Gitweb:     http://git.kernel.org/linus/980fd895e63a831bb8f0db8741a19169d9274c75
Commit:     980fd895e63a831bb8f0db8741a19169d9274c75
Parent:     f2eb5197740d5c1c85de8a96111f153c33c4891e
Author:     Julia Lawall <julia@diku.dk>
AuthorDate: Sun Jul 12 09:43:21 2009 +0200
Committer:  Greg Kroah-Hartman <gregkh@suse.de>
CommitDate: Tue Sep 15 12:01:40 2009 -0700

    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>
---
 drivers/staging/b3dfg/b3dfg.c |   41 +++++++++++++++++------------------------
 1 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/drivers/staging/b3dfg/b3dfg.c b/drivers/staging/b3dfg/b3dfg.c
index eec9c99..94c5d27 100644
--- 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;
--
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