media: vim2m: Remove unneeded buffer lock

This spinlock is used solely to call v4l2_m2m_buf_done().

Since buffers are obtained only after being removed
from the ready queue, there's no concurrent access, and
so no need for synchronization.

Remove the spinlock to make sure no one copies this pattern.

Some archaeology shows this is a small leftover from ancient code.
This driver (then called m2m_testdev) used the videobuf1 framework;
commit d80ee38c ("[media] v4l: mem2mem: port m2m_testdev to vb2")
converted it to videobuf2. The spinlock was then no longer needed,
and this simply went unnoticed.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/test_drivers/vim2m.c

@@ -216,7 +216,6 @@ struct vim2m_ctx {
 
 	struct mutex		vb_mutex;
 	struct delayed_work	work_run;
-	spinlock_t		irqlock;
 
 	/* Abort requested by m2m */
 	int			aborting;
@@ -622,7 +621,6 @@ static void device_work(struct work_struct *w)
 	struct vim2m_ctx *curr_ctx;
 	struct vim2m_dev *vim2m_dev;
 	struct vb2_v4l2_buffer *src_vb, *dst_vb;
-	unsigned long flags;
 
 	curr_ctx = container_of(w, struct vim2m_ctx, work_run.work);
 
@@ -638,10 +636,8 @@ static void device_work(struct work_struct *w)
 
 	curr_ctx->num_processed++;
 
-	spin_lock_irqsave(&curr_ctx->irqlock, flags);
 	v4l2_m2m_buf_done(src_vb, VB2_BUF_STATE_DONE);
 	v4l2_m2m_buf_done(dst_vb, VB2_BUF_STATE_DONE);
-	spin_unlock_irqrestore(&curr_ctx->irqlock, flags);
 
 	if (curr_ctx->num_processed == curr_ctx->translen
 	    || curr_ctx->aborting) {
@@ -1084,7 +1080,6 @@ static void vim2m_stop_streaming(struct vb2_queue *q)
 {
 	struct vim2m_ctx *ctx = vb2_get_drv_priv(q);
 	struct vb2_v4l2_buffer *vbuf;
-	unsigned long flags;
 
 	cancel_delayed_work_sync(&ctx->work_run);
 
@@ -1097,9 +1092,7 @@ static void vim2m_stop_streaming(struct vb2_queue *q)
 			return;
 		v4l2_ctrl_request_complete(vbuf->vb2_buf.req_obj.req,
 					   &ctx->hdl);
-		spin_lock_irqsave(&ctx->irqlock, flags);
 		v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR);
-		spin_unlock_irqrestore(&ctx->irqlock, flags);
 	}
 }
 
@@ -1226,7 +1219,6 @@ static int vim2m_open(struct file *file)
 	ctx->fh.m2m_ctx = v4l2_m2m_ctx_init(dev->m2m_dev, ctx, &queue_init);
 
 	mutex_init(&ctx->vb_mutex);
-	spin_lock_init(&ctx->irqlock);
 	INIT_DELAYED_WORK(&ctx->work_run, device_work);
 
 	if (IS_ERR(ctx->fh.m2m_ctx)) {