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>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/usb/host/ohci-omap3.c b/drivers/usb/host/ohci-omap3.c
index ddfc31427bc0..8663851c8d8e 100644
--- a/drivers/usb/host/ohci-omap3.c
+++ b/drivers/usb/host/ohci-omap3.c
@@ -114,8 +114,6 @@ static const struct hc_driver ohci_omap3_hc_driver = {
 
 /*-------------------------------------------------------------------------*/
 
-static u64 omap_ohci_dma_mask = DMA_BIT_MASK(32);
-
 /*
  * configure so an HC device and id are always provided
  * always called with process context; sleeping is OK
@@ -168,8 +166,10 @@ static int ohci_hcd_omap3_probe(struct platform_device *pdev)
 	 * Since shared usb code relies on it, set it here for now.
 	 * Once we have dma capability bindings this can go away.
 	 */
-	if (!pdev->dev.dma_mask)
-		pdev->dev.dma_mask = &omap_ohci_dma_mask;
+	if (!dev->dma_mask)
+		dev->dma_mask = &dev->coherent_dma_mask;
+	if (!dev->coherent_dma_mask)
+		dev->coherent_dma_mask = DMA_BIT_MASK(32);
 
 	hcd = usb_create_hcd(&ohci_omap3_hc_driver, dev,
 			dev_name(dev));