[PATCH v7 06/19] media: meson: vdec: Fix race condition by canceling work sync

[Anand Moon <linux.amoon@gmail.com>]

Synchronize work-queue states cleanly during streaming teardown and
close operations to eliminate asynchronous pipeline race conditions.

The esparser ISR can schedule work onto 'esparser_queue_work'. While
synchronize_irq() ensures the ISR itself finishes executing, it does
not prevent any already scheduled work items from running concurrently
during driver teardown. This causes a race condition during stream
stopping or file closing.

Remove the scheduling of esparser queue work during destination buffer
completion, as freeing the vififo is handled elsewhere. Add synchronous
cancellation of any pending work in vdec_stop_streaming and vdec_close
before synchronizing interrupts to prevent use-after-free and race
conditions.

Cc: Nicolas Dufresne <nicolas@ndufresne.ca>
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260521090944.F35401F00A3D@smtp.kernel.org/
Signed-off-by: Anand Moon <linux.amoon@gmail.com>
---
 drivers/staging/media/meson/vdec/vdec.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index 7689ffdb2e500..6fe9722577179 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -484,11 +484,15 @@ static void vdec_stop_streaming(struct vb2_queue *q)
 			}
 		}
 
+		mutex_unlock(&core->lock);
 		/* Synchronize and flush pending hardware interrupt service routines */
 		synchronize_irq(core->vdec_irq);
 		/* Ensure esparser ISR finishes executing */
 		synchronize_irq(core->esparser_irq);
 
+		cancel_work_sync(&sess->esparser_queue_work);
+		mutex_lock(&core->lock);
+
 		vdec_poweroff(sess);
 		vdec_free_canvas(sess);
 
@@ -999,6 +1003,8 @@ static int vdec_close(struct file *file)
 	/* Ensure esparser ISR finishes executing */
 	synchronize_irq(core->esparser_irq);
 
+	cancel_work_sync(&sess->esparser_queue_work);
+
 	if (!IS_ERR_OR_NULL(sess->recycle_thread)) {
 		kthread_stop(sess->recycle_thread);
 		sess->recycle_thread = NULL;
-- 
2.50.1