits off of pwq pointer w/

	 * debugobjects turned off. This makes pwqs aligned to 256 bytes (512

	 * bytes w/ DEBUG_OBJECTS_WORK) and allows 16 workqueue flush colors.

	 *

	 * MSB

	 * [ pwq pointer ] [ flush color ] [ STRUCT flags ]

	 *                     4 bits        4 or 5 bits

	 */

	WORK_STRUCT_FLAG_BITS	= WORK_STRUCT_COLOR_SHIFT +

				  WORK_STRUCT_COLOR_BITS,

	WORK_STRUCT_PWQ_SHIFT	= WORK_STRUCT_COLOR_SHIFT + WORK_STRUCT_COLOR_BITS,



	/* data contains off-queue information when !WORK_STRUCT_PWQ */

	WORK_OFFQ_FLAG_BASE	= WORK_STRUCT_COLOR_SHIFT,



	__WORK_OFFQ_CANCELING	= WORK_OFFQ_FLAG_BASE,

	/*

	 * data contains off-queue information when !WORK_STRUCT_PWQ.

	 *

	 * MSB

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

	 *                 1 bit        4 or 5 bits

	 */

	WORK_OFFQ_FLAG_SHIFT	= WORK_STRUCT_FLAG_BITS,

	WORK_OFFQ_CANCELING_BIT = WORK_OFFQ_FLAG_SHIFT,

	WORK_OFFQ_FLAG_END,

	WORK_OFFQ_FLAG_BITS	= WORK_OFFQ_FLAG_END - WORK_OFFQ_FLAG_SHIFT,



	/*

	 * When a work item is off queue, its high bits point to the last

	 * pool it was on.  Cap at 31 bits and use the highest number to

	 * indicate that no pool is associated.

	 * When a work item is off queue, the high bits encode off-queue flags

	 * and the last pool it was on. Cap pool ID to 31 bits and use the

	 * highest number to indicate that no pool is associated.

	 */

	WORK_OFFQ_FLAG_BITS	= 1,

	WORK_OFFQ_POOL_SHIFT	= WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,

	WORK_OFFQ_POOL_SHIFT	= WORK_OFFQ_FLAG_SHIFT + WORK_OFFQ_FLAG_BITS,

	WORK_OFFQ_LEFT		= BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,

	WORK_OFFQ_POOL_BITS	= WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,



};



enum work_flags {
@@ -88,12 +96,10 @@ enum wq_misc_consts { 
};



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

#define WORK_OFFQ_CANCELING	(1ul << __WORK_OFFQ_CANCELING)

#define WORK_OFFQ_CANCELING	(1ul << WORK_OFFQ_CANCELING_BIT)

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

#define WORK_STRUCT_NO_POOL	(WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT)



#define WORK_STRUCT_FLAG_MASK    ((1ul << WORK_STRUCT_FLAG_BITS) - 1)

#define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)

#define WORK_STRUCT_PWQ_MASK	(~((1ul << WORK_STRUCT_PWQ_SHIFT) - 1))



#define WORK_DATA_INIT()	ATOMIC_LONG_INIT((unsigned long)WORK_STRUCT_NO_POOL)

#define WORK_DATA_STATIC_INIT()	\

kernel/workqueue.c

+4 −4
Original line number Diff line number Diff line
@@ -247,7 +247,7 @@ enum pool_workqueue_stats { 
};



/*

 * The per-pool workqueue.  While queued, the lower WORK_STRUCT_FLAG_BITS

 * The per-pool workqueue.  While queued, bits below WORK_PWQ_SHIFT

 * of work_struct->data are used for flags and the remaining high bits

 * point to the pwq; thus, pwqs need to be aligned at two's power of the

 * number of flag bits.
@@ -294,7 +294,7 @@ struct pool_workqueue { 
	 */

	struct kthread_work	release_work;

	struct rcu_head		rcu;

} __aligned(1 << WORK_STRUCT_FLAG_BITS);

} __aligned(1 << WORK_STRUCT_PWQ_SHIFT);



/*

 * Structure used to wait for workqueue flush.
@@ -843,7 +843,7 @@ static void clear_work_data(struct work_struct *work) 


static inline struct pool_workqueue *work_struct_pwq(unsigned long data)

{

	return (struct pool_workqueue *)(data & WORK_STRUCT_WQ_DATA_MASK);

	return (struct pool_workqueue *)(data & WORK_STRUCT_PWQ_MASK);

}



static struct pool_workqueue *get_work_pwq(struct work_struct *work)
@@ -4851,7 +4851,7 @@ static void pwq_release_workfn(struct kthread_work *work) 
static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,

		     struct worker_pool *pool)

{

	BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);

	BUG_ON((unsigned long)pwq & ~WORK_STRUCT_PWQ_MASK);



	memset(pwq, 0, sizeof(*pwq));