Re: [PATCH 7/9] s390/block/dcssblk: add error handling support for add_disk()

From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>,
	axboe@kernel.dk, gregkh@linuxfoundation.org,
	chaitanya.kulkarni@wdc.com, atulgopinathan@gmail.com,
	hare@suse.de, maximlevitsky@gmail.com, oakad@yahoo.com,
	ulf.hansson@linaro.org, colin.king@canonical.com,
	shubhankarvk@gmail.com, baijiaju1990@gmail.com, trix@redhat.com,
	dongsheng.yang@easystack.cn, ceph-devel@vger.kernel.org,
	miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com,
	sth@linux.ibm.com, hoeppner@linux.ibm.com, gor@linux.ibm.com,
	borntraeger@de.ibm.com, oberpar@linux.ibm.com, tj@kernel.org,
	linux-s390@vger.kernel.org, linux-mtd@lists.infradead.org,
	linux-mmc@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/9] s390/block/dcssblk: add error handling support for add_disk()
Date: Mon, 6 Sep 2021 13:43:46 +0200	[thread overview]
Message-ID: <20210906134346.19c14246@thinkpad> (raw)
In-Reply-To: <YTLP8mYBX37R++9E@bombadil.infradead.org>

On Fri, 3 Sep 2021 18:46:26 -0700
Luis Chamberlain <mcgrof@kernel.org> wrote:

> On Fri, Sep 03, 2021 at 04:08:48PM +0200, Heiko Carstens wrote:
> > On Thu, Sep 02, 2021 at 10:41:03AM -0700, Luis Chamberlain wrote:
> > > We never checked for errors on add_disk() as this function
> > > returned void. Now that this is fixed, use the shiny new
> > > error handling.
> > > 
> > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> > > ---
> > >  drivers/s390/block/dcssblk.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> > > index 5be3d1c39a78..b0fd5009a12e 100644
> > > --- a/drivers/s390/block/dcssblk.c
> > > +++ b/drivers/s390/block/dcssblk.c
> > > @@ -696,7 +696,9 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char
> > >  	}
> > >  
> > >  	get_device(&dev_info->dev);
> > > -	device_add_disk(&dev_info->dev, dev_info->gd, NULL);
> > > +	rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
> > > +	if (rc)
> > > +		goto put_dev;
> > 
> > This looks not correct to me. We seem to have now in case of an error:
> > 
> > - reference count imbalance (= memory leak)
> > - dax cleanup is missing
> 
> Care to provide an alternative?

See patch below:

From 7053b5f8c0a126c3ef450de3668d9963bd68ceaa Mon Sep 17 00:00:00 2001
From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Date: Mon, 6 Sep 2021 13:18:53 +0200
Subject: [PATCH] s390/block/dcssblk: add error handling support for add_disk()

Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
---
 drivers/s390/block/dcssblk.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 5be3d1c39a78..0741a9321712 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -696,7 +696,9 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char
 	}
 
 	get_device(&dev_info->dev);
-	device_add_disk(&dev_info->dev, dev_info->gd, NULL);
+	rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
+	if (rc)
+		goto out_dax;
 
 	switch (dev_info->segment_type) {
 		case SEG_TYPE_SR:
@@ -712,6 +714,10 @@ dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char
 	rc = count;
 	goto out;
 
+out_dax:
+	put_device(&dev_info->dev);
+	kill_dax(dev_info->dax_dev);
+	put_dax(dev_info->dax_dev);
 put_dev:
 	list_del(&dev_info->lh);
 	blk_cleanup_disk(dev_info->gd);
-- 
2.25.1

