From: Roman Penyaev <rpenyaev@suse.de>
To: unlisted-recipients:; (no To-header on input)
Cc: Roman Penyaev <rpenyaev@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v5 09/14] epoll: support polling from userspace for ep_remove()
Date: Mon, 24 Jun 2019 16:41:46 +0200 [thread overview]
Message-ID: <20190624144151.22688-10-rpenyaev@suse.de> (raw)
In-Reply-To: <20190624144151.22688-1-rpenyaev@suse.de>
On ep_remove() simply mark a user item with EPOLLREMOVE if the item was
ready (i.e. has some bits set). That will prevent further user index
entry creation on item ->bit reuse.
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
fs/eventpoll.c | 34 ++++++++++++++++++++++++++++------
1 file changed, 28 insertions(+), 6 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index d0c057b73ea1..df96569d3b5a 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -900,12 +900,30 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep,
return res;
}
-static void epi_rcu_free(struct rcu_head *head)
+static void epi_rcu_free_cb(struct rcu_head *head)
{
struct epitem *epi = container_of(head, struct epitem, rcu);
kmem_cache_free(epi_cache, epi);
}
+static void uepi_rcu_free_cb(struct rcu_head *head)
+{
+ struct epitem *epi = container_of(head, struct epitem, rcu);
+ kmem_cache_free(uepi_cache, uep_item_from_epi(epi));
+}
+
+static void epi_rcu_free(struct eventpoll *ep, struct epitem *epi)
+{
+ /*
+ * Check if `ep` is polled by user here, in this function, not
+ * in the callback, in order not to control lifetime of the 'ep'.
+ */
+ if (ep_polled_by_user(ep))
+ call_rcu(&epi->rcu, uepi_rcu_free_cb);
+ else
+ call_rcu(&epi->rcu, epi_rcu_free_cb);
+}
+
static inline int ep_get_bit(struct eventpoll *ep)
{
bool was_set;
@@ -1177,10 +1195,14 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
rb_erase_cached(&epi->rbn, &ep->rbr);
- write_lock_irq(&ep->lock);
- if (ep_is_linked(epi))
- list_del_init(&epi->rdllink);
- write_unlock_irq(&ep->lock);
+ if (ep_polled_by_user(ep)) {
+ ep_remove_user_item(epi);
+ } else {
+ 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));
/*
@@ -1190,7 +1212,7 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
* ep->mtx. The rcu read side, reverse_path_check_proc(), does not make
* use of the rbn field.
*/
- call_rcu(&epi->rcu, epi_rcu_free);
+ epi_rcu_free(ep, epi);
atomic_long_dec(&ep->user->epoll_watches);
--
2.21.0
next prev parent reply other threads:[~2019-06-24 14:42 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 14:41 [PATCH v5 00/14] epoll: support pollable epoll from userspace Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 01/14] epoll: move private helpers from a header to the source Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 02/14] epoll: introduce user structures for polling from userspace Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 03/14] epoll: allocate user header and user events ring " Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 04/14] epoll: some sanity flags checks for epoll syscalls " Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 05/14] epoll: offload polling to a work in case of epfd polled " Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 06/14] epoll: introduce helpers for adding/removing events to uring Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 07/14] epoll: call ep_add_event_to_uring() from ep_poll_callback() Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 08/14] epoll: support polling from userspace for ep_insert() Roman Penyaev
2019-06-24 14:41 ` Roman Penyaev [this message]
2019-06-24 14:41 ` [PATCH v5 10/14] epoll: support polling from userspace for ep_modify() Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 11/14] epoll: support polling from userspace for ep_poll() Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 12/14] epoll: support mapping for epfd when polled from userspace Roman Penyaev
2019-06-24 14:41 ` [PATCH v5 13/14] epoll: implement epoll_create2() syscall Roman Penyaev
2019-06-24 16:14 ` Arnd Bergmann
2019-06-24 16:25 ` Roman Penyaev
2019-06-25 18:29 ` Eric Wong
2019-06-24 14:41 ` [PATCH v5 14/14] kselftest: add uepoll-test which tests polling from userspace Roman Penyaev
2019-06-24 20:38 ` [PATCH v5 00/14] epoll: support pollable epoll " Linus Torvalds
2019-06-25 11:19 ` Roman Penyaev
2019-06-25 0:24 ` Eric Wong
2019-06-25 11:07 ` Roman Penyaev
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