Re: [Xen-devel] Re: [PATCH 2/3] xenoprof fixes: active_domains races

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 15 May 2006, at 18:34, Markus Armbruster wrote:

> The active_domains code has race conditions:
>
> * oprofile_set_active() calls set_active() method without holding
>   start_sem.  This is clearly wrong, as xenoprof_set_active() makes
>   several hypercalls.  oprofile_start(), for instance, could run in
>   the middle of xenoprof_set_active().
>
> * adomain_write(), adomain_read() and xenoprof_set_active() access
>   global active_domains[] and adomains without synchronization.  I
>   went for a simple, obvious fix and created another mutex.  Instead,
>   one could move the shared data into oprof.c and protect it with
>   start_sem, but that's more invasive.
>
> Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
Apart from updating to use the new mutex operations, patches 2 and 3 of 
your submitted set should be applied to 
patches/linux-2.6.16.13/xenoprof-generic.patch (yes, they need to be a 
patch of patch: sorry about that!). However, feel free to submit one 
mega-patch that merges both patches into one patch-of-a-patch.
 -- Keir


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