* [PATCH] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan()
@ 2022-07-08 8:41 Dan Carpenter
2022-07-11 5:50 ` Shunsuke Mie
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2022-07-08 8:41 UTC (permalink / raw)
To: Kishon Vijay Abraham I, Frank Li, dmaengine
Cc: Lorenzo Pieralisi, Krzysztof Wilczyński, Bjorn Helgaas,
Shunsuke Mie, Hou Zhiqiang, Li Chen, Manivannan Sadhasivam,
linux-pci, kernel-janitors
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>
---
It's surprising and unfortunate that dma_request_channel() returns NULL
while dma_request_chan_by_mask() returns error pointers. These days
static checkers will catch this so it's not as bad as it could be but
still not ideal.
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;
}
--
2.35.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan()
2022-07-08 8:41 [PATCH] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan() Dan Carpenter
@ 2022-07-11 5:50 ` Shunsuke Mie
2022-07-12 7:43 ` Dan Carpenter
0 siblings, 1 reply; 3+ messages in thread
From: Shunsuke Mie @ 2022-07-11 5:50 UTC (permalink / raw)
To: Dan Carpenter
Cc: Kishon Vijay Abraham I, Frank Li, dmaengine, Lorenzo Pieralisi,
Krzysztof Wilczyński, Bjorn Helgaas, Hou Zhiqiang, Li Chen,
Manivannan Sadhasivam, linux-pci, kernel-janitors
This patch changes for a tx dma channel. There is a similar problem for a
rx one too. The code doesn't cause an error, but it is likely better to
change to just NULL checking.
2022年7月8日(金) 17:41 Dan Carpenter <dan.carpenter@oracle.com>:
>
> 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>
> ---
> It's surprising and unfortunate that dma_request_channel() returns NULL
> while dma_request_chan_by_mask() returns error pointers. These days
> static checkers will catch this so it's not as bad as it could be but
> still not ideal.
>
> 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;
> }
> --
> 2.35.1
>
Thanks,
Shunsuke.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan()
2022-07-11 5:50 ` Shunsuke Mie
@ 2022-07-12 7:43 ` Dan Carpenter
0 siblings, 0 replies; 3+ messages in thread
From: Dan Carpenter @ 2022-07-12 7:43 UTC (permalink / raw)
To: Shunsuke Mie
Cc: Kishon Vijay Abraham I, Frank Li, dmaengine, Lorenzo Pieralisi,
Krzysztof Wilczyński, Bjorn Helgaas, Hou Zhiqiang, Li Chen,
Manivannan Sadhasivam, linux-pci, kernel-janitors
On Mon, Jul 11, 2022 at 02:50:14PM +0900, Shunsuke Mie wrote:
> This patch changes for a tx dma channel. There is a similar problem for a
> rx one too. The code doesn't cause an error, but it is likely better to
> change to just NULL checking.
>
Yep. Thanks. I will resend.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-07-08 8:41 [PATCH] PCI: endpoint: IS_ERR() vs NULL bug in pci_epf_test_init_dma_chan() Dan Carpenter
2022-07-11 5:50 ` Shunsuke Mie
2022-07-12 7:43 ` Dan Carpenter
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