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[157.230.128.187]) by smtp.gmail.com with ESMTPSA id p16sm15627pjz.2.2020.05.01.08.06.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 May 2020 08:06:27 -0700 (PDT) Received: by 42.do-not-panic.com (Postfix, from userid 1000) id CABA44046C; Fri, 1 May 2020 15:06:26 +0000 (UTC) Date: Fri, 1 May 2020 15:06:26 +0000 From: Luis Chamberlain To: Greg KH Cc: axboe@kernel.dk, viro@zeniv.linux.org.uk, bvanassche@acm.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 Subject: Re: [PATCH v3 5/6] blktrace: break out of blktrace setup on concurrent calls Message-ID: <20200501150626.GM11244@42.do-not-panic.com> References: <20200429074627.5955-1-mcgrof@kernel.org> <20200429074627.5955-6-mcgrof@kernel.org> <20200429094937.GB2081185@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200429094937.GB2081185@kroah.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 29, 2020 at 11:49:37AM +0200, Greg KH wrote: > On Wed, Apr 29, 2020 at 07:46:26AM +0000, Luis Chamberlain wrote: > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > > index 5c52976bd762..383045f67cb8 100644 > > --- a/kernel/trace/blktrace.c > > +++ b/kernel/trace/blktrace.c > > @@ -516,6 +518,11 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, > > */ > > strreplace(buts->name, '/', '_'); > > > > + if (q->blk_trace) { > > + pr_warn("Concurrent blktraces are not allowed\n"); > > + return -EBUSY; > > You have access to a block device here, please use dev_warn() instead > here for that, that makes it obvious as to what device a "concurrent > blktrace" was attempted for. The block device may be empty, one example is for scsi-generic, but I'll use buts->name. Luis