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Subject[PATCH 3/3] drivers/usb/gadget: Drop NULL test on list_entry result
From: Julia Lawall <julia@diku.dk>

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>

---
drivers/usb/gadget/amd5536udc.c | 56 +++++++++-----------
1 files changed, 25 insertions(+), 31 deletions(-)

diff --git a/drivers/usb/gadget/amd5536udc.c b/drivers/usb/gadget/amd5536udc.c
index 826f3ad..85f7aa9 100644
--- a/drivers/usb/gadget/amd5536udc.c
+++ b/drivers/usb/gadget/amd5536udc.c
@@ -2379,40 +2379,34 @@ static irqreturn_t udc_data_in_isr(struct udc *dev, int ep_ix)
if (!ep->cancel_transfer && !list_empty(&ep->queue)) {
req = list_entry(ep->queue.next,
struct udc_request, queue);
- if (req) {
- /*
- * length bytes transfered
- * check dma done of last desc. in PPBDU mode
- */
- if (use_dma_ppb_du) {
- td = udc_get_last_dma_desc(req);
- if (td) {
- dma_done =
- AMD_GETBITS(td->status,
- UDC_DMA_IN_STS_BS);
- /* don't care DMA done */
- req->req.actual =
- req->req.length;
- }
- } else {
- /* assume all bytes transferred */
+ /*
+ * length bytes transfered
+ * check dma done of last desc. in PPBDU mode
+ */
+ if (use_dma_ppb_du) {
+ td = udc_get_last_dma_desc(req);
+ if (td) {
+ dma_done =
+ AMD_GETBITS(td->status,
+ UDC_DMA_IN_STS_BS);
+ /* don't care DMA done */
req->req.actual = req->req.length;
}
+ } else {
+ /* assume all bytes transferred */
+ req->req.actual = req->req.length;
+ }

- if (req->req.actual == req->req.length) {
- /* complete req */
- complete_req(ep, req, 0);
- req->dma_going = 0;
- /* further request available ? */
- if (list_empty(&ep->queue)) {
- /* disable interrupt */
- tmp = readl(
- &dev->regs->ep_irqmsk);
- tmp |= AMD_BIT(ep->num);
- writel(tmp,
- &dev->regs->ep_irqmsk);
- }
-
+ if (req->req.actual == req->req.length) {
+ /* complete req */
+ complete_req(ep, req, 0);
+ req->dma_going = 0;
+ /* further request available ? */
+ if (list_empty(&ep->queue)) {
+ /* disable interrupt */
+ tmp = readl(&dev->regs->ep_irqmsk);
+ tmp |= AMD_BIT(ep->num);
+ writel(tmp, &dev->regs->ep_irqmsk);
}
}
}

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