[media] vpif_display: protect dma_queue by a spin_lock

The dma_queue list is accessed by both the interrupt handler and by normal
code. It needs to be protected by a lock to prevent possible list corruption.
Corruption has been observed in 'real-life' conditions. Adding this lock made
it go away.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/drivers/media/platform/davinci/vpif_display.c b/drivers/media/platform/davinci/vpif_display.c
index e5109ae0593d..9f2b603be9c9 100644
--- a/drivers/media/platform/davinci/vpif_display.c
+++ b/drivers/media/platform/davinci/vpif_display.c
@@ -177,11 +177,14 @@ static void vpif_buffer_queue(struct vb2_buffer *vb)
                                 struct vpif_disp_buffer, vb);
         struct channel_obj *ch = fh->channel;
         struct common_obj *common;
+        unsigned long flags;
 
         common = &ch->common[VPIF_VIDEO_INDEX];
 
         /* add the buffer to the DMA queue */
+        spin_lock_irqsave(&common->irqlock, flags);
         list_add_tail(&buf->list, &common->dma_queue);
+        spin_unlock_irqrestore(&common->irqlock, flags);
 }
 
 /*
@@ -246,10 +249,13 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
         struct common_obj *common = &ch->common[VPIF_VIDEO_INDEX];
         struct vpif_params *vpif = &ch->vpifparams;
         unsigned long addr = 0;
+        unsigned long flags;
         int ret;
 
         /* If buffer queue is empty, return error */
+        spin_lock_irqsave(&common->irqlock, flags);
         if (list_empty(&common->dma_queue)) {
+                spin_unlock_irqrestore(&common->irqlock, flags);
                 vpif_err("buffer queue is empty\n");
                 return -EIO;
         }
@@ -260,6 +266,7 @@ static int vpif_start_streaming(struct vb2_queue *vq, unsigned int count)
                                        struct vpif_disp_buffer, list);
 
         list_del(&common->cur_frm->list);
+        spin_unlock_irqrestore(&common->irqlock, flags);
         /* Mark state of the current frame to active */
         common->cur_frm->vb.state = VB2_BUF_STATE_ACTIVE;
 
@@ -330,6 +337,7 @@ static int vpif_stop_streaming(struct vb2_queue *vq)
         struct vpif_fh *fh = vb2_get_drv_priv(vq);
         struct channel_obj *ch = fh->channel;
         struct common_obj *common;
+        unsigned long flags;
 
         if (!vb2_is_streaming(vq))
                 return 0;
@@ -337,12 +345,14 @@ static int vpif_stop_streaming(struct vb2_queue *vq)
         common = &ch->common[VPIF_VIDEO_INDEX];
 
         /* release all active buffers */
+        spin_lock_irqsave(&common->irqlock, flags);
         while (!list_empty(&common->dma_queue)) {
                 common->next_frm = list_entry(common->dma_queue.next,
                                                 struct vpif_disp_buffer, list);
                 list_del(&common->next_frm->list);
                 vb2_buffer_done(&common->next_frm->vb, VB2_BUF_STATE_ERROR);
         }
+        spin_unlock_irqrestore(&common->irqlock, flags);
 
         return 0;
 }
@@ -363,11 +373,13 @@ static void process_progressive_mode(struct common_obj *common)
 {
         unsigned long addr = 0;
 
+        spin_lock(&common->irqlock);
         /* Get the next buffer from buffer queue */
         common->next_frm = list_entry(common->dma_queue.next,
                                 struct vpif_disp_buffer, list);
         /* Remove that buffer from the buffer queue */
         list_del(&common->next_frm->list);
+        spin_unlock(&common->irqlock);
         /* Mark status of the buffer as active */
         common->next_frm->vb.state = VB2_BUF_STATE_ACTIVE;
 
@@ -398,16 +410,18 @@ static void process_interlaced_mode(int fid, struct common_obj *common)
                 common->cur_frm = common->next_frm;
 
         } else if (1 == fid) {  /* odd field */
+                spin_lock(&common->irqlock);
                 if (list_empty(&common->dma_queue)
                     || (common->cur_frm != common->next_frm)) {
+                        spin_unlock(&common->irqlock);
                         return;
                 }
+                spin_unlock(&common->irqlock);
                 /* one field is displayed configure the next
                  * frame if it is available else hold on current
                  * frame */
                 /* Get next from the buffer queue */
                 process_progressive_mode(common);
-
         }
 }
 
@@ -437,8 +451,12 @@ static irqreturn_t vpif_channel_isr(int irq, void *dev_id)
                         continue;
 
                 if (1 == ch->vpifparams.std_info.frm_fmt) {
-                        if (list_empty(&common->dma_queue))
+                        spin_lock(&common->irqlock);
+                        if (list_empty(&common->dma_queue)) {
+                                spin_unlock(&common->irqlock);
                                 continue;
+                        }
+                        spin_unlock(&common->irqlock);
 
                         /* Progressive mode */
                         if (!channel_first_int[i][channel_id]) {