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authorStephen Warren <swarren@nvidia.com>2013-05-08 02:53:52 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-17 04:30:52 +0400
commit3b9561e9d9b88eca9d4ed6aab025dec2eeeed501 (patch)
tree6ac9d662f3b7c4ee4411d4fc5103f1226430740a /drivers/usb/host/ehci-atmel.c
parent8ff10bdb14a52e3f25d4ce09e0582a8684c1a6db (diff)
downloadlinux-3b9561e9d9b88eca9d4ed6aab025dec2eeeed501.tar.xz
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/host/ehci-atmel.c')
-rw-r--r--drivers/usb/host/ehci-atmel.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/usb/host/ehci-atmel.c b/drivers/usb/host/ehci-atmel.c
index 66420097c242..02f4611faa62 100644
--- a/drivers/usb/host/ehci-atmel.c
+++ b/drivers/usb/host/ehci-atmel.c
@@ -63,8 +63,6 @@ static void atmel_stop_ehci(struct platform_device *pdev)
/*-------------------------------------------------------------------------*/
-static u64 at91_ehci_dma_mask = DMA_BIT_MASK(32);
-
static int ehci_atmel_drv_probe(struct platform_device *pdev)
{
struct usb_hcd *hcd;
@@ -93,7 +91,9 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
* Once we have dma capability bindings this can go away.
*/
if (!pdev->dev.dma_mask)
- pdev->dev.dma_mask = &at91_ehci_dma_mask;
+ pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
+ if (!pdev->dev.coherent_dma_mask)
+ pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
if (!hcd) {