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d="scan'208";a="12824495" Date: Fri, 21 Feb 2020 15:26:35 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich Message-ID: <20200221142635.GA4679@Air-de-Roger> References: <20200220173116.88915-1-roger.pau@citrix.com> <83d48223-21eb-be54-985c-085449661892@xen.org> <20200221091005.GT4679@Air-de-Roger> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: AMSPEX02CAS02.citrite.net (10.69.22.113) To AMSPEX02CL01.citrite.net (10.69.22.125) Subject: Re: [Xen-devel] [PATCH v2] rwlock: allow recursive read locking when already locked in write mode X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?B?SsO8cmdlbiBHcm/Dnw==?= , Stefano Stabellini , Julien Grall , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , xen-devel@lists.xenproject.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" T24gRnJpLCBGZWIgMjEsIDIwMjAgYXQgMDI6MzY6NTJQTSArMDEwMCwgSmFuIEJldWxpY2ggd3Jv dGU6Cj4gT24gMjEuMDIuMjAyMCAxMDoxMCwgUm9nZXIgUGF1IE1vbm7DqSB3cm90ZToKPiA+IE9u IFRodSwgRmViIDIwLCAyMDIwIGF0IDA3OjIwOjA2UE0gKzAwMDAsIEp1bGllbiBHcmFsbCB3cm90 ZToKPiA+PiBIaSwKPiA+Pgo+ID4+IE9uIDIwLzAyLzIwMjAgMTc6MzEsIFJvZ2VyIFBhdSBNb25u ZSB3cm90ZToKPiA+Pj4gQWxsb3cgYSBDUFUgYWxyZWFkeSBob2xkaW5nIHRoZSBsb2NrIGluIHdy aXRlIG1vZGUgdG8gYWxzbyBsb2NrIGl0IGluCj4gPj4+IHJlYWQgbW9kZS4gVGhlcmUncyBubyBo YXJtIGluIGFsbG93aW5nIHJlYWQgbG9ja2luZyBhIHJ3bG9jayB0aGF0J3MKPiA+Pj4gYWxyZWFk eSBvd25lZCBieSB0aGUgY2FsbGVyIChpZTogQ1BVKSBpbiB3cml0ZSBtb2RlLiBBbGxvd2luZyBz dWNoCj4gPj4+IGFjY2Vzc2VzIGlzIHJlcXVpcmVkIGF0IGxlYXN0IGZvciB0aGUgQ1BVIG1hcHMg dXNlLWNhc2UuCj4gPj4+Cj4gPj4+IEluIG9yZGVyIHRvIGRvIHRoaXMgcmVzZXJ2ZSAxNGJpdHMg b2YgdGhlIGxvY2ssIHRoaXMgYWxsb3dzIHRvIHN1cHBvcnQKPiA+Pj4gdXAgdG8gMTYzODQgQ1BV cy4gQWxzbyByZWR1Y2UgdGhlIHdyaXRlIGxvY2sgbWFzayB0byAyIGJpdHM6IG9uZSB0bwo+ID4+ PiBzaWduYWwgdGhlcmUgYXJlIHBlbmRpbmcgd3JpdGVycyB3YWl0aW5nIG9uIHRoZSBsb2NrIGFu ZCB0aGUgb3RoZXIgdG8KPiA+Pj4gc2lnbmFsIHRoZSBsb2NrIGlzIG93bmVkIGluIHdyaXRlIG1v ZGUuIE5vdGUgdGhlIHdyaXRlIHJlbGF0ZWQgZGF0YQo+ID4+PiBpcyB1c2luZyAxNmJpdHMsIHRo aXMgaXMgZG9uZSBpbiBvcmRlciB0byBiZSBhYmxlIHRvIGNsZWFyIGl0IChhbmQKPiA+Pj4gdGh1 cyByZWxlYXNlIHRoZSBsb2NrKSB1c2luZyBhIDE2Yml0IGF0b21pYyB3cml0ZS4KPiA+Pj4KPiA+ Pj4gVGhpcyByZWR1Y2VzIHRoZSBtYXhpbXVtIG51bWJlciBvZiBjb25jdXJyZW50IHJlYWRlcnMg ZnJvbSAxNjc3NzIxNiB0bwo+ID4+PiA2NTUzNiwgSSB0aGluayB0aGlzIHNob3VsZCBzdGlsbCBi