[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, 16 insertions, 8 deletions

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 5bb872c3496d..bf03ec0d8ee2 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -912,6 +912,7 @@ submit_async (
         int                     epnum;
         unsigned long           flags;
         struct ehci_qh          *qh = NULL;
+        int                     rc = 0;
 
         qtd = list_entry (qtd_list->next, struct ehci_qtd, qtd_list);
         epnum = ep->desc.bEndpointAddress;
@@ -926,21 +927,28 @@ submit_async (
 #endif
 
         spin_lock_irqsave (&ehci->lock, flags);
+        if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
+                               &ehci_to_hcd(ehci)->flags))) {
+                rc = -ESHUTDOWN;
+                goto done;
+        }
+
         qh = qh_append_tds (ehci, urb, qtd_list, epnum, &ep->hcpriv);
+        if (unlikely(qh == NULL)) {
+                rc = -ENOMEM;
+                goto done;
+        }
 
         /* Control/bulk operations through TTs don't need scheduling,
          * the HC and TT handle it when the TT has a buffer ready.
          */
-        if (likely (qh != NULL)) {
-                if (likely (qh->qh_state == QH_STATE_IDLE))
-                        qh_link_async (ehci, qh_get (qh));
-        }
+        if (likely (qh->qh_state == QH_STATE_IDLE))
+                qh_link_async (ehci, qh_get (qh));
+ done:
         spin_unlock_irqrestore (&ehci->lock, flags);
-        if (unlikely (qh == NULL)) {
+        if (unlikely (qh == NULL))
                 qtd_list_free (ehci, urb, qtd_list);
-                return -ENOMEM;
-        }
-        return 0;
+        return rc;
 }
 
 /*-------------------------------------------------------------------------*/