Re: [PATCH] sysfs_remove_dir Vs dcache_readdir race fix

From: viro
Date: Thu Nov 20 2003 - 13:44:06 EST


On Thu, Nov 20, 2003 at 03:55:25PM +0530, Maneesh Soni 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.

Yes. Thanks for spotting...

> 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.

Agreed.
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