[patch 11/47] USB: ehci - fix timer regression

Greg KH
2008-07-22T23:21:47Z

[-- Attachment #1: usb-ehci-fix-timer-regression.patch --]
[-- Type: text/plain, Size: 2135 bytes --]

2.6.25-stable review patch. If anyone has any objections, please let us
know.

------------------
From: David Brownell <david-b@pacbell.net>

commit 056761e55c8687ddf3db14226213f2e8dc2689bc upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/host/ehci.h | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -176,6 +176,15 @@ timer_action_done (struct ehci_hcd *ehci
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;

@@ -191,15 +200,7 @@ timer_action (struct ehci_hcd *ehci, enu
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);
}
}

--