From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony PERARD Subject: Re: [PATCH v3 05/18] xen: add xenstore watcher infrastructure Date: Tue, 11 Dec 2018 15:21:29 +0000 Message-ID: <20181211152129.GS18875@perard.uk.xensource.com> References: <1544525238-3527-1-git-send-email-paul.durrant@citrix.com> <1544525238-3527-6-git-send-email-paul.durrant@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1gWjrL-0001KP-DF for xen-devel@lists.xenproject.org; Tue, 11 Dec 2018 15:22:07 +0000 Content-Disposition: inline In-Reply-To: <1544525238-3527-6-git-send-email-paul.durrant@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: Paul Durrant Cc: Kevin Wolf , Stefano Stabellini , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org T24gVHVlLCBEZWMgMTEsIDIwMTggYXQgMTA6NDc6MDVBTSArMDAwMCwgUGF1bCBEdXJyYW50IHdy b3RlOgo+IEEgWGVuIFBWIGZyb250ZW5kIGNvbW11bmljYXRlcyBpdHMgc3RhdGUgdG8gdGhlIFBW IGJhY2tlbmQgYnkgd3JpdGluZyB0bwo+IHRoZSAnc3RhdGUnIGtleSBpbiB0aGUgZnJvbnRlbmQg YXJlYSBpbiB4ZW5zdG9yZS4gSXQgaXMgdGhlcmVmb3JlCj4gbmVjZXNzYXJ5IGZvciBhIFhlbkRl dmljZSBpbXBsZW1lbnRhdGlvbiB0byBiZSBub3RpZmllZCB3aGVuZXZlciB0aGUKPiB2YWx1ZSBv ZiB0aGlzIGtleSBjaGFuZ2VzLgo+IAo+IFRoaXMgcGF0Y2ggYWRkcyBjb2RlIHRvIGRvIHRoaXMg YXMgZm9sbG93czoKPiAKPiAtIGFuICdmZCBoYW5kbGVyJyBpcyByZWdpc3RlcmVkIG9uIHRoZSBs aWJ4ZW5zdG9yZSBoYW5kbGUgd2hpY2ggd2lsbCBiZQo+ICAgdHJpZ2dlcmVkIHdoZW5ldmVyIGEg J3dhdGNoJyBldmVudCBvY2N1cnMKPiAtIHByaW1pdGl2ZXMgYXJlIGFkZGVkIHRvIHhlbi1idXMt aGVscGVyIHRvIGFkZCBvciByZW1vdmUgd2F0Y2ggZXZlbnRzCj4gLSBhIGxpc3Qgb2YgTm90aWZp ZXIgb2JqZWN0cyBpcyBhZGRlZCB0byBYZW5CdXMgdG8gcHJvdmlkZSBhIG1lY2hhbmlzbQo+ICAg dG8gY2FsbCB0aGUgYXBwcm9wcmlhdGUgJ3dhdGNoIGhhbmRsZXInIHdoZW4gaXRzIGFzc29jaWF0 ZWQgZXZlbnQKPiAgIG9jY3Vycwo+IAo+IFRoZSB4ZW4tYmxvY2sgaW1wbGVtZW50YXRpb24gaXMg ZXh0ZW5kZWQgd2l0aCBhICdmcm9udGVuZF9jaGFuZ2VkJyBtZXRob2QsCj4gd2hpY2ggY2FsbHMg YXMteWV0IHN0dWIgJ2Nvbm5lY3QnIGFuZCAnZGlzY29ubmVjdCcgZnVuY3Rpb25zIHdoZW4gdGhl Cj4gcmVsZXZhbnQgZnJvbnRlbmQgc3RhdGUgdHJhbnNpdGlvbnMgb2NjdXIuIEEgc3Vic2VxdWVu dCBwYXRjaCB3aWxsIHN1cHBseQo+IGEgZnVsbCBpbXBsZW1lbnRhdGlvbiBmb3IgdGhlc2UgZnVu Y3Rpb25zLgo+IAo+IFNpZ25lZC1vZmYtYnk6IFBhdWwgRHVycmFudCA8cGF1bC5kdXJyYW50QGNp dHJpeC5jb20+CgpSZXZpZXdlZC1ieTogQW50aG9ueSBQRVJBUkQgPGFudGhvbnkucGVyYXJkQGNp dHJpeC5jb20+CgotLSAKQW50aG9ueSBQRVJBUkQKCl9fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fClhlbi1kZXZlbCBtYWlsaW5nIGxpc3QKWGVuLWRldmVsQGxp c3RzLnhlbnByb2plY3Qub3JnCmh0dHBzOi8vbGlzdHMueGVucHJvamVjdC5vcmcvbWFpbG1hbi9s aXN0aW5mby94ZW4tZGV2ZWw= From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57912) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWjrM-0005CV-38 for qemu-devel@nongnu.org; Tue, 11 Dec 2018 10:22:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWjrK-0002MJ-Fl for qemu-devel@nongnu.org; Tue, 11 Dec 2018 10:22:08 -0500 Date: Tue, 11 Dec 2018 15:21:29 +0000 From: Anthony PERARD Message-ID: <20181211152129.GS18875@perard.uk.xensource.com> References: <1544525238-3527-1-git-send-email-paul.durrant@citrix.com> <1544525238-3527-6-git-send-email-paul.durrant@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1544525238-3527-6-git-send-email-paul.durrant@citrix.com> Subject: Re: [Qemu-devel] [PATCH v3 05/18] xen: add xenstore watcher infrastructure List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Durrant Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, xen-devel@lists.xenproject.org, Kevin Wolf , Max Reitz , Stefano Stabellini 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 Reviewed-by: Anthony PERARD -- Anthony PERARD