linux-kernel - Re: [PATCH] block: switch to pr_warn() in __device_add

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Message-ID: <20201011153259.GA637021@thinkpad>
Date:   Sun, 11 Oct 2020 08:32:59 -0700
From:   Rustam Kovhaev <rkovhaev@...il.com>
To:     Hannes Reinecke <hare@...e.de>
Cc:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: switch to pr_warn() in __device_add_disk()

On Sun, Oct 11, 2020 at 04:53:22PM +0200, Hannes Reinecke wrote:
> On 10/11/20 3:03 PM, Rustam Kovhaev wrote:
> > syzbot triggered a warning while fuzzing with failslab fault injection
> > enabled
> > let's convert WARN_ON() to pr_warn()
> > 
> > Reported-and-tested-by: syzbot+f41893bb8c45cd18cf08@...kaller.appspotmail.com
> > Link: https://syzkaller.appspot.com/bug?extid=f41893bb8c45cd18cf08
> > Signed-off-by: Rustam Kovhaev <rkovhaev@...il.com>
> > ---
> >   block/genhd.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/block/genhd.c b/block/genhd.c
> > index 99c64641c314..be9ce35cf0fe 100644
> > --- a/block/genhd.c
> > +++ b/block/genhd.c
> > @@ -822,7 +822,8 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
> >   		/* Register BDI before referencing it from bdev */
> >   		dev->devt = devt;
> >   		ret = bdi_register(bdi, "%u:%u", MAJOR(devt), MINOR(devt));
> > -		WARN_ON(ret);
> > +		if (ret)
> > +			pr_warn("%s: failed to register backing dev info\n", disk->disk_name);
> >   		bdi_set_owner(bdi, dev);
> >   		blk_register_region(disk_devt(disk), disk->minors, NULL,
> >   				    exact_match, exact_lock, disk);
> > 
> Please, don't. Where is the point in continuing here?
> I'd rather have it fixed up properly, either by having a return value to
> __device_add_disk() or by allowing the caller to check (eg by checking
> GENHD_FL_UP) if the call succeeded.
thank you for the review, it makes sense.