[PATCH 1/6] media: airspy: Return queued buffers on start_streaming() failure

[Valery Borovsky]

The vb2 framework hands buffers to the driver via buf_queue() before
calling start_streaming().  If start_streaming() returns an error
without first returning those buffers via vb2_buffer_done(),
vb2_start_streaming() fires WARN_ON(owned_by_drv_count) and the queued
buffers leak.

airspy_start_streaming() returned -ENODEV early when the USB device had
been disconnected (s->udev == NULL) without returning any buffers that
buf_queue() had already accepted.  Take v4l2_lock first and jump to the
existing err_clear_bit label, which already drains s->queued_bufs via
vb2_buffer_done(..., VB2_BUF_STATE_QUEUED) before unlocking.

This mirrors the uvcvideo fix in commit 4cf3b6fd54eb ("media: uvcvideo:
Return queued buffers on start_streaming() failure").

Fixes: 634fe5033951 ("[media] airspy: AirSpy SDR driver")
Cc: stable at vger.kernel.org
Signed-off-by: Valery Borovsky <vebohr at gmail.com>
---
 drivers/media/usb/airspy/airspy.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/media/usb/airspy/airspy.c b/drivers/media/usb/airspy/airspy.c
index 8f6b721ba107..57edb42463e8 100644
--- a/drivers/media/usb/airspy/airspy.c
+++ b/drivers/media/usb/airspy/airspy.c
@@ -522,11 +522,13 @@ static int airspy_start_streaming(struct vb2_queue *vq, unsigned int count)
 
 	dev_dbg(s->dev, "\n");
 
-	if (!s->udev)
-		return -ENODEV;
-
 	mutex_lock(&s->v4l2_lock);
 
+	if (!s->udev) {
+		ret = -ENODEV;
+		goto err_clear_bit;
+	}
+
 	s->sequence = 0;
 
 	set_bit(POWER_ON, &s->flags);
-- 
2.51.0