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 02/27] epoll: get rid of epitem->nwait
Date: Sun, 4 Oct 2020 03:39:04 +0100 [thread overview]
Message-ID: <20201004023929.2740074-2-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>
we use it only to indicate allocation failures within queueing
callback back to ep_insert(). Might as well use epq.epi for that
reporting...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/eventpoll.c | 46 ++++++++++++++++++++--------------------------
1 file changed, 20 insertions(+), 26 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index ae41868d9b35..44aca681d897 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -172,9 +172,6 @@ struct epitem {
/* The file descriptor information this item refers to */
struct epoll_filefd ffd;
- /* Number of active wait queue attached to poll operations */
- int nwait;
-
/* List containing poll wait queues */
struct eppoll_entry *pwqlist;
@@ -351,12 +348,6 @@ static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p)
return container_of(p, struct eppoll_entry, wait)->base;
}
-/* Get the "struct epitem" from an epoll queue wrapper */
-static inline struct epitem *ep_item_from_epqueue(poll_table *p)
-{
- return container_of(p, struct ep_pqueue, pt)->epi;
-}
-
/* Initialize the poll safe wake up structure */
static void ep_nested_calls_init(struct nested_calls *ncalls)
{
@@ -1307,24 +1298,28 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v
static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
poll_table *pt)
{
- struct epitem *epi = ep_item_from_epqueue(pt);
+ struct ep_pqueue *epq = container_of(pt, struct ep_pqueue, pt);
+ struct epitem *epi = epq->epi;
struct eppoll_entry *pwq;
- if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
- init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
- pwq->whead = whead;
- pwq->base = epi;
- if (epi->event.events & EPOLLEXCLUSIVE)
- add_wait_queue_exclusive(whead, &pwq->wait);
- else
- add_wait_queue(whead, &pwq->wait);
- pwq->next = epi->pwqlist;
- epi->pwqlist = pwq;
- epi->nwait++;
- } else {
- /* We have to signal that an error occurred */
- epi->nwait = -1;
+ if (unlikely(!epi)) // an earlier allocation has failed
+ return;
+
+ pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL);
+ if (unlikely(!pwq)) {
+ epq->epi = NULL;
+ return;
}
+
+ init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
+ pwq->whead = whead;
+ pwq->base = epi;
+ if (epi->event.events & EPOLLEXCLUSIVE)
+ add_wait_queue_exclusive(whead, &pwq->wait);
+ else
+ add_wait_queue(whead, &pwq->wait);
+ pwq->next = epi->pwqlist;
+ epi->pwqlist = pwq;
}
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
@@ -1510,7 +1505,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
epi->ep = ep;
ep_set_ffd(&epi->ffd, tfile, fd);
epi->event = *event;
- epi->nwait = 0;
epi->next = EP_UNACTIVE_PTR;
if (epi->event.events & EPOLLWAKEUP) {
error = ep_create_wakeup_source(epi);
@@ -1555,7 +1549,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
* high memory pressure.
*/
error = -ENOMEM;
- if (epi->nwait < 0)
+ if (!epq.epi)
goto error_unregister;
/* We have to drop the new item inside our item list to keep track of it */
--
2.11.0
next prev parent reply other threads:[~2020-10-04 2:41 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 ` Al Viro [this message]
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 ` [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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