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: <sta...@vger.kernel.org> # v4.0+
Signed-off-by: Benoit Parrot <bpar...@ti.com>
---
Changes since v3:
- fix review comment to protect v4l2_fh_is_singular_file()

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

diff --git a/drivers/media/platform/am437x/am437x-vpfe.c 
b/drivers/media/platform/am437x/am437x-vpfe.c
index a30cc2f7e4f1..5ab50c6babe2 100644
--- a/drivers/media/platform/am437x/am437x-vpfe.c
+++ b/drivers/media/platform/am437x/am437x-vpfe.c
@@ -1185,14 +1185,24 @@ 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;
-- 
1.8.5.1

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