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| author | Hans de Goede <hdegoede@redhat.com> | 2012-09-09 13:30:02 +0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2012-09-14 00:42:17 +0400 |
| commit | 345321dc9c52b774f42c934339f9b3e2f0a39395 (patch) | |
| tree | a86e8fde0d50634c467c0c9d75b37776037e27d7 /drivers/media/usb/gspca/xirlink_cit.c | |
| parent | 8c96f0a207bedb6f06089fde9adc7abe8136a087 (diff) | |
| download | linux-345321dc9c52b774f42c934339f9b3e2f0a39395.tar.xz | |
[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>
Diffstat (limited to 'drivers/media/usb/gspca/xirlink_cit.c')
| -rw-r--r-- | drivers/media/usb/gspca/xirlink_cit.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/drivers/media/usb/gspca/xirlink_cit.c b/drivers/media/usb/gspca/xirlink_cit.c index 13b8d395d210..d4b23c9bf90c 100644 --- a/drivers/media/usb/gspca/xirlink_cit.c +++ b/drivers/media/usb/gspca/xirlink_cit.c @@ -2697,9 +2697,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev) { struct sd *sd = (struct sd *) gspca_dev; - /* We cannot use gspca_dev->present here as that is not set when - sd_init gets called and we get called from sd_init */ - if (!gspca_dev->dev) + if (!gspca_dev->present) return; switch (sd->model) { |