USB: EHCI & UHCI: fix race between root-hub suspend and port resume
This patch (as1321) fixes a problem with EHCI and UHCI root-hub
suspends: If the suspend occurs while a port is trying to resume, the
resume doesn't finish and simply gets lost. When remote wakeup is
enabled, this is undesirable behavior.
The patch checks first to see if any port resumes are in progress, and
if they are then it fails the root-hub suspend with -EBUSY.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 2c6571c..c75d927 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -120,9 +120,26 @@
del_timer_sync(&ehci->watchdog);
del_timer_sync(&ehci->iaa_watchdog);
- port = HCS_N_PORTS (ehci->hcs_params);
spin_lock_irq (&ehci->lock);
+ /* Once the controller is stopped, port resumes that are already
+ * in progress won't complete. Hence if remote wakeup is enabled
+ * for the root hub and any ports are in the middle of a resume or
+ * remote wakeup, we must fail the suspend.
+ */
+ if (hcd->self.root_hub->do_remote_wakeup) {
+ port = HCS_N_PORTS(ehci->hcs_params);
+ while (port--) {
+ if (ehci->reset_done[port] != 0) {
+ spin_unlock_irq(&ehci->lock);
+ ehci_dbg(ehci, "suspend failed because "
+ "port %d is resuming\n",
+ port + 1);
+ return -EBUSY;
+ }
+ }
+ }
+
/* stop schedules, clean any completed work */
if (HC_IS_RUNNING(hcd->state)) {
ehci_quiesce (ehci);
@@ -138,6 +155,7 @@
*/
ehci->bus_suspended = 0;
ehci->owned_ports = 0;
+ port = HCS_N_PORTS(ehci->hcs_params);
while (port--) {
u32 __iomem *reg = &ehci->regs->port_status [port];
u32 t1 = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;