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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>,
	Davidlohr Bueso <dbueso@suse.de>, Jason Baron <jbaron@akamai.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrea Parri <andrea.parri@amarulasolutions.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH v2 10/13] epoll: support polling from userspace for ep_modify()
Date: Mon, 21 Jan 2019 21:14:53 +0100	[thread overview]
Message-ID: <20190121201456.28338-11-rpenyaev@suse.de> (raw)
In-Reply-To: <20190121201456.28338-1-rpenyaev@suse.de>

When epfd is polled from userspace and item is being modified:

1. Update user item with new pointer or poll flags.
2. Add event to user ring if needed.

Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 fs/eventpoll.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index b9f51f4b94e7..3c3721c315a7 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2058,6 +2058,8 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event,
 static int ep_modify(struct eventpoll *ep, struct epitem *epi,
 		     const struct epoll_event *event)
 {
+	struct epoll_uitem *uitem;
+	__poll_t revents;
 	int pwake = 0;
 	poll_table pt;
 
@@ -2072,6 +2074,13 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi,
 	 */
 	epi->event.events = event->events; /* need barrier below */
 	epi->event.data = event->data; /* protected by mtx */
+
+	/* Update user item, barrier is below */
+	if (ep_polled_by_user(ep)) {
+		uitem = &ep->user_header->items[epi->bit];
+		uitem->event = *event;
+	}
+
 	if (epi->event.events & EPOLLWAKEUP) {
 		if (!ep_has_wakeup_source(epi))
 			ep_create_wakeup_source(epi);
@@ -2105,12 +2114,19 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi,
 	 * If the item is "hot" and it is not registered inside the ready
 	 * list, push it inside.
 	 */
-	if (ep_item_poll(epi, &pt, 1)) {
+	revents = ep_item_poll(epi, &pt, 1);
+	if (revents) {
+		bool added = false;
+
 		write_lock_irq(&ep->lock);
-		if (!ep_is_linked(epi)) {
+		if (ep_polled_by_user(ep))
+			added = ep_add_event_to_uring(epi, revents);
+		else if (!ep_is_linked(epi)) {
 			list_add_tail(&epi->rdllink, &ep->rdllist);
 			ep_pm_stay_awake(epi);
-
+			added = true;
+		}
+		if (added) {
 			/* Notify waiting tasks that events are available */
 			if (waitqueue_active(&ep->wq))
 				wake_up(&ep->wq);
-- 
2.19.1


  parent reply	other threads:[~2019-01-21 20:16 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-21 20:14 [RFC PATCH v2 00/13] epoll: support pollable epoll from userspace Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 01/13] epoll: move private helpers from a header to the source Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 02/13] epoll: introduce user structures for polling from userspace Roman Penyaev
2019-01-21 21:34   ` Linus Torvalds
2019-01-22 11:46     ` Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 03/13] epoll: allocate user header and user events ring " Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 04/13] epoll: some sanity flags checks for epoll syscalls " Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 05/13] epoll: offload polling to a work in case of epfd polled " Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 06/13] epoll: introduce helpers for adding/removing events to uring Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 07/13] epoll: call ep_add_event_to_uring() from ep_poll_callback() Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 08/13] epoll: support polling from userspace for ep_insert() Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 09/13] epoll: support polling from userspace for ep_remove() Roman Penyaev
2019-01-21 20:14 ` Roman Penyaev [this message]
2019-01-21 20:14 ` [RFC PATCH v2 11/13] epoll: support polling from userspace for ep_poll() Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 12/13] epoll: support mapping for epfd when polled from userspace Roman Penyaev
2019-01-21 20:14 ` [RFC PATCH v2 13/13] epoll: implement epoll_create2() syscall Roman Penyaev

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