linux-kernel - [PATCH 5.2 54/61] staging: vchiq: make wait events interruptible

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Message-Id: <20190712121623.644648361@linuxfoundation.org>
Date:   Fri, 12 Jul 2019 14:20:07 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Stefan Wahren <stefan.wahren@...e.com>
Subject: [PATCH 5.2 54/61] staging: vchiq: make wait events interruptible

From: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>

commit 77cf3f5dcf35c8f547f075213dbc15146d44cc76 upstream.

The killable version of wait_event() is meant to be used on situations
where it should not fail at all costs, but still have the convenience of
being able to kill it if really necessary. Wait events in VCHIQ doesn't
fit this criteria, as it's mainly used as an interface to V4L2 and ALSA
devices.

Fixes: 852b2876a8a8 ("staging: vchiq: rework remove_event handling")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Acked-by: Stefan Wahren <stefan.wahren@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
@@ -395,13 +395,21 @@ remote_event_create(wait_queue_head_t *w
 	init_waitqueue_head(wq);
 }
 
+/*
+ * All the event waiting routines in VCHIQ used a custom semaphore
+ * implementation that filtered most signals. This achieved a behaviour similar
+ * to the "killable" family of functions. While cleaning up this code all the
+ * routines where switched to the "interruptible" family of functions, as the
+ * former was deemed unjustified and the use "killable" set all VCHIQ's
+ * threads in D state.
+ */
 static inline int
 remote_event_wait(wait_queue_head_t *wq, struct remote_event *event)
 {
 	if (!event->fired) {
 		event->armed = 1;
 		dsb(sy);
-		if (wait_event_killable(*wq, event->fired)) {
+		if (wait_event_interruptible(*wq, event->fired)) {
 			event->armed = 0;
 			return 0;
 		}