linux-kernel - [PATCH v3 3/4] staging: vchiq: make wait events interruptible

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Message-Id: <20190509143137.31254-4-nsaenzjulienne@suse.de>
Date:   Thu,  9 May 2019 16:31:35 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     linux-kernel@...r.kernel.org
Cc:     dan.carpenter@...cle.com, stefan.wahren@...e.com,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Eric Anholt <eric@...olt.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, devel@...verdev.osuosl.org
Subject: [PATCH v3 3/4] staging: vchiq: make wait events interruptible

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

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
index c65cf1e6f910..44bfa890e0e5 100644
--- 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 *wq, struct remote_event *event)
 	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;
 		}
-- 
2.21.0