From: Luis Chamberlain <mcgrof@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: 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, 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: Mon, 11 May 2020 13:39:00 +0000 [thread overview]
Message-ID: <20200511133900.GL11244@42.do-not-panic.com> (raw)
In-Reply-To: <e728acea-61c1-fcb5-489b-9be8cafe61ea@acm.org>
On Sat, May 09, 2020 at 06:09:38PM -0700, Bart Van Assche wrote:
> 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?
We'd have to add something like a linked list. Right now I'm just
clarifying things which were not clear before. What you describe is
a functional feature change. I'm just trying to fix a bug and clarify
limitations.
> 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?
blk device argument can be NULL here. sg-generic is one case.
Luis
next prev parent reply other threads:[~2020-05-11 13:39 UTC|newest]
Thread overview: 16+ 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
2020-05-11 13:39 ` Luis Chamberlain [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200511133900.GL11244@42.do-not-panic.com \
--to=mcgrof@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=gregkh@linuxfoundation.org \
--cc=jack@suse.cz \
--cc=linux-block@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@suse.com \
--cc=ming.lei@redhat.com \
--cc=mingo@redhat.com \
--cc=nstange@suse.de \
--cc=rostedt@goodmis.org \
--cc=viro@zeniv.linux.org.uk \
--cc=yukuai3@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).