From: Jens Axboe <axboe@kernel.dk>
To: Matthew Wilcox <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Benjamin LaHaise <bcrl@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Kees Cook <keescook@chromium.org>,
fsdevel <linux-fsdevel@vger.kernel.org>,
linux-aio@kvack.org, linux-mm <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH] aio: Convert ioctx_table to XArray
Date: Tue, 11 Dec 2018 11:46:53 -0700 [thread overview]
Message-ID: <75267003-9407-101f-33ee-685e345a2c8a@kernel.dk> (raw)
In-Reply-To: <20181211184553.GH6830@bombadil.infradead.org>
On 12/11/18 11:45 AM, Matthew Wilcox wrote:
> On Tue, Dec 11, 2018 at 11:41:55AM -0700, Jens Axboe wrote:
>> On Wed, Nov 28, 2018 at 11:35 AM Matthew Wilcox <willy@infradead.org> wrote:
>>>
>>> rcu_read_lock();
>>> - table = rcu_dereference(mm->ioctx_table);
>>> -
>>> - if (!table || id >= table->nr)
>>> - goto out;
>>> -
>>> - ctx = rcu_dereference(table->table[id]);
>>> + ctx = xa_load(&mm->ioctx, id);
>>> if (ctx && ctx->user_id == ctx_id) {
>>> if (percpu_ref_tryget_live(&ctx->users))
>>> ret = ctx;
>>> }
>>
>> Question on this part - do we need that RCU read lock around this now? I
>> don't think we do.
>
> I think we need the rcu read lock here to prevent ctx from being freed
> under us by free_ioctx().
Then that begs the question, how about __xa_load() that is already called
under RCU read lock?
--
Jens Axboe
next prev parent reply other threads:[~2018-12-11 18:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 18:35 [PATCH] aio: Convert ioctx_table to XArray Matthew Wilcox
2018-12-06 21:08 ` Matthew Wilcox
2018-12-06 22:21 ` Jeff Moyer
2018-12-06 22:21 ` Jeff Moyer
2018-12-06 22:26 ` Jeff Moyer
2018-12-06 22:26 ` Jeff Moyer
2018-12-11 17:21 ` Jeff Moyer
2018-12-11 17:21 ` Jeff Moyer
2018-12-11 17:51 ` Matthew Wilcox
2018-12-11 18:02 ` Jeff Moyer
2018-12-11 18:02 ` Jeff Moyer
2018-12-11 18:05 ` Jens Axboe
2018-12-11 18:09 ` Jeff Moyer
2018-12-11 18:09 ` Jeff Moyer
2018-12-11 18:37 ` Jens Axboe
2018-12-11 18:32 ` Jens Axboe
2018-12-11 18:36 ` Jens Axboe
2018-12-11 18:51 ` Matthew Wilcox
2018-12-11 18:52 ` Jens Axboe
2018-12-11 18:41 ` Jens Axboe
2018-12-11 18:41 ` Jens Axboe
2018-12-11 18:45 ` Matthew Wilcox
2018-12-11 18:46 ` Jens Axboe [this message]
2018-12-11 18:53 ` Matthew Wilcox
2018-12-11 18:54 ` Jens Axboe
2018-12-11 18:53 ` Jens Axboe
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=75267003-9407-101f-33ee-685e345a2c8a@kernel.dk \
--to=axboe@kernel.dk \
--cc=akpm@linux-foundation.org \
--cc=bcrl@kvack.org \
--cc=dan.carpenter@oracle.com \
--cc=keescook@chromium.org \
--cc=linux-aio@kvack.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.