[media] media: am437x-vpfe: Fix a race condition during release

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")
Cc: <stable@vger.kernel.org> # v4.0+
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>

diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
index 1fed7a56c8ae47002170bb29f949d0fafc0631e9..c8447fa3fd91b4051ef7f47e03cb854d9f239028 100644 (file)
--- 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 vpfe_device *vpfe)
 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;