[media] gspca: Don't set gspca_dev->dev to NULL before stop0
In commit a3d6e8cc0e6ddc8b3cfdeb3c979f07ed1aa528b3 gspca_dev->dev is set
to NULL on disconnect, before calling stop0. The plan was to get rid of
gspca_dev->present and instead simply check for gspca_dev->dev everywhere
where we were checking for present. This should be race free since all users
of gspca_dev->dev hold the usb_lock, or so I thought.
But I was wrong, drivers which use a work-queue + synchronous bulk transfers
to get the video data don't hold the usb_lock while doing so, their stop0
callbacks stop the workqueue, so they won't be using gspca_dev->dev anymore
after the stop0 call, but they might be dereferincing it before, so we should
not set gspca_dev->dev to NULL on disconnect before calling stop0.
This also means that the workqueue functions in these drivers cannot
use gspca_dev->dev to check if they need to stop because of disconnection,
so we will need to keep gspca_dev->present around, and set that to 0 on
disconnect, before calling stop0. Unfortunately as part of the plan to remove
gspca_dev->present, these workqueues where already moved over to checking
for gspca_dev->dev instead of gspca_dev->present as part of commit
254902b01d2acc6aced99ec17caa4c6cd890cdea, so this patch also reverts those
parts of that commit.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/usb/gspca/sq905c.c b/drivers/media/usb/gspca/sq905c.c
index 70fae69..784620c 100644
--- a/drivers/media/usb/gspca/sq905c.c
+++ b/drivers/media/usb/gspca/sq905c.c
@@ -150,7 +150,7 @@
goto quit_stream;
}
- while (gspca_dev->dev && gspca_dev->streaming) {
+ while (gspca_dev->present && gspca_dev->streaming) {
#ifdef CONFIG_PM
if (gspca_dev->frozen)
break;
@@ -173,7 +173,7 @@
packet_type = FIRST_PACKET;
gspca_frame_add(gspca_dev, packet_type,
buffer, FRAME_HEADER_LEN);
- while (bytes_left > 0 && gspca_dev->dev) {
+ while (bytes_left > 0 && gspca_dev->present) {
data_len = bytes_left > SQ905C_MAX_TRANSFER ?
SQ905C_MAX_TRANSFER : bytes_left;
ret = usb_bulk_msg(gspca_dev->dev,
@@ -195,7 +195,7 @@
}
}
quit_stream:
- if (gspca_dev->dev) {
+ if (gspca_dev->present) {
mutex_lock(&gspca_dev->usb_lock);
sq905c_command(gspca_dev, SQ905C_CLEAR, 0);
mutex_unlock(&gspca_dev->usb_lock);