From: Davidlohr Bueso <dave@stgolabs.net>
To: dsterba@suse.cz, Su Yue <l@damenly.su>,
linux-btrfs@vger.kernel.org, stable@vger.kernel.org,
Erhard F <erhard_f@mailbox.org>,
dave@stgolabs.net
Subject: Re: [PATCH] btrfs: fix lockdep warning due to seqcount_mutex_init() with wrong address
Date: Mon, 25 Jan 2021 23:03:11 -0800 [thread overview]
Message-ID: <20210126070311.wusdu3sfi6ywdrzb@offworld> (raw)
In-Reply-To: <20210125165346.GM1993@twin.jikos.cz>
On Mon, 25 Jan 2021, David Sterba wrote:
>IMO it's not, though some kind of annotation could be useful. The patch
>introducing the seqcount mutex does not mention any warning so it's
>probably meant only for clarity of the lock nesting or maybe real-time
>related as there are some comments regarding that in seqlock.h.
That lockdep_assert_held() is just to verify the writer side is properly
serialized. The real-time aspects here does not apply in that the mutex
is always preemptible.
>
>Even for a dynamic allocation we'd need a way to synchronize setting the
>variable, it could be possible, but the lockdep report needs to be
>fixed. Right now I don't see another way than the revert.
Agreed, let's revert this until a proper workaround is found.
Thanks,
Davidlohr
prev parent reply other threads:[~2021-01-26 18:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 11:39 [PATCH] btrfs: fix lockdep warning due to seqcount_mutex_init() with wrong address Su Yue
2021-01-21 17:07 ` David Sterba
2021-01-22 4:53 ` Su Yue
2021-01-25 16:53 ` David Sterba
2021-01-26 7:03 ` Davidlohr Bueso [this message]
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