From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751105AbdE3RJv (ORCPT ); Tue, 30 May 2017 13:09:51 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:27307 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751030AbdE3RJs (ORCPT ); Tue, 30 May 2017 13:09:48 -0400 Subject: Re: [PATCH] xen: don't print error message in case of missing Xenstore entry To: Juergen Gross , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org References: <20170529091339.1449-1-jgross@suse.com> <69e13959-26a5-a794-2fa7-3933bc6f22f0@oracle.com> <78ae3bc7-fbd9-5f69-3177-67eeb3f43201@suse.com> From: Boris Ostrovsky Message-ID: Date: Tue, 30 May 2017 13:08:25 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <78ae3bc7-fbd9-5f69-3177-67eeb3f43201@suse.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/30/2017 11:03 AM, Juergen Gross wrote: > On 30/05/17 15:25, Boris Ostrovsky wrote: >> On 05/29/2017 05:13 AM, Juergen Gross wrote: >>> When registering for the Xenstore watch of the node control/sysrq the >>> handler will be called at once. Don't issue an error message if the >>> Xenstore node isn't there, as it will be created only when an event >>> is being triggered. >>> >>> Signed-off-by: Juergen Gross >>> --- >>> drivers/xen/manage.c | 7 +++++-- >>> 1 file changed, 5 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c >>> index c1ec8ee80924..7ddd0803da23 100644 >>> --- a/drivers/xen/manage.c >>> +++ b/drivers/xen/manage.c >>> @@ -277,8 +277,11 @@ static void sysrq_handler(struct xenbus_watch *watch, const char *path, >>> err = xenbus_transaction_start(&xbt); >>> if (err) >>> return; >>> - if (xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key) < 0) { >>> - pr_err("Unable to read sysrq code in control/sysrq\n"); >>> + err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key); >>> + if (err < 0) { >>> + if (err != -ENOENT) >> Can we distinguish initialization invocation from actual watch firing? >> E.g. '|| (system_state >= SYSTEM_RUNNING)'? > The watch will fire again after suspend/resume (e.g. live migration). That's unfortunate. (And system_state check would also not be a good solution btw since the watch might be processed by the watch thread after we enter SYSTEM_RUNNING). Can you add a comment explaining why we are ignoring ENOENT? -boris > > > Juergen > >> -boris >> >>> + pr_err("Error %d reading sysrq code in control/sysrq\n", >>> + err); >>> xenbus_transaction_end(xbt, 1); >>> return; >>> } >> From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: [PATCH] xen: don't print error message in case of missing Xenstore entry Date: Tue, 30 May 2017 13:08:25 -0400 Message-ID: References: <20170529091339.1449-1-jgross@suse.com> <69e13959-26a5-a794-2fa7-3933bc6f22f0@oracle.com> <78ae3bc7-fbd9-5f69-3177-67eeb3f43201@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dFkdJ-00012A-Lf for xen-devel@lists.xenproject.org; Tue, 30 May 2017 17:08:37 +0000 In-Reply-To: <78ae3bc7-fbd9-5f69-3177-67eeb3f43201@suse.