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USB: ohci handles hardware faults during root port resets

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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>
This commit is contained in:
Takamasa Ohtake 2006-12-06 17:04:15 -08:00 committed by Greg Kroah-Hartman
parent ee269d98a9
commit 23d10a9e37
1 changed files with 7 additions and 2 deletions
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9
drivers/usb/host/ohci-hub.c
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@ -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;