From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Marc Zyngier <maz@kernel.org>
Subject: [RFC PATCH 19/27] ep_insert(): don't open-code ep_remove() on failure exits
Date: Sun, 4 Oct 2020 03:39:21 +0100 [thread overview]
Message-ID: <20201004023929.2740074-19-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20201004023929.2740074-1-viro@ZenIV.linux.org.uk>
From: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/eventpoll.c | 51 ++++++++++++++-------------------------------------
1 file changed, 14 insertions(+), 37 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index f9c567af1f5f..c987b61701e4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1384,12 +1384,16 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
epi->next = EP_UNACTIVE_PTR;
if (epi->event.events & EPOLLWAKEUP) {
error = ep_create_wakeup_source(epi);
- if (error)
- goto error_create_wakeup_source;
+ if (error) {
+ kmem_cache_free(epi_cache, epi);
+ return error;
+ }
} else {
RCU_INIT_POINTER(epi->ws, NULL);
}
+ atomic_long_inc(&ep->user->epoll_watches);
+
/* Add the current item to the list of active epoll hook for this file */
spin_lock(&tfile->f_lock);
list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
@@ -1402,9 +1406,10 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
ep_rbtree_insert(ep, epi);
/* now check if we've created too many backpaths */
- error = -EINVAL;
- if (full_check && reverse_path_check())
- goto error_remove_epi;
+ if (unlikely(full_check && reverse_path_check())) {
+ ep_remove(ep, epi);
+ return -EINVAL;
+ }
/* Initialize the poll table using the queue callback */
epq.epi = epi;
@@ -1424,9 +1429,10 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
* install process. Namely an allocation for a wait queue failed due
* high memory pressure.
*/
- error = -ENOMEM;
- if (!epq.epi)
- goto error_unregister;
+ if (unlikely(!epq.epi)) {
+ ep_remove(ep, epi);
+ return -ENOMEM;
+ }
/* We have to drop the new item inside our item list to keep track of it */
write_lock_irq(&ep->lock);
@@ -1448,40 +1454,11 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
write_unlock_irq(&ep->lock);
- atomic_long_inc(&ep->user->epoll_watches);
-
/* We have to call this outside the lock */
if (pwake)
ep_poll_safewake(ep, NULL);
return 0;
-
-error_unregister:
- ep_unregister_pollwait(ep, epi);
-error_remove_epi:
- spin_lock(&tfile->f_lock);
- list_del_rcu(&epi->fllink);
- spin_unlock(&tfile->f_lock);
-
- rb_erase_cached(&epi->rbn, &ep->rbr);
-
- /*
- * We need to do this because an event could have been arrived on some
- * allocated wait queue. Note that we don't care about the ep->ovflist
- * list, since that is used/cleaned only inside a section bound by "mtx".
- * And ep_insert() is called with "mtx" held.
- */
- write_lock_irq(&ep->lock);
- if (ep_is_linked(epi))
- list_del_init(&epi->rdllink);
- write_unlock_irq(&ep->lock);
-
- wakeup_source_unregister(ep_wakeup_source(epi));
-
-error_create_wakeup_source:
- kmem_cache_free(epi_cache, epi);
-
- return error;
}
/*
--
2.11.0
next prev parent reply other threads:[~2020-10-04 2:40 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-04 2:36 [RFC][PATCHSET] epoll cleanups Al Viro
2020-10-04 2:39 ` [RFC PATCH 01/27] epoll: switch epitem->pwqlist to single-linked list Al Viro
2020-10-04 2:39 ` [RFC PATCH 02/27] epoll: get rid of epitem->nwait Al Viro
2020-10-04 2:39 ` [RFC PATCH 03/27] untangling ep_call_nested(): get rid of useless arguments Al Viro
2020-10-04 2:39 ` [RFC PATCH 04/27] untangling ep_call_nested(): it's all serialized on epmutex Al Viro
2020-10-04 2:39 ` [RFC PATCH 05/27] untangling ep_call_nested(): take pushing cookie into a helper Al Viro
2020-10-04 2:39 ` [RFC PATCH 06/27] untangling ep_call_nested(): move push/pop of cookie into the callbacks Al Viro
2020-10-04 2:39 ` [RFC PATCH 07/27] untangling ep_call_nested(): and there was much rejoicing Al Viro
2020-10-04 2:39 ` [RFC PATCH 08/27] reverse_path_check_proc(): sane arguments Al Viro
2020-10-04 2:39 ` [RFC PATCH 09/27] reverse_path_check_proc(): don't bother with cookies Al Viro
2020-10-04 2:39 ` [RFC PATCH 10/27] clean reverse_path_check_proc() a bit Al Viro
2020-10-04 2:39 ` [RFC PATCH 11/27] ep_loop_check_proc(): lift pushing the cookie into callers Al Viro
2020-10-04 2:39 ` [RFC PATCH 12/27] get rid of ep_push_nested() Al Viro
2020-10-04 2:39 ` [RFC PATCH 13/27] ep_loop_check_proc(): saner calling conventions Al Viro
2020-10-04 2:39 ` [RFC PATCH 14/27] ep_scan_ready_list(): prepare to splitup Al Viro
2020-10-04 2:39 ` [RFC PATCH 15/27] lift the calls of ep_read_events_proc() into the callers Al Viro
2020-10-04 2:39 ` [RFC PATCH 16/27] lift the calls of ep_send_events_proc() " Al Viro
2020-10-04 2:39 ` [RFC PATCH 17/27] ep_send_events_proc(): fold into the caller Al Viro
2020-10-04 2:39 ` [RFC PATCH 18/27] lift locking/unlocking ep->mtx out of ep_{start,done}_scan() Al Viro
2020-10-04 2:39 ` Al Viro [this message]
2020-10-04 2:39 ` [RFC PATCH 20/27] ep_insert(): we only need tep->mtx around the insertion itself Al Viro
2020-10-04 12:56 ` [ep_insert()] 9ee1cc5666: WARNING:possible_recursive_locking_detected kernel test robot
2020-10-04 14:17 ` Al Viro
2020-10-04 14:27 ` Al Viro
2020-10-04 2:39 ` [RFC PATCH 21/27] take the common part of ep_eventpoll_poll() and ep_item_poll() into helper Al Viro
2020-10-04 2:39 ` [RFC PATCH 22/27] fold ep_read_events_proc() into the only caller Al Viro
2020-10-04 2:39 ` [RFC PATCH 23/27] ep_insert(): move creation of wakeup source past the fl_ep_links insertion Al Viro
2020-10-04 2:39 ` [RFC PATCH 24/27] convert ->f_ep_links/->fllink to hlist Al Viro
2020-10-04 2:39 ` [RFC PATCH 25/27] lift rcu_read_lock() into reverse_path_check() Al Viro
2020-10-04 2:39 ` [RFC PATCH 26/27] epoll: massage the check list insertion Al Viro
2020-10-04 2:39 ` [RFC PATCH 27/27] epoll: take epitem list out of struct file Al Viro
2020-10-05 20:37 ` Qian Cai
2020-10-05 20:49 ` Al Viro
2020-10-04 2:49 ` [RFC][PATCHSET] epoll cleanups Al Viro
2020-10-04 12:13 ` Matthew Wilcox
2020-10-04 14:15 ` Al Viro
2020-10-04 18:08 ` Linus Torvalds
2020-10-04 20:05 ` Al Viro
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