Re: [PATCH] devfs v194 available

[Alexander Viro]

On Tue, 9 Oct 2001, Richard Gooch wrote:

>   Hi, all. Version 194 of my devfs patch is now available from:
> http://www.atnf.csiro.au/~rgooch/linux/kernel-patches.html
> The devfs FAQ is also available here.
> 
> Patch directly available from:
> ftp://ftp.??.kernel.org/pub/linux/kernel/people/rgooch/v2.4/devfs-patch-current.gz
> 
> AND:
> ftp://ftp.atnf.csiro.au/pub/people/rgooch/linux/kernel-patches/v2.4/devfs-patch-current.gz
> 
> This is against 2.4.11-pre6. Highlights of this release:
> 
> - Fixed overrun in <devfs_link> by removing function (not needed)

... doesn't fix _under_run in try_modload() (see what happens if namelen is
255 and parent is devfs root)

... doesn't fix the deadlock introduced into -pre6 in place of symlink
races. That

    /*  Need to follow the link: this is a stack chomper  */
    down_read (&symlink_rwsem);
    retval = curr->registered ?
        search_for_entry (parent, curr->u.symlink.linkname,
                          curr->u.symlink.length, FALSE, FALSE, NULL,
                          TRUE) : NULL;
    up_read (&symlink_rwsem);

is a fairly bad idea.  Think what happens if somebody else tries to
acquire symlink_rwsem for write between two calls of down_read() in
that recursion.