[PATCH, RFC 08/30] [media] arv: fix sleep_on race

From: Arnd Bergmann
Date: Thu Jan 02 2014 - 07:08:33 EST

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@xxxxxxxx>
Cc: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Cc: linux-media@xxxxxxxxxxxxxxx
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);
/* .... 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;

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