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USB: set device dma_mask without reference to global data

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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
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4
drivers/usb/host/ohci-exynos.c
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@@ -98,8 +98,6 @@ static const struct hc_driver exynos_ohci_hc_driver = {
.start_port_reset = ohci_start_port_reset,
};
static u64 ohci_exynos_dma_mask = DMA_BIT_MASK(32);
static int exynos_ohci_probe(struct platform_device *pdev)
{
struct exynos4_ohci_platdata *pdata = pdev->dev.platform_data;
@@ -117,7 +115,7 @@ static int exynos_ohci_probe(struct platform_device *pdev)
* Once we move to full device tree support this will vanish off.
*/
if (!pdev->dev.dma_mask)
pdev->dev.dma_mask = &ohci_exynos_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);