linux-kernel - Re: [PATCH] PCI: endpoint: functions/pci-epf-test: Avoid DMA release when DMA is unsupported

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Date:   Wed, 22 Apr 2020 14:12:16 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: endpoint: functions/pci-epf-test: Avoid DMA release
 when DMA is unsupported

On 2020/03/23 18:45, Kunihiko Hayashi wrote:
> When unbinding pci_epf_test, pci_epf_test_clean_dma_chan() is called in
> pci_epf_test_unbind() even though epf_test->dma_supported is false.
> As a result, dma_release_channel() will occur null pointer access because
> dma_chan isn't set.
> 
> This avoids calling dma_release_channel() if epf_test->dma_supported
> is false.
> 
> Fixes: a1d105d4ab8e ("PCI: endpoint: functions/pci-epf-test: Add DMA support to transfer data")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> ---
>   drivers/pci/endpoint/functions/pci-epf-test.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 3b4cf7e..8b4f136 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -609,7 +609,8 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
>   	int bar;
>   
>   	cancel_delayed_work(&epf_test->cmd_handler);
> -	pci_epf_test_clean_dma_chan(epf_test);
> +	if (epf_test->dma_supported)
> +		pci_epf_test_clean_dma_chan(epf_test);
>   	pci_epc_stop(epc);
>   	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
>   		epf_bar = &epf->bar[bar];
> 

Gentle ping.
Are there any comments about that?

Thank you,

---
Best Regards
Kunihiko Hayashi