USB: ehci - fix timer regression

This patch fixes a regression in the EHCI driver's TIMER_IO_WATCHDOG
behavior.  The patch "USB: EHCI: add separate IAA watchdog timer" changed
how that timer is handled, so that short timeouts on the remaining
timer (unfortunately, overloaded) would never be used.

This takes a more direct approach, reorganizing the code slightly to
be explicit about only the I/O watchdog role now being overridable.
It also replaces a now-obsolete comment describing older timer behavior.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Leonid <leonidv11@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 9 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 35a03095757e..90245fd8bac4 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -177,6 +177,15 @@ timer_action_done (struct ehci_hcd *ehci, enum ehci_timer_action action)
 static inline void
 timer_action (struct ehci_hcd *ehci, enum ehci_timer_action action)
 {
+        /* Don't override timeouts which shrink or (later) disable
+         * the async ring; just the I/O watchdog.  Note that if a
+         * SHRINK were pending, OFF would never be requested.
+         */
+        if (timer_pending(&ehci->watchdog)
+                        && ((BIT(TIMER_ASYNC_SHRINK) | BIT(TIMER_ASYNC_OFF))
+                                & ehci->actions))
+                return;
+
         if (!test_and_set_bit (action, &ehci->actions)) {
                 unsigned long t;
 
@@ -192,15 +201,7 @@ timer_action (struct ehci_hcd *ehci, enum ehci_timer_action action)
                         t = EHCI_SHRINK_JIFFIES;
                         break;
                 }
-                t += jiffies;
-                // all timings except IAA watchdog can be overridden.
-                // async queue SHRINK often precedes IAA.  while it's ready
-                // to go OFF neither can matter, and afterwards the IO
-                // watchdog stops unless there's still periodic traffic.
-                if (time_before_eq(t, ehci->watchdog.expires)
-                                && timer_pending (&ehci->watchdog))
-                        return;
-                mod_timer (&ehci->watchdog, t);
+                mod_timer(&ehci->watchdog, t + jiffies);
         }
 }