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 23/27] ep_insert(): move creation of wakeup source past the fl_ep_links insertion
Date: Sun, 4 Oct 2020 03:39:25 +0100 [thread overview]
Message-ID: <20201004023929.2740074-23-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>
That's the beginning of preparations for taking f_ep_links out of struct file.
If insertion might fail, we will need a new failure exit. Having wakeup
source creation done after that point will simplify life there; ep_remove()
can (and commonly does) live with NULL epi->ws, so it can be used for
cleanup after ep_create_wakeup_source() failure. It can't be used before
the rbtree insertion, though, so if we are to unify all old failure exits,
we need to move that thing down. Then we would be free to do simple
kmem_cache_free() on the failure to insert into f_ep_links - no wakeup source
to leak on that failure exit.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/eventpoll.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1efe8a1a022a..66da645d5eb4 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1356,26 +1356,16 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
user_watches = atomic_long_read(&ep->user->epoll_watches);
if (unlikely(user_watches >= max_user_watches))
return -ENOSPC;
- if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
+ if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL)))
return -ENOMEM;
/* Item initialization follow here ... */
INIT_LIST_HEAD(&epi->rdllink);
INIT_LIST_HEAD(&epi->fllink);
- epi->pwqlist = NULL;
epi->ep = ep;
ep_set_ffd(&epi->ffd, tfile, fd);
epi->event = *event;
epi->next = EP_UNACTIVE_PTR;
- if (epi->event.events & EPOLLWAKEUP) {
- error = ep_create_wakeup_source(epi);
- if (error) {
- kmem_cache_free(epi_cache, epi);
- return error;
- }
- } else {
- RCU_INIT_POINTER(epi->ws, NULL);
- }
atomic_long_inc(&ep->user->epoll_watches);
@@ -1400,6 +1390,14 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
return -EINVAL;
}
+ if (epi->event.events & EPOLLWAKEUP) {
+ error = ep_create_wakeup_source(epi);
+ if (error) {
+ ep_remove(ep, epi);
+ return error;
+ }
+ }
+
/* Initialize the poll table using the queue callback */
epq.epi = epi;
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
--
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 ` [RFC PATCH 19/27] ep_insert(): don't open-code ep_remove() on failure exits Al Viro
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 ` Al Viro [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201004023929.2740074-23-viro@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).