[PATCH 4/4] ALSA: compress: reject restarting an ACTIVE task via origin_seqno

[Peter Ujfalusi <peter.ujfalusi@linux.intel.com>]

snd_compr_task_start_prepare() only rejects tasks with
state >= SND_COMPRESS_TASK_STATE_FINISHED. Since the enum is
IDLE(0) < ACTIVE(1) < FINISHED(2), this accepts ACTIVE tasks and
rejects FINISHED ones, the opposite of what the origin_seqno
mechanism needs: origin_seqno is meant to let a caller reuse a
FINISHED task's buffers for a new job, not to restart a task that is
still queued with the driver.

The seqno lookup path in snd_compr_task_start() has its own explicit
"task->state != IDLE" guard, but the origin_seqno lookup path relies
solely on this function, so it can restart an ACTIVE task, causing
ops->task_start() to be called twice for the same task and
runtime->active_tasks to be incremented twice without a matching
finish/stop.

Accept IDLE and FINISHED, reject ACTIVE, on both entry paths.

Fixes: 04177158cf98 ("ALSA: compress_offload: introduce accel operation mode")
Cc: stable@vger.kernel.org
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
---
 sound/core/compress_offload.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index bf13fa0877dd..27bc490aa3ff 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -1154,7 +1154,9 @@ static int snd_compr_task_start_prepare(struct snd_compr_task_runtime *task,
 {
 	if (task == NULL)
 		return -EINVAL;
-	if (task->state >= SND_COMPRESS_TASK_STATE_FINISHED)
+	/* only an unqueued or already finished task may be (re)started */
+	if (task->state != SND_COMPRESS_TASK_STATE_IDLE &&
+	    task->state != SND_COMPRESS_TASK_STATE_FINISHED)
 		return -EBUSY;
 	if (utask->input_size > task->input->size)
 		return -EINVAL;
-- 
2.56.0