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>
diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
index a8afe6e..929e7dd 100644
--- a/drivers/usb/dwc3/dwc3-exynos.c
+++ b/drivers/usb/dwc3/dwc3-exynos.c
@@ -95,8 +95,6 @@
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 @@
* 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);