[ 12/22] USB: UHCI: fix IRQ race during initialization

Greg Kroah-Hartman
2013-01-24T21:26:02Z

From: Alan Stern <stern@rowland.harvard.edu>

commit 0f815a0a700bc10547449bde6c106051a035a1b9 upstream.

This patch (as1644) fixes a race that occurs during startup in
uhci-hcd. If the IRQ line is shared with other devices, it's possible
for the handler routine to be called before the data structures are
fully initialized.

The problem is fixed by adding a check to the IRQ handler routine. If
the initialization hasn't finished yet, the routine will return
immediately.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Don Zickus <dzickus@redhat.com>
Tested-by: "Huang, Adrian (ISS Linux TW)" <adrian.huang@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/uhci-hcd.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -447,6 +447,10 @@ static irqreturn_t uhci_irq(struct usb_h
return IRQ_NONE;
uhci_writew(uhci, status, USBSTS); /* Clear it */

+ spin_lock(&uhci->lock);
+ if (unlikely(!uhci->is_initialized)) /* not yet configured */
+ goto done;
+
if (status & ~(USBSTS_USBINT | USBSTS_ERROR | USBSTS_RD)) {
if (status & USBSTS_HSE)
dev_err(uhci_dev(uhci), "host system error, "
@@ -455,7 +459,6 @@ static irqreturn_t uhci_irq(struct usb_h
dev_err(uhci_dev(uhci), "host controller process "
"error, something bad happened!\n");
if (status & USBSTS_HCH) {
- spin_lock(&uhci->lock);
if (uhci->rh_state >= UHCI_RH_RUNNING) {
dev_err(uhci_dev(uhci),
"host controller halted, "
@@ -473,15 +476,15 @@ static irqreturn_t uhci_irq(struct usb_h
* pending unlinks */
mod_timer(&hcd->rh_timer, jiffies);
}
- spin_unlock(&uhci->lock);
}
}

- if (status & USBSTS_RD)
+ if (status & USBSTS_RD) {
+ spin_unlock(&uhci->lock);
usb_hcd_poll_rh_status(hcd);
- else {
- spin_lock(&uhci->lock);
+ } else {
uhci_scan_schedule(uhci);
+ done:
spin_unlock(&uhci->lock);
}

@@ -662,9 +665,9 @@ static int uhci_start(struct usb_hcd *hc
*/
mb();

+ spin_lock_irq(&uhci->lock);
configure_hc(uhci);
uhci->is_initialized = 1;
- spin_lock_irq(&uhci->lock);
start_rh(uhci);
spin_unlock_irq(&uhci->lock);
return 0;