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Juergen Gross , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org T24gMDUvMzAvMjAxNyAxMTowMyBBTSwgSnVlcmdlbiBHcm9zcyB3cm90ZToKPiBPbiAzMC8wNS8x NyAxNToyNSwgQm9yaXMgT3N0cm92c2t5IHdyb3RlOgo+PiBPbiAwNS8yOS8yMDE3IDA1OjEzIEFN LCBKdWVyZ2VuIEdyb3NzIHdyb3RlOgo+Pj4gV2hlbiByZWdpc3RlcmluZyBmb3IgdGhlIFhlbnN0 b3JlIHdhdGNoIG9mIHRoZSBub2RlIGNvbnRyb2wvc3lzcnEgdGhlCj4+PiBoYW5kbGVyIHdpbGwg YmUgY2FsbGVkIGF0IG9uY2UuIERvbid0IGlzc3VlIGFuIGVycm9yIG1lc3NhZ2UgaWYgdGhlCj4+ PiBYZW5zdG9yZSBub2RlIGlzbid0IHRoZXJlLCBhcyBpdCB3aWxsIGJlIGNyZWF0ZWQgb25seSB3 aGVuIGFuIGV2ZW50Cj4+PiBpcyBiZWluZyB0cmlnZ2VyZWQuCj4+Pgo+Pj4gU2lnbmVkLW9mZi1i eTogSnVlcmdlbiBHcm9zcyA8amdyb3NzQHN1c2UuY29tPgo+Pj4gLS0tCj4+PiAgZHJpdmVycy94 ZW4vbWFuYWdlLmMgfCA3ICsrKysrLS0KPj4+ICAxIGZpbGUgY2hhbmdlZCwgNSBpbnNlcnRpb25z KCspLCAyIGRlbGV0aW9ucygtKQo+Pj4KPj4+IGRpZmYgLS1naXQgYS9kcml2ZXJzL3hlbi9tYW5h Z2UuYyBiL2RyaXZlcnMveGVuL21hbmFnZS5jCj4+PiBpbmRleCBjMWVjOGVlODA5MjQuLjdkZGQw ODAzZGEyMyAxMDA2NDQKPj4+IC0tLSBhL2RyaXZlcnMveGVuL21hbmFnZS5jCj4+PiArKysgYi9k cml2ZXJzL3hlbi9tYW5hZ2UuYwo+Pj4gQEAgLTI3Nyw4ICsyNzcsMTEgQEAgc3RhdGljIHZvaWQg c3lzcnFfaGFuZGxlcihzdHJ1Y3QgeGVuYnVzX3dhdGNoICp3YXRjaCwgY29uc3QgY2hhciAqcGF0 aCwKPj4+ICAJZXJyID0geGVuYnVzX3RyYW5zYWN0aW9uX3N0YXJ0KCZ4YnQpOwo+Pj4gIAlpZiAo ZXJyKQo+Pj4gIAkJcmV0dXJuOwo+Pj4gLQlpZiAoeGVuYnVzX3NjYW5mKHhidCwgImNvbnRyb2wi LCAic3lzcnEiLCAiJWMiLCAmc3lzcnFfa2V5KSA8IDApIHsKPj4+IC0JCXByX2VycigiVW5hYmxl IHRvIHJlYWQgc3lzcnEgY29kZSBpbiBjb250cm9sL3N5c3JxXG4iKTsKPj4+ICsJZXJyID0geGVu YnVzX3NjYW5mKHhidCwgImNvbnRyb2wiLCAic3lzcnEiLCAiJWMiLCAmc3lzcnFfa2V5KTsKPj4+ ICsJaWYgKGVyciA8IDApIHsKPj4+ICsJCWlmIChlcnIgIT0gLUVOT0VOVCkKPj4gQ2FuIHdlIGRp c3Rpbmd1aXNoIGluaXRpYWxpemF0aW9uIGludm9jYXRpb24gZnJvbSBhY3R1YWwgd2F0Y2ggZmly aW5nPwo+PiBFLmcuICd8fCAoc3lzdGVtX3N0YXRlID49IFNZU1RFTV9SVU5OSU5HKSc/Cj4gVGhl IHdhdGNoIHdpbGwgZmlyZSBhZ2FpbiBhZnRlciBzdXNwZW5kL3Jlc3VtZSAoZS5nLiBsaXZlIG1p Z3JhdGlvbikuCgoKVGhhdCdzIHVuZm9ydHVuYXRlLiAoQW5kIHN5c3RlbV9zdGF0ZSBjaGVjayB3 b3VsZCBhbHNvIG5vdCBiZSBhIGdvb2QKc29sdXRpb24gYnR3IHNpbmNlIHRoZSB3YXRjaCBtaWdo dCBiZSBwcm9jZXNzZWQgYnkgdGhlIHdhdGNoIHRocmVhZAphZnRlciB3ZSBlbnRlciBTWVNURU1f UlVOTklORykuCgpDYW4geW91IGFkZCBhIGNvbW1lbnQgZXhwbGFpbmluZyB3aHkgd2UgYXJlIGln bm9yaW5nIEVOT0VOVD8KCi1ib3JpcwoKCgo+Cj4KPiBKdWVyZ2VuCj4KPj4gLWJvcmlzCj4+Cj4+ PiArCQkJcHJfZXJyKCJFcnJvciAlZCByZWFkaW5nIHN5c3JxIGNvZGUgaW4gY29udHJvbC9zeXNy cVxuIiwKPj4+ICsJCQkgICAgICAgZXJyKTsKPj4+ICAJCXhlbmJ1c190cmFuc2FjdGlvbl9lbmQo eGJ0LCAxKTsKPj4+ICAJCXJldHVybjsKPj4+ICAJfQo+PgoKCl9fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fClhlbi1kZXZlbCBtYWlsaW5nIGxpc3QKWGVuLWRl dmVsQGxpc3RzLnhlbi5vcmcKaHR0cHM6Ly9saXN0cy54ZW4ub3JnL3hlbi1kZXZlbAo=