Re: usb/net/p54: trying to register non-static key in p54_unregister_leds
From: Andrey Konovalov
Date: Thu Sep 21 2017 - 14:22:51 EST
On Wed, Sep 20, 2017 at 9:55 PM, Johannes Berg
> On Wed, 2017-09-20 at 21:27 +0200, Christian Lamparter wrote:
>> It seems this is caused as a result of:
>> -> lock_map_acquire(&work->lockdep_map);
>> in flush_work() 
>> This was added by:
>> commit 0976dfc1d0cd80a4e9dfaf87bd8744612bde475a
>> Author: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
>> Date: Fri Apr 20 17:28:50 2012 -0700
>> workqueue: Catch more locking problems with flush_work()
> Yes, but that doesn't matter.
>> Looking at the Stephen's patch, it's clear that it was made
>> with "static DECLARE_WORK(work, my_work)" in mind. However
>> p54's led_work is "per-device", hence it is stored in the
>> devices context p54_common, which is dynamically allocated.
>> So, maybe revert Stephen's patch?
> I disagree - as the lockdep warning says:
>> > INFO: trying to register non-static key.
>> > the code is fine but needs lockdep annotation.
>> > turning off the locking correctness validator.
> What it needs is to actually correctly go through initializing the work
> at least once.
> Without more information, I can't really say what's going on, but I
> assume that something is failing and p54_unregister_leds() is getting
> invoked without p54_init_leds() having been invoked, so essentially
> it's trying to flush a work that was never initialized?
> INIT_DELAYED_WORK() does, after all, initialize the lockdep map
> properly via __INIT_WORK().
Since I'm able to reproduce this, please let me know if you need me to
collect some debug traces to help with the triage.
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