The patch titled
Subject: fs/epoll: loosen irq safety in epoll_insert() and epoll_remove()
has been added to the -mm tree. Its filename is
fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: fs/epoll: loosen irq safety in epoll_insert() and epoll_remove()
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/20180720172956.2883-3-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/eventpoll.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff -puN fs/eventpoll.c~fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove fs/eventpoll.c
--- a/fs/eventpoll.c~fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove
+++ a/fs/eventpoll.c
@@ -762,7 +762,6 @@ static void epi_rcu_free(struct rcu_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 *e
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 *e
{
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 *e
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 *e
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));
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
ipc-sem-prevent-queuestatus-tearing-in-semop.patch
fs-epoll-loosen-irq-safety-in-ep_scan_ready_list.patch
fs-epoll-loosen-irq-safety-in-epoll_insert-and-epoll_remove.patch
ipc-drop-ipc_lock.patch
lib-rhashtable-simplify-bucket_table_alloc.patch
lib-rhashtable-guarantee-initial-hashtable-allocation.patch
ipc-get-rid-of-ids-tables_initialized-hack.patch
ipc-simplify-ipc-initialization.patch
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