Messages in this thread | | | Subject | Re: [PATCH] Export current_is_keventd() for libphy | From | Roland Dreier <> | Date | Tue, 05 Dec 2006 13:37:37 -0800 |
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> a) Ban the calling of flush_scheduled_work() from under rtnl_lock(). > Sounds hard.
Unfortunate if this is happening a lot. It seems like the most sensible fix -- flush_scheduled_work() is in effect calling into an unknown and changeable in the future set of functions (since it waits for them to finish), and it seems error-prone to hold a lock across such a call.
> This will almost work, as long as it's done in workqueue.c with > appropriate locking. The bug occurs when some other CPU is running > phy_change() right now - we'll end up freeing data which that CPU is > presently playing with. > > But perhaps we can take care of this within workqueue.c. We need a > cancel function which will cancel the work and, if its callback is > presently executing it will block until that execution has completed.
I may be misunderstanding you, but this seems to deadlock in exactly the same way: if someone calls this cancel routine holding rtnl_lock, and the work function that will also take rtnl_lock has just started, it will get stuck when the work function tries to take rtnl_lock.
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