ZSBlbm91Z2gsIG9yIGVsc2UgdGhlIGxvY2sgZmllbGQKPiA+Pj4gY2FuIGJlIGV4cGFuZGVkIGZy b20gMzIgdG8gNjRiaXRzIGlmIGFsbCBhcmNoaXRlY3R1cmVzIHN1cHBvcnQgYXRvbWljCj4gPj4+ IG9wZXJhdGlvbnMgb24gNjRiaXQgaW50ZWdlcnMuCj4gPj4KPiA+PiBGV0lXLCBhcm0zMiBpcyBh YmxlIHRvIHN1cHBvcnQgYXRvbWljIG9wZXJhdGlvbnMgb24gNjQtYml0IGludGVnZXJzLgo+ID4+ Cj4gPj4+ICAgc3RhdGljIGlubGluZSB2b2lkIF93cml0ZV91bmxvY2socndsb2NrX3QgKmxvY2sp Cj4gPj4+ICAgewo+ID4+PiAtICAgIC8qCj4gPj4+IC0gICAgICogSWYgdGhlIHdyaXRlciBmaWVs ZCBpcyBhdG9taWMsIGl0IGNhbiBiZSBjbGVhcmVkIGRpcmVjdGx5Lgo+ID4+PiAtICAgICAqIE90 aGVyd2lzZSwgYW4gYXRvbWljIHN1YnRyYWN0aW9uIHdpbGwgYmUgdXNlZCB0byBjbGVhciBpdC4K PiA+Pj4gLSAgICAgKi8KPiA+Pj4gLSAgICBhdG9taWNfc3ViKF9RV19MT0NLRUQsICZsb2NrLT5j bnRzKTsKPiA+Pj4gKyAgICAvKiBTaW5jZSB0aGUgd3JpdGVyIGZpZWxkIGlzIGF0b21pYywgaXQg Y2FuIGJlIGNsZWFyZWQgZGlyZWN0bHkuICovCj4gPj4+ICsgICAgQVNTRVJUKF9pc193cml0ZV9s b2NrZWRfYnlfbWUoYXRvbWljX3JlYWQoJmxvY2stPmNudHMpKSk7Cj4gPj4+ICsgICAgQlVJTERf QlVHX09OKF9RUl9TSElGVCAhPSAxNik7Cj4gPj4+ICsgICAgd3JpdGVfYXRvbWljKCh1aW50MTZf dCAqKSZsb2NrLT5jbnRzLCAwKTsKPiA+Pgo+ID4+IEkgdGhpbmsgdGhpcyBpcyBhbiBhYnVzZSB0 byBjYXN0IGFuIGF0b21pY190KCkgZGlyZWN0bHkgaW50byBhIHVpbnQxNl90LiBZb3UKPiA+PiB3 b3VsZCBhdCBsZWFzdCB3YW50IHRvIHVzZSAmbG9jay0+Y250cy5jb3VudGVyIGhlcmUuCj4gPiAK PiA+IFN1cmUsIEkgd2FzIHdvbmRlcmluZyBhYm91dCB0aGlzIG15c2VsZi4KPiA+IAo+ID4gV2ls bCB3YWl0IGZvciBtb3JlIGNvbW1lbnRzLCBub3Qgc3VyZSB3aGV0aGVyIHRoaXMgY2FuIGJlIGZp eGVkIHVwb24KPiA+IGNvbW1pdCBpZiB0aGVyZSBhcmUgbm8gb3RoZXIgaXNzdWVzLgo+IAo+IEl0 J3MgbW9yZSB0aGFuIGp1c3QgYWRkaW5nIGFub3RoZXIgZmllbGQgc3BlY2lmaWVyIGhlcmUuIEEg Y2FzdCBsaWtlCj4gdGhpcyBvbmUgaXMgZW5kaWFubmVzcy11bnNhZmUsIGFuZCBoZW5jZSBhIHRy YXAgd2FpdGluZyBmb3IgYSBiaWcKPiBlbmRpYW4gcG9ydCBhdHRlbXB0IHRvIGZhbGwgaW50by4g QXQgdGhlIHZlcnkgbGVhc3QgdGhpcyBzaG91bGQgY2F1c2UKPiBhIGJ1aWxkIGZhaWx1cmUgb24g YmlnIGVuZGlhbiBzeXN0ZW1zLCBldmVuIGJldHRlciB3b3VsZCBiZSBpZiBpdCB3YXMKPiBlbmRp YW5uZXNzLXNhZmUuCgpXaHkgZG9uJ3Qgd2UgbGVhdmUgdGhlIGF0b21pY19kZWMgdGhlbj8KClRo ZSBBU1NFUlQgSSd2ZSBhZGRlZCBjYW4gYmUgdHVybmVkIGludG8gYSBCVUdfT04sIGFuZCB0aGF0 J3MgbGlrZWx5CmV2ZW4gc2FmZXIgdGhhbiB3aGF0IHdlIGN1cnJlbnRseSBoYXZlLgoKVGhhbmtz LCBSb2dlci4KCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f Clhlbi1kZXZlbCBtYWlsaW5nIGxpc3QKWGVuLWRldmVsQGxpc3RzLnhlbnByb2plY3Qub3JnCmh0 dHBzOi8vbGlzdHMueGVucHJvamVjdC5vcmcvbWFpbG1hbi9saXN0aW5mby94ZW4tZGV2ZWw=