xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

USB: set device dma_mask without reference to global data

Browse Source 
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>
This commit is contained in:
Stephen Warren
2013-05-07 16:53:52 -06:00
committed by Greg Kroah-Hartman
parent 8ff10bdb14
commit 3b9561e9d9
14 changed files with 41 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/usb/dwc3/dwc3-exynos.c
View File

@@ -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);