+ sysfs-remove-duplicated-dput-in-sysfs_update_file.patch added to -mm tree

[akpm@xxxxxxxx]

The patch titled

     sysfs: remove duplicated dput in sysfs_update_file

has been added to the -mm tree.  Its filename is

     sysfs-remove-duplicated-dput-in-sysfs_update_file.patch

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: sysfs: remove duplicated dput in sysfs_update_file
From: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>

Following function can drops d_count twice against one reference
by lookup_one_len.

<SOURCE>
/**
 * sysfs_update_file - update the modified timestamp on an object attribute.
 * @kobj: object we're acting for.
 * @attr: attribute descriptor.
 */
int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
{
        struct dentry * dir = kobj->dentry;
        struct dentry * victim;
        int res = -ENOENT;

        mutex_lock(&dir->d_inode->i_mutex);
        victim = lookup_one_len(attr->name, dir, strlen(attr->name));
        if (!IS_ERR(victim)) {
                /* make sure dentry is really there */
                if (victim->d_inode &&
                    (victim->d_parent->d_inode == dir->d_inode)) {
                        victim->d_inode->i_mtime = CURRENT_TIME;
                        fsnotify_modify(victim);

                        /**
                         * Drop reference from initial sysfs_get_dentry().
                         */
                        dput(victim);
                        res = 0;
                } else
                        d_drop(victim);

                /**
                 * Drop the reference acquired from sysfs_get_dentry() above.
                 */
                dput(victim);
        }
        mutex_unlock(&dir->d_inode->i_mutex);

        return res;
}
</SOURCE>

PCI-hotplug (drivers/pci/hotplug/pci_hotplug_core.c) is only user of
this function. I confirmed that dentry of /sys/bus/pci/slots/XXX/*
have negative d_count value.

This patch removes unnecessary dput().

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---

 fs/sysfs/file.c |    5 -----
 1 files changed, 5 deletions(-)

diff -puN fs/sysfs/file.c~sysfs-remove-duplicated-dput-in-sysfs_update_file fs/sysfs/file.c
--- a/fs/sysfs/file.c~sysfs-remove-duplicated-dput-in-sysfs_update_file
+++ a/fs/sysfs/file.c
@@ -483,11 +483,6 @@ int sysfs_update_file(struct kobject * k
 		    (victim->d_parent->d_inode == dir->d_inode)) {
 			victim->d_inode->i_mtime = CURRENT_TIME;
 			fsnotify_modify(victim);
-
-			/**
-			 * Drop reference from initial sysfs_get_dentry().
-			 */
-			dput(victim);
 			res = 0;
 		} else
 			d_drop(victim);
_

Patches currently in -mm which might be from seto.hidetoshi@xxxxxxxxxxxxxx are

sysfs-remove-duplicated-dput-in-sysfs_update_file.patch
sysfs-update-obsolete-comment-in-sysfs_update_file.patch

-
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