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fs/epoll: loosen irq safety in epoll_insert() and epoll_remove()

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Both functions are similar to the context of ep_modify(), called via
epoll_ctl(2).  Just like ep_modify(), saving and restoring interrupts is
an overkill in these calls as it will never be called with irqs disabled.
While ep_remove() can be called directly from EPOLL_CTL_DEL, it can also
be called when releasing the file, but this also complies with the above.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Cc: Jason Baron <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Davidlohr Bueso authored and Linus Torvalds committed 2018-08-22 10:52:47 -07:00
1 parent 002b343669
commit 304b18b8d6
1 file changed
+6 -8
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fs/eventpoll.c
+6 -8
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@@ -762,7 +762,6 @@ static void epi_rcu_free(struct rcu_head *head)
*/
static int ep_remove(struct eventpoll *ep, struct epitem *epi)
{
unsigned long flags;
struct file *file = epi->ffd.file;
/*
@@ -777,10 +776,10 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
rb_erase_cached(&epi->rbn, &ep->rbr);
spin_lock_irqsave(&ep->wq.lock, flags);
spin_lock_irq(&ep->wq.lock);
if (ep_is_linked(&epi->rdllink))
list_del_init(&epi->rdllink);
spin_unlock_irqrestore(&ep->wq.lock, flags);
spin_unlock_irq(&ep->wq.lock);
wakeup_source_unregister(ep_wakeup_source(epi));
/*
@@ -1409,7 +1408,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
{
int error, pwake = 0;
__poll_t revents;
unsigned long flags;
long user_watches;
struct epitem *epi;
struct ep_pqueue epq;
@@ -1476,7 +1474,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
goto error_remove_epi;
/* We have to drop the new item inside our item list to keep track of it */
spin_lock_irqsave(&ep->wq.lock, flags);
spin_lock_irq(&ep->wq.lock);
/* record NAPI ID of new item if present */
ep_set_busy_poll_napi_id(epi);
@@ -1493,7 +1491,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
pwake++;
}
spin_unlock_irqrestore(&ep->wq.lock, flags);
spin_unlock_irq(&ep->wq.lock);
atomic_long_inc(&ep->user->epoll_watches);
@@ -1519,10 +1517,10 @@ error_unregister:
* 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->wq.lock, flags);
spin_lock_irq(&ep->wq.lock);
if (ep_is_linked(&epi->rdllink))
list_del_init(&epi->rdllink);
spin_unlock_irqrestore(&ep->wq.lock, flags);
spin_unlock_irq(&ep->wq.lock);
wakeup_source_unregister(ep_wakeup_source(epi));