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authorTakamasa Ohtake <ohtake-txa@necst.nec.co.jp>2006-12-07 04:04:15 +0300
committerGreg Kroah-Hartman <gregkh@suse.de>2006-12-20 21:14:27 +0300
commit23d10a9e376d6a9cd4afd4e27e5e403864f6729b (patch)
treeed13d347496c39fc25a0688385b83e1f0b17a302 /drivers/usb/host/ohci-hub.c
parentee269d98a9248fbb729c20ffda0f1b97e82c5c37 (diff)
downloadlinux-23d10a9e376d6a9cd4afd4e27e5e403864f6729b.tar.xz
USB: ohci handles hardware faults during root port resets
I have found a problem where the root_port_reset() goes into an infinite loop and stalls the kernel. This happens when a hardware fault inside the machine occurs during a small timing window. In case of USB device connection, if a USB device responds to hcd_submit_urb(), and later the controller fails before root_port_reset(), root_port_reset() will loop infinitely because ohci_readl() will always return "-1". Such a failure can include ejecting a CardBus OHCI controller. The probability of this problem is low, but it will increase if PnP type usage is frequent. The attached patch can solve this problem and I believe that it is better to fix this problem. Signed-off-by: Takamasa Ohtake <ohtake-txa@necst.nec.co.jp> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ohci-hub.c')
-rw-r--r--drivers/usb/host/ohci-hub.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index f9748b67e5e7..216c9c9d4d6d 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -555,7 +555,7 @@ static void start_hnp(struct ohci_hcd *ohci);
#define tick_before(t1,t2) ((s16)(((s16)(t1))-((s16)(t2))) < 0)
/* called from some task, normally khubd */
-static inline void root_port_reset (struct ohci_hcd *ohci, unsigned port)
+static inline int root_port_reset (struct ohci_hcd *ohci, unsigned port)
{
__hc32 __iomem *portstat = &ohci->regs->roothub.portstatus [port];
u32 temp;
@@ -570,6 +570,9 @@ static inline void root_port_reset (struct ohci_hcd *ohci, unsigned port)
/* spin until any current reset finishes */
for (;;) {
temp = ohci_readl (ohci, portstat);
+ /* handle e.g. CardBus eject */
+ if (temp == ~(u32)0)
+ return -ESHUTDOWN;
if (!(temp & RH_PS_PRS))
break;
udelay (500);
@@ -586,6 +589,8 @@ static inline void root_port_reset (struct ohci_hcd *ohci, unsigned port)
now = ohci_readl(ohci, &ohci->regs->fmnumber);
} while (tick_before(now, reset_done));
/* caller synchronizes using PRSC */
+
+ return 0;
}
static int ohci_hub_control (
@@ -702,7 +707,7 @@ static int ohci_hub_control (
&ohci->regs->roothub.portstatus [wIndex]);
break;
case USB_PORT_FEAT_RESET:
- root_port_reset (ohci, wIndex);
+ retval = root_port_reset (ohci, wIndex);
break;
default:
goto error;