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Fix vcam streaming lifecycle correctness in videobuf #48

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Fix vcam streaming lifecycle correctness in videobuf #48

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72a5155
Use IS_ERR() for kthread_create() error handling
davidzwei Jun 2, 2026
10ead39
Move vb2_buffer_done() out of spinlock
davidzwei Jun 2, 2026
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18 changes: 11 additions & 7 deletions videobuf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -70,8 +70,9 @@ static int vcam_start_streaming(struct vb2_queue *q, unsigned int count)

/* Try to start kernel thread */
dev->sub_thr_id = kthread_create(submitter_thread, dev, "vcam_submitter");
if (!dev->sub_thr_id) {
if (IS_ERR(dev->sub_thr_id)) {
pr_err("Failed to create kernel thread\n");
dev->sub_thr_id = NULL;
return -ECANCELED;
}

Expand All @@ -85,22 +86,25 @@ static void vcam_stop_streaming(struct vb2_queue *vb2_q)
struct vcam_device *dev = vb2_q->drv_priv;
struct vcam_out_queue *q = &dev->vcam_out_vidq;
unsigned long flags = 0;
LIST_HEAD(tmp_list);

/* Stop running threads */
if (dev->sub_thr_id)
kthread_stop(dev->sub_thr_id);

dev->sub_thr_id = NULL;
/* Empty buffer queue */

/* Collect buffers under spinlock, return them to vb2 outside it.
* vb2_buffer_done() must not be called while holding a spinlock. */
spin_lock_irqsave(&dev->out_q_slock, flags);
while (!list_empty(&q->active)) {
list_splice_init(&q->active, &tmp_list);
spin_unlock_irqrestore(&dev->out_q_slock, flags);

while (!list_empty(&tmp_list)) {
struct vcam_out_buffer *buf =
list_entry(q->active.next, struct vcam_out_buffer, list);
list_entry(tmp_list.next, struct vcam_out_buffer, list);
list_del(&buf->list);
vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
pr_debug("Throwing out buffer\n");
}
spin_unlock_irqrestore(&dev->out_q_slock, flags);
}

static void vcam_outbuf_lock(struct vb2_queue *vq)
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