*
* 1) epmutex (mutex)
* 2) ep->mtx (mutex)
- * 3) ep->lock (spinlock)
+ * 3) ep->wq.lock (spinlock)
*
* The acquire order is the one listed above, from 1 to 3.
- * We need a spinlock (ep->lock) because we manipulate objects
+ * We need a spinlock (ep->wq.lock) because we manipulate objects
* from inside the poll callback, that might be triggered from
* a wake_up() that in turn might be called from IRQ context.
* So we can't sleep inside the poll callback and hence we need
* of epoll file descriptors, we use the current recursion depth as
* the lockdep subkey.
* It is possible to drop the "ep->mtx" and to use the global
- * mutex "epmutex" (together with "ep->lock") to have it working,
+ * mutex "epmutex" (together with "ep->wq.lock") to have it working,
* but having "ep->mtx" will make the interface more scalable.
* Events that require holding "epmutex" are very rare, while for
* normal operations the epoll private "ep->mtx" will guarantee
* This structure is stored inside the "private_data" member of the file
* structure and represents the main data structure for the eventpoll
* interface.
+ *
+ * Access to it is protected by the lock inside wq.
*/
struct eventpoll {
- /* Protect the access to this structure */
- spinlock_t lock;
-
/*
* This mutex is used to ensure that files are not removed
* while epoll is using them. This is held during the event
/*
* This is a single linked list that chains all the "struct epitem" that
* happened while transferring ready events to userspace w/out
- * holding ->lock.
+ * holding ->wq.lock.
*/
struct epitem *ovflist;
* because we want the "sproc" callback to be able to do it
* in a lockless way.
*/
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
list_splice_init(&ep->rdllist, &txlist);
ep->ovflist = NULL;
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
/*
* Now call the callback function.
*/
res = (*sproc)(ep, &txlist, priv);
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
/*
* During the time we spent inside the "sproc" callback, some
* other events might have been queued by the poll callback.
if (waitqueue_active(&ep->poll_wait))
pwake++;
}
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
if (!ep_locked)
mutex_unlock(&ep->mtx);
struct file *file = epi->ffd.file;
/*
- * Removes poll wait queue hooks. We _have_ to do this without holding
- * the "ep->lock" otherwise a deadlock might occur. This because of the
- * sequence of the lock acquisition. Here we do "ep->lock" then the wait
- * queue head lock when unregistering the wait queue. The wakeup callback
- * will run by holding the wait queue head lock and will call our callback
- * that will try to get "ep->lock".
+ * Removes poll wait queue hooks.
*/
ep_unregister_pollwait(ep, epi);
rb_erase_cached(&epi->rbn, &ep->rbr);
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
if (ep_is_linked(&epi->rdllink))
list_del_init(&epi->rdllink);
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
wakeup_source_unregister(ep_wakeup_source(epi));
/*
* Walks through the whole tree by freeing each "struct epitem". At this
* point we are sure no poll callbacks will be lingering around, and also by
* holding "epmutex" we can be sure that no file cleanup code will hit
- * us during this operation. So we can avoid the lock on "ep->lock".
+ * us during this operation. So we can avoid the lock on "ep->wq.lock".
* We do not need to lock ep->mtx, either, we only do it to prevent
* a lockdep warning.
*/
if (unlikely(!ep))
goto free_uid;
- spin_lock_init(&ep->lock);
mutex_init(&ep->mtx);
init_waitqueue_head(&ep->wq);
init_waitqueue_head(&ep->poll_wait);
__poll_t pollflags = key_to_poll(key);
int ewake = 0;
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
ep_set_busy_poll_napi_id(epi);
pwake++;
out_unlock:
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
/* We have to call this outside the lock */
if (pwake)
goto error_remove_epi;
/* We have to drop the new item inside our item list to keep track of it */
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
/* record NAPI ID of new item if present */
ep_set_busy_poll_napi_id(epi);
pwake++;
}
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
atomic_long_inc(&ep->user->epoll_watches);
* list, since that is used/cleaned only inside a section bound by "mtx".
* And ep_insert() is called with "mtx" held.
*/
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
if (ep_is_linked(&epi->rdllink))
list_del_init(&epi->rdllink);
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
wakeup_source_unregister(ep_wakeup_source(epi));
* 1) Flush epi changes above to other CPUs. This ensures
* we do not miss events from ep_poll_callback if an
* event occurs immediately after we call f_op->poll().
- * We need this because we did not take ep->lock while
+ * We need this because we did not take ep->wq.lock while
* changing epi above (but ep_poll_callback does take
- * ep->lock).
+ * ep->wq.lock).
*
* 2) We also need to ensure we do not miss _past_ events
* when calling f_op->poll(). This barrier also
* list, push it inside.
*/
if (ep_item_poll(epi, &pt, 1)) {
- spin_lock_irq(&ep->lock);
+ spin_lock_irq(&ep->wq.lock);
if (!ep_is_linked(&epi->rdllink)) {
list_add_tail(&epi->rdllink, &ep->rdllist);
ep_pm_stay_awake(epi);
if (waitqueue_active(&ep->poll_wait))
pwake++;
}
- spin_unlock_irq(&ep->lock);
+ spin_unlock_irq(&ep->wq.lock);
}
/* We have to call this outside the lock */
* caller specified a non blocking operation.
*/
timed_out = 1;
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
goto check_events;
}
if (!ep_events_available(ep))
ep_busy_loop(ep, timed_out);
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
if (!ep_events_available(ep)) {
/*
break;
}
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS))
timed_out = 1;
- spin_lock_irqsave(&ep->lock, flags);
+ spin_lock_irqsave(&ep->wq.lock, flags);
}
__remove_wait_queue(&ep->wq, &wait);
/* Is it worth to try to dig for events ? */
eavail = ep_events_available(ep);
- spin_unlock_irqrestore(&ep->lock, flags);
+ spin_unlock_irqrestore(&ep->wq.lock, flags);
/*
* Try to transfer events to user space. In case we get 0 events and
projects / mirror_ubuntu-eoan-kernel.git / commitdiff