Hello Rongjun Ying,
The patch ca21a146a45a: "dmaengine: add CSR SiRFprimaII DMAC driver"
from Oct 27, 2011, leads to the following static checker warning:
drivers/dma/sirf-dma.c:754 sirfsoc_dma_prep_interleaved()
warn: passing zero to 'ERR_PTR'
drivers/dma/sirf-dma.c
689 static struct dma_async_tx_descriptor *sirfsoc_dma_prep_interleaved(
690 struct dma_chan *chan, struct dma_interleaved_template *xt,
691 unsigned long flags)
692 {
693 struct sirfsoc_dma *sdma = dma_chan_to_sirfsoc_dma(chan);
694 struct sirfsoc_dma_chan *schan = dma_chan_to_sirfsoc_dma_chan(chan);
695 struct sirfsoc_dma_desc *sdesc = NULL;
696 unsigned long iflags;
697 int ret;
698
699 if ((xt->dir != DMA_MEM_TO_DEV) && (xt->dir != DMA_DEV_TO_MEM)) {
700 ret = -EINVAL;
^^^^^^^^^^^^^
Here ret is set to an error.
701 goto err_dir;
702 }
703
704 /* Get free descriptor */
705 spin_lock_irqsave(&schan->lock, iflags);
706 if (!list_empty(&schan->free)) {
707 sdesc = list_first_entry(&schan->free, struct sirfsoc_dma_desc,
708 node);
709 list_del(&sdesc->node);
710 }
711 spin_unlock_irqrestore(&schan->lock, iflags);
712
713 if (!sdesc) {
714 /* try to free completed descriptors */
715 sirfsoc_dma_process_completed(sdma);
716 ret = 0;
^^^^^^^
Here it looks like we're deliberately returning NULL. Which causes a
static checker warning, but is fine 15% of the time.
717 goto no_desc;
718 }
719
[ snip ]
748
749 return &sdesc->desc;
750 err_xfer:
751 spin_unlock_irqrestore(&schan->lock, iflags);
752 no_desc:
753 err_dir:
754 return ERR_PTR(ret);
^^^^^^^^^^^
My question is, it looks like this is called from deinterlace_issue_dma()
and dmaengine_prep_interleaved_dma() but neither expects an error
pointer so the will Oops if we return anything besides NULL.
755 }
regards,
dan carpenter
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