[PATCH 4.2 070/134] [media] media: am437x-vpfe: Fix a race condition during release

Greg Kroah-Hartman
2015-09-26T20:59:17Z

From: Benoit Parrot <bparrot@ti.com>

commit c99235fa3ef833c3c23926085f2bb68851c8460a upstream.

There was a race condition where during cleanup/release operation
on-going streaming would cause a kernel panic because the hardware
module was disabled prematurely with IRQ still pending.

Fixes: 417d2e507edc ("[media] media: platform: add VPFE capture driver support for AM437X")

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/platform/am437x/am437x-vpfe.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/media/platform/am437x/am437x-vpfe.c
+++ b/drivers/media/platform/am437x/am437x-vpfe.c
@@ -1186,14 +1186,24 @@ static int vpfe_initialize_device(struct
static int vpfe_release(struct file *file)
{
struct vpfe_device *vpfe = video_drvdata(file);
+ bool fh_singular;
int ret;

mutex_lock(&vpfe->lock);

- if (v4l2_fh_is_singular_file(file))
- vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
+ /* Save the singular status before we call the clean-up helper */
+ fh_singular = v4l2_fh_is_singular_file(file);
+
+ /* the release helper will cleanup any on-going streaming */
ret = _vb2_fop_release(file, NULL);

+ /*
+ * If this was the last open file.
+ * Then de-initialize hw module.
+ */
+ if (fh_singular)
+ vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
+
mutex_unlock(&vpfe->lock);

return ret;