Re: [Xen-devel] [PATCH v3 05/18] xen: add xenstore watcher infrastructure

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, Dec 11, 2018 at 10:47:05AM +0000, Paul Durrant wrote:
> A Xen PV frontend communicates its state to the PV backend by writing to
> the 'state' key in the frontend area in xenstore. It is therefore
> necessary for a XenDevice implementation to be notified whenever the
> value of this key changes.
> 
> This patch adds code to do this as follows:
> 
> - an 'fd handler' is registered on the libxenstore handle which will be
>   triggered whenever a 'watch' event occurs
> - primitives are added to xen-bus-helper to add or remove watch events
> - a list of Notifier objects is added to XenBus to provide a mechanism
>   to call the appropriate 'watch handler' when its associated event
>   occurs
> 
> The xen-block implementation is extended with a 'frontend_changed' method,
> which calls as-yet stub 'connect' and 'disconnect' functions when the
> relevant frontend state transitions occur. A subsequent patch will supply
> a full implementation for these functions.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

-- 
Anthony PERARD

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