linux-kernel - [PATCH v2] PCI: endpoint: functions/pci-epf-test: Avoid DMA release when DMA is unsupported

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Date:   Wed, 22 Apr 2020 16:24:47 +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,
        Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Subject: [PATCH v2] PCI: endpoint: functions/pci-epf-test: Avoid DMA release when DMA is unsupported

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, 3 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 60330f3e..c89a956 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -187,6 +187,9 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
  */
 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);
 	epf_test->dma_chan = NULL;
 }
-- 
2.7.4