path: root/drivers/usb/dwc3
diff options
authorStephen Warren <swarren@nvidia.com>2013-05-07 16:53:52 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-16 17:30:52 -0700
commit3b9561e9d9b88eca9d4ed6aab025dec2eeeed501 (patch)
tree6ac9d662f3b7c4ee4411d4fc5103f1226430740a /drivers/usb/dwc3
parent8ff10bdb14a52e3f25d4ce09e0582a8684c1a6db (diff)
USB: set device dma_mask without reference to global data
Many USB host drivers contain code such as: if (!pdev->dev.dma_mask) pdev->dev.dma_mask = &tegra_ehci_dma_mask; ... where tegra_ehci_dma_mask is a global. I suspect this code originated in commit 4a53f4e "USB: ehci-tegra: add probing through device tree" and was simply copied everywhere else. This works fine when the code is built-in, but can cause a crash when the code is in a module. The first module load sets up the dma_mask pointer, but if the module is removed and re-inserted, the value is now non-NULL, and hence is not updated to point at the new location, and hence points at a stale location within the previous module load address, which in turn causes a crash if the pointer is de-referenced. The simplest way of solving this seems to be to copy the code from ehci-platform.c, which uses the coherent_dma_mask as the target for the dma_mask pointer. Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Stephen Warren <swarren@nvidia.com> Acked-by: Tony Prisk <linux@prisktech.co.nz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/dwc3')
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
index a8afe6e26621..929e7dd6e58b 100644
--- a/drivers/usb/dwc3/dwc3-exynos.c
+++ b/drivers/usb/dwc3/dwc3-exynos.c
@@ -95,8 +95,6 @@ static int dwc3_exynos_remove_child(struct device *dev, void *unused)
return 0;
-static u64 dwc3_exynos_dma_mask = DMA_BIT_MASK(32);
static int dwc3_exynos_probe(struct platform_device *pdev)
struct dwc3_exynos *exynos;
@@ -118,7 +116,9 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
* Once we move to full device tree support this will vanish off.
if (!dev->dma_mask)
- dev->dma_mask = &dwc3_exynos_dma_mask;
+ dev->dma_mask = &dev->coherent_dma_mask;
+ if (!dev->coherent_dma_mask)
+ dev->coherent_dma_mask = DMA_BIT_MASK(32);
platform_set_drvdata(pdev, exynos);