Staging: b3dfg: Drop NULL test on list_entry result

list_entry, which is an alias for container_of, cannot return NULL, as
there is no way to add a NULL value to a doubly linked list.

A simplified version of the semantic match that findds this problem is as
follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r@
expression x,E;
statement S1,S2;
position p,p1;
@@

*x = list_entry@p(...)
... when != x = E
*if@p1 (x == NULL) S1 else S2
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/b3dfg/b3dfg.c b/drivers/staging/b3dfg/b3dfg.c
index eec9c99ffaa0f55fdce5e8492be331e4169004e3..94c5d27d24d7a58b7ea4de184234c47e7e1970dc 100644 (file)
--- a/drivers/staging/b3dfg/b3dfg.c
+++ b/drivers/staging/b3dfg/b3dfg.c
@@ -632,18 +632,15 @@ static void transfer_complete(struct b3dfg_dev *fgdev)
        fgdev->cur_dma_frame_addr = 0;
 
        buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
-       if (buf) {
-               dev_dbg(dev, "handle frame completion\n");
-               if (fgdev->cur_dma_frame_idx == B3DFG_FRAMES_PER_BUFFER - 1) {
-
-                       /* last frame of that triplet completed */
-                       dev_dbg(dev, "triplet completed\n");
-                       buf->state = B3DFG_BUFFER_POPULATED;
-                       list_del_init(&buf->list);
-                       wake_up_interruptible(&fgdev->buffer_waitqueue);
-               }
-       } else {
-               dev_err(dev, "got frame but no buffer!\n");
+
+       dev_dbg(dev, "handle frame completion\n");
+       if (fgdev->cur_dma_frame_idx == B3DFG_FRAMES_PER_BUFFER - 1) {
+
+               /* last frame of that triplet completed */
+               dev_dbg(dev, "triplet completed\n");
+               buf->state = B3DFG_BUFFER_POPULATED;
+               list_del_init(&buf->list);
+               wake_up_interruptible(&fgdev->buffer_waitqueue);
        }
 }
 
@@ -663,19 +660,15 @@ static bool setup_next_frame_transfer(struct b3dfg_dev *fgdev, int idx)
        dev_dbg(dev, "program DMA transfer for next frame: %d\n", idx);
 
        buf = list_entry(fgdev->buffer_queue.next, struct b3dfg_buffer, list);
-       if (buf) {
-               if (idx == fgdev->cur_dma_frame_idx + 2) {
-                       if (setup_frame_transfer(fgdev, buf, idx - 1))
-                               dev_err(dev, "unable to map DMA buffer\n");
-                       need_ack = 0;
-               } else {
-                       dev_err(dev, "frame mismatch, got %d, expected %d\n",
-                               idx, fgdev->cur_dma_frame_idx + 2);
-
-                       /* FIXME: handle dropped triplets here */
-               }
+       if (idx == fgdev->cur_dma_frame_idx + 2) {
+               if (setup_frame_transfer(fgdev, buf, idx - 1))
+                       dev_err(dev, "unable to map DMA buffer\n");
+               need_ack = 0;
        } else {
-               dev_err(dev, "cannot setup DMA, no buffer\n");
+               dev_err(dev, "frame mismatch, got %d, expected %d\n",
+                       idx, fgdev->cur_dma_frame_idx + 2);
+
+               /* FIXME: handle dropped triplets here */
        }
 
        return need_ack;