[PATCH] PCI: endpoint: Fix a NULL vs IS_ERR() check in pci_epf_test_init_dma_chan()

[PATCH] PCI: endpoint: Fix a NULL vs IS_ERR() check in pci_epf_test_init_dma_chan()

[Peng Wu]

On failure, dma_request_channel() returns NULL and not a
ERR_PTR() value. Fix return value checking by using is NULL.

Signed-off-by: Peng Wu <wupeng58@huawei.com>
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 34aac220dd4c..eed6638ab71d 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -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;
 	}
-- 
2.17.1

Re: [PATCH] PCI: endpoint: Fix a NULL vs IS_ERR() check in pci_epf_test_init_dma_chan()

[Bjorn Helgaas]

[+cc Dan, Shunsuke]

On Thu, Jul 07, 2022 at 01:12:15PM +0000, Peng Wu wrote:
> On failure, dma_request_channel() returns NULL and not a
> ERR_PTR() value. Fix return value checking by using is NULL.
> 
> Signed-off-by: Peng Wu <wupeng58@huawei.com>

Thanks for the patch.  Dan posted the same thing later [1].

I'd be happy to do this, but Shunsuke suggested that the rx path
should be changed similarly, so I'll look for a patch that does both.

[1] https://lore.kernel.org/r/YsftwaVowtU9/pgn@kili
[2] https://lore.kernel.org/r/CANXvt5rK98-cEMgpzopY9POOK8a5=VDib8uKPLgJakOG=hRfwQ@mail.gmail.com

> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 34aac220dd4c..eed6638ab71d 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -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;
>  	}
> -- 
> 2.17.1
>