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Subject: Re: [PATCH v2 3/3] driver core: Skip unnecessary work when device
 doesn't have sync_state()
From:   Davide Caratti <dcaratti@redhat.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Saravana Kannan <saravanak@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Vladimir Benes <vbenes@redhat.com>, kernel-team@android.com,
        linux-kernel@vger.kernel.org
In-Reply-To: <20200325074428.GA3014101@kroah.com>
References: <20200221080510.197337-1-saravanak@google.com>
         <20200221080510.197337-4-saravanak@google.com>
         <f22b7cd6fb6256f56e908e021f4fe389f3a6ee07.camel@redhat.com>
         <20200325074428.GA3014101@kroah.com>
Organization: red hat
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Date:   Wed, 25 Mar 2020 10:11:19 +0100
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On Wed, 2020-03-25 at 08:44 +0100, Greg Kroah-Hartman wrote:
> On Tue, Mar 24, 2020 at 09:03:28PM +0100, Davide Caratti wrote:
> > On Fri, 2020-02-21 at 00:05 -0800, Saravana Kannan wrote:
> > > A bunch of busy work is done for devices that don't have sync_state()
> > > support. Stop doing the busy work.
> > > 
> > > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > > ---
> > >  drivers/base/core.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > 
> > hello Greg,
> > 
> > this patch and patch 2/3 of the same series proved to fix systematic
> > crashes (NULL pointer dereference in device_links_flush_sync_list() while
> > loading mac80211_hwsim.ko, see [1]) on Fedora 31, that are triggered by
> > NetworkManager-ci [2]. May I ask to queue these two patches for the next
> > 5.5 stable?
> 
> What are the git commit ids of these patches in Linus's tree that you
> want backported?

right, I should have mentioned them also here: 

ac338acf514e "(driver core: Add dev_has_sync_state())" <-- patch 2/3 
77036165d8bc "(driver core: Skip unnecessary work when device doesn't have sync_state())" <-- patch 3/3

like Saravana mentioned, the problem is probably introduced by patch
1/3 of the series, 

77036165d8bc "(driver core: Skip unnecessary work when device doesn't have sync_state())"

that's already in stable 5.5.

thanks!
-- 
davide