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workqueue: Improve locking rule description for worker fields

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* 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: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2023-05-17 17:02:08 -10:00
parent c54d5046a0
commit bdf8b9bfc1
2 changed files with 14 additions and 7 deletions
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6
kernel/workqueue.c
View File

@ -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.

15
kernel/workqueue_internal.h
View File

@ -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 */