[PATCH v2 1/2] media: mediatek: vcodec: Return source buffer on NULL va in stateful decoder

[Fei Shao]

mtk_vdec_worker() peeks the source buffer with v4l2_m2m_next_src_buf().
If vb2_plane_vaddr() returns NULL because the buffer has no kernel
mapping, the worker finishes the m2m job with the buffer still at the
head of the ready list. v4l2_m2m_job_finish() then schedules the same
job again, which fails the same way, so the decoder never makes
progress.

Remove the buffer from the ready list so that the job is not scheduled
again, and return it with VB2_BUF_STATE_ERROR so that userspace gets it
back. Print the error before that, as the buffer must not be touched
once it is returned.

Fixes: 590577a4e525 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Decoder Driver")
Signed-off-by: Fei Shao <fshao at chromium.org>

---

(no changes since v1)

 .../mediatek/vcodec/decoder/mtk_vcodec_dec_stateful.c         | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateful.c b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateful.c
index aa9bdee7a96c..a4cbb7c76998 100644
--- a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateful.c
+++ b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_stateful.c
@@ -348,9 +348,11 @@ static void mtk_vdec_worker(struct work_struct *work)
 	buf.dma_addr = vb2_dma_contig_plane_dma_addr(&src_buf->vb2_buf, 0);
 	buf.size = (size_t)src_buf->vb2_buf.planes[0].bytesused;
 	if (!buf.va) {
-		v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
 		mtk_v4l2_vdec_err(ctx, "[%d] id=%d src_addr is NULL!!", ctx->id,
 				  src_buf->vb2_buf.index);
+		v4l2_m2m_src_buf_remove(ctx->m2m_ctx);
+		v4l2_m2m_buf_done(src_buf, VB2_BUF_STATE_ERROR);
+		v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
 		return;
 	}
 	mtk_v4l2_vdec_dbg(3, ctx, "[%d] Bitstream VA=%p DMA=%pad Size=%zx vb=%p",
-- 
2.56.0.257.gf7497c7d27-goog