Re: [Xen-devel] Re: [PATCH 3/4] [Net] Support Xen accelerated network plugin modules

[Kieran Mansley <kmansley@xxxxxxxxxxxxxx>]

On Tue, 2007-05-22 at 08:48 +0100, Keir Fraser wrote:
> 
> 
> On 22/5/07 08:28, "Kieran Mansley" <kmansley@xxxxxxxxxxxxxx> wrote:
> 
> > On Tue, 2007-05-22 at 08:15 +0100, Kieran Mansley wrote:
> >> RCU on its own wouldn't
> >> prevent the accelerated plugin being unloaded while netfront was using
> >> one of the hooks.
> > 
> > Hmm, actually I think it could be used to do that.  I'll take a look.
> 
> Eagerly zap the function pointers, then wait one RCU period so every CPU
> goes through a quiescent point before unloading the module?
> 
>  -- Keir

Am I right in thinking that if one of the functions that was protected
by RCU was to block, that would be a bad thing?  Clearly the data path
hooks can't/don't block, but I'm not sure it's so obvious for things
like probing a new device. 

Kieran


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