[PATCH v6 3/8] media: meson: vdec: Handle kthread failure and free codec state

[Anand Moon]

vdec_start_streaming() launches a recycle thread when required by the
codec. If kthread_run() fails, the previous error path only powered off
the hardware, leaving sess->priv and codec state allocated. This caused
a permanent leak of the codec context and associated DMA buffers.

Fix this by introducing a dedicated err_cleanup path:

- Call codec_ops->stop() to release the codec context and clear sess->priv.
- Power off the hardware before freeing buffers to avoid DMA faults.
- Free canvas IDs explicitly and set sess->vififo_vaddr = NULL after
  dma_free_coherent() to guard against double‑free in fallback stop paths.
- Reset core->cur_sess and sess->status to prevent stale references.

Following change closes the memory leak on kthread_run() failure and ensures
robust cleanup of codec resources in both error and stop paths.

Cc: Nicolas Dufresne <nicolas at ndufresne.ca>
Reported-by: Sashiko <sashiko-bot at kernel.org>
Closes: https://lore.kernel.org/all/20260521090944.F35401F00A3D@smtp.kernel.org/
Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
Signed-off-by: Anand Moon <linux.amoon at gmail.com>
---
 drivers/staging/media/meson/vdec/vdec.c | 26 ++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index 7233000e2232..8a5bf1a96830 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -32,6 +32,8 @@ struct dummy_buf {
 /* 16 MiB for parsed bitstream swap exchange */
 #define SIZE_VIFIFO SZ_16M
 
+static void vdec_free_canvas(struct amvdec_session *sess);
+
 static u32 get_output_size(u32 width, u32 height)
 {
 	return ALIGN(width * height, SZ_64K);
@@ -352,16 +354,31 @@ static int vdec_start_streaming(struct vb2_queue *q, unsigned int count)
 
 	sess->sequence_cap = 0;
 	sess->sequence_out = 0;
-	if (vdec_codec_needs_recycle(sess))
+	if (vdec_codec_needs_recycle(sess)) {
 		sess->recycle_thread = kthread_run(vdec_recycle_thread, sess,
 						   "vdec_recycle");
+		if (IS_ERR(sess->recycle_thread)) {
+			ret = PTR_ERR(sess->recycle_thread);
+			sess->recycle_thread = NULL;
+			goto err_cleanup;
+		}
+	}
 
 	schedule_work(&sess->esparser_queue_work);
 	return 0;
 
+err_cleanup:
+	vdec_free_canvas(sess);
+	vdec_poweroff(sess);
+	if (codec_ops && codec_ops->stop && sess->priv) {
+		codec_ops->stop(sess);
+		kfree(sess->priv);
+		sess->priv = NULL;
+	}
 vififo_free:
 	dma_free_coherent(sess->core->dev, sess->vififo_size,
 			  sess->vififo_vaddr, sess->vififo_paddr);
+	sess->vififo_vaddr = NULL;
 bufs_done:
 	mutex_lock(&core->lock);
 	if (core->cur_sess == sess)
@@ -441,8 +458,11 @@ static void vdec_stop_streaming(struct vb2_queue *q)
 
 		vdec_poweroff(sess);
 		vdec_free_canvas(sess);
-		dma_free_coherent(sess->core->dev, sess->vififo_size,
-				  sess->vififo_vaddr, sess->vififo_paddr);
+		if (sess->vififo_vaddr) {
+			dma_free_coherent(sess->core->dev, sess->vififo_size,
+					  sess->vififo_vaddr,
+					  sess->vififo_paddr);
+		}
 		vdec_reset_timestamps(sess);
 		vdec_reset_bufs_recycle(sess);
 		kfree(sess->priv);
-- 
2.50.1