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

On Fri, 3 Sep 2021 18:46:26 -0700
Luis Chamberlain [off-list ref] wrote:

On Fri, Sep 03, 2021 at 04:08:48PM +0200, Heiko Carstens wrote:

quoted

On Thu, Sep 02, 2021 at 10:41:03AM -0700, Luis Chamberlain wrote:

quoted

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