[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>

diff --git a/drivers/media/platform/davinci/vpif_display.c b/drivers/media/platform/davinci/vpif_display.c
index e5109ae0593d7b93ed1a38ca19a3e226d696a5df..9f2b603be9c9b319d56b72bd99c3028df07632aa 100644 (file)
--- 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]) {