Re: [PATCH] lightnvm: propagate device_add() error code

device_add() may fail, and all callers are supposed to check the
return value, but one new user in lightnvm doesn't:

drivers/lightnvm/sysfs.c: In function 'nvm_sysfs_register_dev':
drivers/lightnvm/sysfs.c:184:2: error: ignoring return value of 'device_add', declared with attribute warn_unused_result [-Werror=unused-result]

This changes the caller to propagate any error codes, which avoids
the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 38c9e260b9f9 ("lightnvm: expose device geometry through sysfs")
---
  drivers/lightnvm/lightnvm.h | 2 +-
  drivers/lightnvm/sysfs.c    | 9 ++++++---
  2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/lightnvm/lightnvm.h b/drivers/lightnvm/lightnvm.h
index 93f1aacc9f02..305c181509a6 100644
--- a/drivers/lightnvm/lightnvm.h
+++ b/drivers/lightnvm/lightnvm.h

@@ -24,7 +24,7 @@
  #include <linux/lightnvm.h>

  /* core -> sysfs.c */
-int nvm_sysfs_register_dev(struct nvm_dev *);
+int __must_check nvm_sysfs_register_dev(struct nvm_dev *);
  void nvm_sysfs_unregister_dev(struct nvm_dev *);
  int nvm_sysfs_register(void);
  void nvm_sysfs_unregister(void);

diff --git a/drivers/lightnvm/sysfs.c b/drivers/lightnvm/sysfs.c
index 72ad089c0269..0338c27ab95a 100644
--- a/drivers/lightnvm/sysfs.c
+++ b/drivers/lightnvm/sysfs.c

@@ -174,6 +174,8 @@ static struct device_type nvm_type = {

  int nvm_sysfs_register_dev(struct nvm_dev *dev)
  {
+	int ret;
+
  	if (!dev->parent_dev)
  		return 0;

@@ -181,11 +183,12 @@ int nvm_sysfs_register_dev(struct nvm_dev *dev)
  	dev_set_name(&dev->dev, "%s", dev->name);
  	dev->dev.type = &nvm_type;
  	device_initialize(&dev->dev);
-	device_add(&dev->dev);
+	ret = device_add(&dev->dev);

-	blk_mq_register_dev(&dev->dev, dev->q);
+	if (!ret)
+		blk_mq_register_dev(&dev->dev, dev->q);

-	return 0;
+	return ret;
  }

  void nvm_sysfs_unregister_dev(struct nvm_dev *dev)