linux-kernel - Re: [PATCH 2.6.18] sysfs: remove duplicated dput in sysfs_update

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Message-ID: <20060921031921.GA7183@in.ibm.com>
Date:	Thu, 21 Sep 2006 08:49:21 +0530
From:	Maneesh Soni <maneesh@...ibm.com>
To:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc:	Greg KH <gregkh@...e.de>,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2.6.18] sysfs: remove duplicated dput in sysfs_update_file

On Wed, Sep 20, 2006 at 04:38:00PM +0900, Hidetoshi Seto wrote:
> 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@...fujitsu.com>
> 
> ---
>  fs/sysfs/file.c |    5 -----
>  1 files changed, 5 deletions(-)
> 
> Index: linux-2.6.18/fs/sysfs/file.c
> ===================================================================
> --- linux-2.6.18.orig/fs/sysfs/file.c
> +++ linux-2.6.18/fs/sysfs/file.c
> @@ -483,11 +483,6 @@
>  		    (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);
> 
> -
> 

Looks good to me..

Thanks
Maneesh
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