Commit bdf8b9bf authored by Tejun Heo's avatar Tejun Heo
Browse files

workqueue: Improve locking rule description for worker fields 



* Some worker fields are modified only by the worker itself while holding
  pool->lock thus making them safe to read from self, IRQ context if the CPU
  is running the worker or while holding pool->lock. Add 'K' locking rule
  for them.

* worker->sleeping is currently marked "None" which isn't very descriptive.
  It's used only by the worker itself. Add 'S' locking rule for it.

A future patch will depend on the 'K' rule to access worker->current_* from
the scheduler ticks.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent c54d5046

kernel/workqueue.c

+6 −0
Original line number Diff line number Diff line
@@ -126,6 +126,12 @@ enum { 
 *    cpu or grabbing pool->lock is enough for read access.  If

 *    POOL_DISASSOCIATED is set, it's identical to L.

 *

 * K: Only modified by worker while holding pool->lock. Can be safely read by

 *    self, while holding pool->lock or from IRQ context if %current is the

 *    kworker.

 *

 * S: Only modified by worker self.

 *

 * A: wq_pool_attach_mutex protected.

 *

 * PL: wq_pool_mutex protected.

kernel/workqueue_internal.h

+8 −7
Original line number Diff line number Diff line
@@ -28,14 +28,15 @@ struct worker { 
		struct hlist_node	hentry;	/* L: while busy */

	};



	struct work_struct	*current_work;	/* L: work being processed */

	work_func_t		current_func;	/* L: current_work's fn */

	struct pool_workqueue	*current_pwq;	/* L: current_work's pwq */

	unsigned int		current_color;	/* L: current_work's color */

	int			sleeping;	/* None */

	struct work_struct	*current_work;	/* K: work being processed and its */

	work_func_t		current_func;	/* K: function */

	struct pool_workqueue	*current_pwq;	/* K: pwq */

	unsigned int		current_color;	/* K: color */



	int			sleeping;	/* S: is worker sleeping? */



	/* used by the scheduler to determine a worker's last known identity */

	work_func_t		last_func;	/* L: last work's fn */

	work_func_t		last_func;	/* K: last work's fn */



	struct list_head	scheduled;	/* L: scheduled works */
@@ -45,7 +46,7 @@ struct worker { 
	struct list_head	node;		/* A: anchored at pool->workers */

						/* A: runs through worker->node */



	unsigned long		last_active;	/* L: last active timestamp */

	unsigned long		last_active;	/* K: last active timestamp */

	unsigned int		flags;		/* X: flags */

	int			id;		/* I: worker id */