From: Andrew Morton <akpm@osdl.org>
To: maneesh@in.ibm.com
Cc: viro@parcelfarce.linux.theplanet.co.uk,
linux-kernel@vger.kernel.org, mochel@osdl.org,
dipankar@in.ibm.com
Subject: Re: [PATCH] sysfs_remove_dir Vs dcache_readdir race fix
Date: Thu, 20 Nov 2003 07:17:09 -0800 [thread overview]
Message-ID: <20031120071709.0acf35aa.akpm@osdl.org> (raw)
In-Reply-To: <20031120102525.GD1367@in.ibm.com>
Maneesh Soni <maneesh@in.ibm.com> wrote:
>
> Actually race is not directly between dcache_readdir and sysfs_remove_dir but
> it is like this
>
> cpu 0 cpu 1
> dcache_dir_open()
> --> adds the cursor dentry
>
> sysfs_remove_dir()
> --> list_del_init cursor dentry
>
> dcache_readdir()
> --> loops forever on inititalized cursor dentry.
>
>
> Though all these operations happen under parent's i_sem, but it is dropped
> between ->open() and ->readdir() as both are different calls.
>
> I think people will also agree that there is no need for sysfs_remove_dir()
> to modify d_subdirs list.
Seems to me that the libfs code is fragile.
What happens if the dentry at filp->f_private_data gets moved to a
different directory after someone did dcache_dir_open()? Does the loop
in dcache_readdir() go infinite again?
next prev parent reply other threads:[~2003-11-20 15:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-20 5:47 [PATCH] sysfs_remove_dir Vs dcache_readdir race fix Maneesh Soni
2003-11-20 5:49 ` viro
2003-11-20 5:56 ` Maneesh Soni
2003-11-20 10:25 ` Maneesh Soni
2003-11-20 15:17 ` Andrew Morton [this message]
2003-11-20 16:40 ` Dipankar Sarma
2003-11-20 18:44 ` viro
2003-11-20 18:43 ` viro
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