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From: Bart Van Assche <bvanassche@acm.org>
To: Luis Chamberlain <mcgrof@kernel.org>,
	axboe@kernel.dk, viro@zeniv.linux.org.uk,
	gregkh@linuxfoundation.org, rostedt@goodmis.org,
	mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com,
	nstange@suse.de, akpm@linux-foundation.org
Cc: 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 v4 4/5] blktrace: break out of blktrace setup on concurrent calls
Date: Sat, 9 May 2020 18:09:38 -0700	[thread overview]
Message-ID: <e728acea-61c1-fcb5-489b-9be8cafe61ea@acm.org> (raw)
In-Reply-To: <20200509031058.8239-5-mcgrof@kernel.org>

On 2020-05-08 20:10, Luis Chamberlain wrote:
> @@ -493,6 +496,12 @@ 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 on %s\n",
> +			buts->name);
> +		return -EBUSY;
> +	}
> +
>  	bt = kzalloc(sizeof(*bt), GFP_KERNEL);
>  	if (!bt)
>  		return -ENOMEM;

Is this really sufficient? Shouldn't concurrent do_blk_trace_setup()
calls that refer to the same request queue be serialized to really
prevent that debugfs attribute creation fails?

How about using the block device name instead of the partition name in
the error message since the concurrency context is the block device and
not the partition?

Thanks,

Bart.



  reply	other threads:[~2020-05-10  1:09 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-09  3:10 [PATCH v4 0/5] block: fix blktrace debugfs use after free Luis Chamberlain
2020-05-09  3:10 ` [PATCH v4 1/5] block: revert back to synchronous request_queue removal Luis Chamberlain
2020-05-10  0:36   ` Bart Van Assche
2020-05-10  6:20   ` Greg KH
2020-05-11 13:41     ` Luis Chamberlain
2020-05-09  3:10 ` [PATCH v4 2/5] block: move main block debugfs initialization to its own file Luis Chamberlain
2020-05-09  3:10 ` [PATCH v4 3/5] blktrace: fix debugfs use after free Luis Chamberlain
2020-05-10  0:58   ` Bart Van Assche
2020-05-11 13:44     ` Luis Chamberlain
2020-05-10  6:26   ` Greg KH
2020-05-11 14:03     ` Luis Chamberlain
2020-05-09  3:10 ` [PATCH v4 4/5] blktrace: break out of blktrace setup on concurrent calls Luis Chamberlain
2020-05-10  1:09   ` Bart Van Assche [this message]
2020-05-11 13:39     ` Luis Chamberlain
2020-05-16  1:39       ` Luis Chamberlain
2020-05-16  1:39         ` Luis Chamberlain
2020-05-09  3:10 ` [PATCH v4 5/5] loop: be paranoid on exit and prevent new additions / removals Luis Chamberlain

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