From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Hillf Danton <hdanton@sina.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
"Reviewed-by : Tyler Hicks" <tyhicks@linux.microsoft.com>,
linux-block@vger.kernel.org
Subject: [PATCH 7/7] loop: avoid holding loop_ctl_mutex over add_disk
Date: Wed, 18 Aug 2021 08:24:55 +0200 [thread overview]
Message-ID: <20210818062455.211065-8-hch@lst.de> (raw)
In-Reply-To: <20210818062455.211065-1-hch@lst.de>
To avoid complex lock ordering issues loop_ctl_mutex should not
be held over add_disk. Add a new Lo_new state for a loop device
that has just been created but which is not live yet.
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/block/loop.c | 16 ++++++++++++----
drivers/block/loop.h | 1 +
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 043673bda8b3..80f462edc39f 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2329,7 +2329,7 @@ static int loop_add(int i)
lo = kzalloc(sizeof(*lo), GFP_KERNEL);
if (!lo)
goto out;
- lo->lo_state = Lo_unbound;
+ lo->lo_state = Lo_new;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
@@ -2343,8 +2343,9 @@ static int loop_add(int i)
} else {
err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
}
+ mutex_unlock(&loop_ctl_mutex);
if (err < 0)
- goto out_unlock;
+ goto out_free_dev;
i = err;
err = -ENOMEM;
@@ -2414,15 +2415,22 @@ static int loop_add(int i)
disk->event_flags = DISK_EVENT_FLAG_UEVENT;
sprintf(disk->disk_name, "loop%d", i);
add_disk(disk);
+
+ err = mutex_lock_killable(&loop_ctl_mutex);
+ if (err)
+ goto out_del_gendisk;
+ lo->lo_state = Lo_unbound;
mutex_unlock(&loop_ctl_mutex);
+
return i;
+out_del_gendisk:
+ del_gendisk(lo->lo_disk);
+ blk_cleanup_disk(lo->lo_disk);
out_cleanup_tags:
blk_mq_free_tag_set(&lo->tag_set);
out_free_idr:
idr_remove(&loop_index_idr, i);
-out_unlock:
- mutex_unlock(&loop_ctl_mutex);
out_free_dev:
kfree(lo);
out:
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index d14ce6bdc014..608a20c23c64 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -24,6 +24,7 @@ enum {
Lo_bound,
Lo_rundown,
Lo_deleting,
+ Lo_new,
};
struct loop_func_table;
--
2.30.2
next prev parent reply other threads:[~2021-08-18 6:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 6:24 sort out the lock order in the loop driver Christoph Hellwig
2021-08-18 6:24 ` [PATCH 1/7] loop: remove the ->ioctl method in loop_func_table Christoph Hellwig
2021-08-18 6:24 ` [PATCH 2/7] loop: return void from the ->release " Christoph Hellwig
2021-08-18 6:24 ` [PATCH 3/7] loop: merge the cryptoloop module into the main loop module Christoph Hellwig
2021-08-18 6:24 ` [PATCH 4/7] loop: devirtualize transfer transformations Christoph Hellwig
2021-08-18 6:24 ` [PATCH 5/7] loop: remove the unused idx argument to loop_control_get_free Christoph Hellwig
2021-08-18 6:24 ` [PATCH 6/7] loop: move loop device deletion out of loop_ctl_mutex Christoph Hellwig
2021-08-18 6:24 ` Christoph Hellwig [this message]
2021-08-18 10:08 ` sort out the lock order in the loop driver Tetsuo Handa
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=20210818062455.211065-8-hch@lst.de \
--to=hch@lst.de \
--cc=axboe@kernel.dk \
--cc=hdanton@sina.com \
--cc=linux-block@vger.kernel.org \
--cc=pasha.tatashin@soleen.com \
--cc=penguin-kernel@i-love.sakura.ne.jp \
--cc=tyhicks@linux.microsoft.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).