linux-kernel - Build warning 'uninitialized variable' in fs/overlayfs

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Message-ID: <20170517202649.szj7ygjfnsgdpzl3@yury-N73SV>
Date:   Wed, 17 May 2017 23:26:49 +0300
From:   Yury Norov <ynorov@...iumnetworks.com>
To:     Amir Goldstein <amir73il@...il.com>,
        Miklos Szeredi <mszeredi@...hat.com>
Cc:     ynorov@...iumnetworks.com, linux-kernel@...r.kernel.org
Subject: Build warning 'uninitialized variable' in fs/overlayfs

Hi Amir,

(Sorry for new email, but I cannot find your patch in my mailbox,
though found it in next-20170517)

Your patch 02cac3227a282 (ovl: mark upper dir with type origin entries
"impure") makes gcc warn on uninitialized variables in my arm64 build:
fs/overlayfs/dir.c: In function ‘ovl_rename’:
fs/overlayfs/dir.c:1060:2: warning: ‘newdentry’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
dput(newdentry);
^~~~~~~~~~~~~~~
fs/overlayfs/dir.c:1062:2: warning: ‘olddentry’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
dput(olddentry);
^~~~~~~~~~~~~~~

The patch below fixes warnings for me. But I'm not familiar to the
subsystem and so not sure that the fix is correct.

Yury

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 5ad6ccf2159e..19ee4d294b5e 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -973,13 +973,13 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 		if (ovl_type_origin(old) && !ovl_type_merge(new->d_parent)) {
 			err = ovl_set_impure(new->d_parent, new_upperdir);
 			if (err)
-				goto out_dput;
+				goto out_unlock;
 		}
 		if (!overwrite && ovl_type_origin(new) &&
 		    !ovl_type_merge(old->d_parent)) {
 			err = ovl_set_impure(old->d_parent, old_upperdir);
 			if (err)
-				goto out_dput;
+				goto out_unlock;
 		}
 	}