linux-kernel - [PATCH, RFC 08/30] [media] arv: fix sleep

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Date:	Thu,  2 Jan 2014 13:07:32 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-kernel@...r.kernel.org
Cc:	Arnd Bergmann <arnd@...db.de>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	linux-media@...r.kernel.org
Subject: [PATCH, RFC 08/30] [media] arv: fix sleep_on race

interruptible_sleep_on is racy and going away. In the arv driver that
race has probably never caused problems since it would require a whole
video frame to be captured before the read function has a chance to
go to sleep, but using wait_event_interruptible lets us kill off the
old interface. In order to do this, we have to slightly adapt the
meaning of the ar->start_capture field to distinguish between not having
started a frame and having completed it.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Cc: Mauro Carvalho Chehab <m.chehab@...sung.com>
Cc: linux-media@...r.kernel.org
---
 drivers/media/platform/arv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/arv.c b/drivers/media/platform/arv.c
index e346d32d..32f6d70 100644
--- a/drivers/media/platform/arv.c
+++ b/drivers/media/platform/arv.c
@@ -307,11 +307,11 @@ static ssize_t ar_read(struct file *file, char *buf, size_t count, loff_t *ppos)
 	/*
 	 * Okay, kick AR LSI to invoke an interrupt
 	 */
-	ar->start_capture = 0;
+	ar->start_capture = -1;
 	ar_outl(arvcr1 | ARVCR1_HIEN, ARVCR1);
 	local_irq_restore(flags);
 	/* .... AR interrupts .... */
-	interruptible_sleep_on(&ar->wait);
+	wait_event_interruptible(ar->wait, ar->start_capture == 0);
 	if (signal_pending(current)) {
 		printk(KERN_ERR "arv: interrupted while get frame data.\n");
 		ret = -EINTR;
-- 
1.8.3.2

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