From: Damien Le Moal <dlemoal@kernel.org>
To: "Shin'ichiro Kawasaki" <shinichiro.kawasaki@wdc.com>,
linux-pci@vger.kernel.org,
"Manivannan Sadhasivam" <mani@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Kishon Vijay Abraham I" <kishon@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>, Frank Li <Frank.Li@nxp.com>,
Niklas Cassel <cassel@kernel.org>
Subject: Re: [PATCH] PCI: endpoint: pci-epf-test: NULL check dma channels before release
Date: Fri, 12 Sep 2025 16:31:36 +0900 [thread overview]
Message-ID: <94e8dbce-9e9a-4fe7-b33c-1d451c07eba6@kernel.org> (raw)
In-Reply-To: <20250912071140.649968-1-shinichiro.kawasaki@wdc.com>
On 9/12/25 16:11, Shin'ichiro Kawasaki wrote:
> When endpoint controller driver is immature, the fields dma_chan_tx and
> dma_chan_rx of the struct pci_epf_test could be NULL even after epf
> initialization. However, pci_epf_test_clean_dma_chan() assumes that they
> are always non-NULL valid values, and causes kernel panic when the
> fields are NULL. To avoid the kernel panic, NULL check the fields before
> release.
>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> ---
> drivers/pci/endpoint/functions/pci-epf-test.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index e091193bd8a8..1c29d5dd4382 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -301,15 +301,20 @@ static void pci_epf_test_clean_dma_chan(struct pci_epf_test *epf_test)
> if (!epf_test->dma_supported)
> return;
>
> - dma_release_channel(epf_test->dma_chan_tx);
> - if (epf_test->dma_chan_tx == epf_test->dma_chan_rx) {
> + if (epf_test->dma_chan_tx) {
> + dma_release_channel(epf_test->dma_chan_tx);
> + if (epf_test->dma_chan_tx == epf_test->dma_chan_rx) {
> + epf_test->dma_chan_tx = NULL;
> + epf_test->dma_chan_rx = NULL;
> + return;
> + }
> epf_test->dma_chan_tx = NULL;
> - epf_test->dma_chan_rx = NULL;
> - return;
> }
Can we simplify here ?
if (epf_test->dma_chan_tx) {
dma_release_channel(epf_test->dma_chan_tx);
epf_test->dma_chan_tx = NULL;
if (epf_test->dma_chan_tx == epf_test->dma_chan_rx) {
epf_test->dma_chan_rx = NULL;
return;
}
}
>
> - dma_release_channel(epf_test->dma_chan_rx);
> - epf_test->dma_chan_rx = NULL;
> + if (epf_test->dma_chan_rx) {
> + dma_release_channel(epf_test->dma_chan_rx);
> + epf_test->dma_chan_rx = NULL;
> + }
> }
>
> static void pci_epf_test_print_rate(struct pci_epf_test *epf_test,
--
Damien Le Moal
Western Digital Research
next prev parent reply other threads:[~2025-09-12 7:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-12 7:11 [PATCH] PCI: endpoint: pci-epf-test: NULL check dma channels before release Shin'ichiro Kawasaki
2025-09-12 7:31 ` Damien Le Moal [this message]
2025-09-12 9:59 ` Shinichiro Kawasaki
2025-09-12 10:38 ` Damien Le Moal
2025-09-12 10:38 ` Damien Le Moal
2025-09-12 16:58 ` Manivannan Sadhasivam
2025-09-13 5:34 ` Shinichiro Kawasaki
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