Re: [PATCH UPDATED] xen: add xenfs to allow usermode <-> Xeninteraction

[Andrew Morton]

On Wed, 17 Dec 2008 13:24:39 -0800
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> The xenfs filesystem exports various interfaces to usermode.  Initially
> this exports a file to allow usermode to interact with xenbus/xenstore.
> 
> Traditionally this appeared in /proc/xen.  Rather than extending procfs,
> this patch adds a backward-compat mountpoint on /proc/xen, and provides
> a xenfs filesystem which can be mounted there.
> 
> [ 
>   I did quite a lot of work to this code as a result of review, which is
>   why this is a repost rather than a delta.  The changes are:
> 
>    - Moved the XENFS_SUPER_MAGIC to linux/magic.h
>    - Added comments to answer the "what's this for?" questions (I hope)
>    - Split things out into smaller functions
>    - Cleaned up type of queue_reply(), removed casts
>    - Added a mutex to protect struct xenbus_file_priv.  This protects
>       the list heads, and the partial message buffer.  There were
>       several ways in which usermode could overwrite the kernel's
>       memory via races without this locking.
>    - Fixed a bug in which usermode could start sending a message
>       which can never be sent, leaving the file descriptor in a
>       useless state.

I'm bored of your filesystem, so I think I'll just merge it, unless
someone else wants to ;)


Was this noticed and considered?

WARNING: consider using strict_strtoul in preference to simple_strtoul
#543: FILE: drivers/xen/xenfs/xenbus.c:315:
+               trans->handle.id = simple_strtoul(reply, NULL, 0);

total: 0 errors, 1 warnings, 781 lines checked

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