Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 14 Apr 2020 23:46:44 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>, axboe@kernel.dk,
        viro@zeniv.linux.org.uk, bvanassche@acm.org,
        gregkh@linuxfoundation.org, rostedt@goodmis.org, mingo@redhat.com,
        jack@suse.cz, ming.lei@redhat.com, nstange@suse.de,
        akpm@linux-foundation.org, mhocko@suse.com, yukuai3@huawei.com,
        linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Omar Sandoval <osandov@fb.com>,
        Hannes Reinecke <hare@suse.com>,
        Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH 5/5] block: revert back to synchronous request_queue
 removal
Message-ID: <20200415064644.GA28112@infradead.org>
References: <20200414041902.16769-1-mcgrof@kernel.org>
 <20200414041902.16769-6-mcgrof@kernel.org>
 <20200414154725.GD25765@infradead.org>
 <20200414205852.GP11244@42.do-not-panic.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200414205852.GP11244@42.do-not-panic.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Apr 14, 2020 at 08:58:52PM +0000, Luis Chamberlain wrote:
> > I think this needs a WARN_ON thrown in to enforece the calling context.
> 
> I considered adding a might_sleep() but upon review with Bart, he noted
> that this function already has a mutex_lock(), and if you look under the
> hood of mutex_lock(), it has a might_sleep() at the very top. The
> warning then is implicit.

It might just be a personal preference, but I think the documentation
value of a WARN_ON_ONCE or might_sleep with a comment at the top of
the function is much higher than a blurb in a long kerneldoc text and
a later mutex_lock.