[PATCH] USB: Fix USB suspend/resume crasher (#2)

This patch closes the IRQ race and makes various other OHCI & EHCI code
path safer vs. suspend/resume.
I've been able to (finally !) successfully suspend and resume various
Mac models, with or without USB mouse plugged, or plugging while asleep,
or unplugging while asleep etc... all without a crash.

Alan, please verify the UHCI bit I did, I only verified that it builds.
It's very simple so I wouldn't expect any issue there. If you aren't
confident, then just drop the hunks that change uhci-hcd.c

I also made the patch a little bit more "safer" by making sure the store
to the interrupt register that disables interrupts is not posted before
I set the flag and drop the spinlock.

Without this patch, you cannot reliably sleep/wakeup any recent Mac, and
I suspect PCs have some more sneaky issues too (they don't frankly crash
with machine checks because x86 tend to silently swallow PCI errors but
that won't last afaik, at least PCI Express will blow up in those
situations, but the USB code may still misbehave).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index d33ce3982a5f..ed550132db0b 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -717,6 +717,7 @@ static int uhci_suspend(struct usb_hcd *hcd, pm_message_t message)
          * at the source, so we must turn off PIRQ.
          */
         pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP, 0);
+        clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
         uhci->hc_inaccessible = 1;
         hcd->poll_rh = 0;
 
@@ -733,6 +734,11 @@ static int uhci_resume(struct usb_hcd *hcd)
 
         dev_dbg(uhci_dev(uhci), "%s\n", __FUNCTION__);
 
+        /* We aren't in D3 state anymore, we do that even if dead as I
+         * really don't want to keep a stale HCD_FLAG_HW_ACCESSIBLE=0
+         */
+        set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
+
         if (uhci->rh_state == UHCI_RH_RESET)    /* Dead */
                 return 0;
         spin_lock_irq(&uhci->lock);