[PATCH] net: allow netif_carrier to be called safely from IRQ

From: Stephen Hemminger
Date: Fri Jul 22 2011 - 18:53:54 EST

As reported by Ben Greer and Froncois Romieu. The code path in
the netif_carrier code leads it to try and disable
a late workqueue to reenable it immediately
-> linkwatch_fire_event
-> linkwatch_schedule_work
-> cancel_delayed_work
-> del_timer_sync

If __cancel_delayed_work is used instead then there is no
problem of waiting for running linkwatch_event.

There is a race between linkwatch_event running re-scheduling
but it is harmless to schedule an extra scan of the linkwatch queue.

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>

--- a/net/core/link_watch.c 2011-07-22 15:25:31.027533604 -0700
+++ b/net/core/link_watch.c 2011-07-22 15:31:27.531520028 -0700
@@ -126,7 +126,7 @@ static void linkwatch_schedule_work(int

/* It's already running which is good enough. */
- if (!cancel_delayed_work(&linkwatch_work))
+ if (!__cancel_delayed_work(&linkwatch_work))

/* Otherwise we reschedule it again for immediate execution. */

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