Re: [PATCH v2] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan()

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Jul 12, 2022 at 05:33:45PM +0300, Dan Carpenter wrote:
> The dma_request_channel() function doesn't return error pointers, it
> returns NULL.
> 
> Fixes: fff86dfbbf82 ("PCI: endpoint: Enable DMA tests for endpoints with DMA capabilities")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks, I squashed this into fff86dfbbf82 on my pci/ctrl/dwc-edma
branch.  I added a mention of Shunsuke's previous post of a similar
fix, but merged this one because it fixes both the RX and TX paths.

> ---
> v2: Clean up the first IS_ERR_OR_NULL() check as well
> 
>  drivers/pci/endpoint/functions/pci-epf-test.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 34aac220dd4c..36b1801a061b 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -211,7 +211,7 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
>  	dma_cap_zero(mask);
>  	dma_cap_set(DMA_SLAVE, mask);
>  	dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
> -	if (IS_ERR_OR_NULL(dma_chan)) {
> +	if (!dma_chan) {
>  		dev_info(dev, "Failed to get private DMA rx channel. Falling back to generic one\n");
>  		goto fail_back_tx;
>  	}
> @@ -221,7 +221,7 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
>  	filter.dma_mask = BIT(DMA_MEM_TO_DEV);
>  	dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
>  
> -	if (IS_ERR(dma_chan)) {
> +	if (!dma_chan) {
>  		dev_info(dev, "Failed to get private DMA tx channel. Falling back to generic one\n");
>  		goto fail_back_rx;
>  	}
> -- 
> 2.35.1
>