From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: "jack@suse.cz" , "joseph.qi@linux.alibaba.com" , "axboe@kernel.dk" CC: "hch@lst.de" , "linux-block@vger.kernel.org" Subject: Re: [PATCH v2 2/2] block: Fix a race between the throttling code and request queue initialization Date: Mon, 5 Feb 2018 17:58:12 +0000 Message-ID: <1517853491.3764.26.camel@wdc.com> References: <20180131235300.12773-1-bart.vanassche@wdc.com> <20180131235300.12773-3-bart.vanassche@wdc.com> <1ff1b2fa-ffe1-20f4-6be9-919c6a5b8227@linux.alibaba.com> <1517501761.2746.21.camel@wdc.com> <26f758cf-430c-aa7f-0d21-75fbad6db260@gmail.com> <1517588518.2675.14.camel@wdc.com> <63bb4057-d502-69cd-0385-10ae33bd6649@linux.alibaba.com> In-Reply-To: <63bb4057-d502-69cd-0385-10ae33bd6649@linux.alibaba.com> Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 List-ID: T24gU2F0LCAyMDE4LTAyLTAzIGF0IDEwOjUxICswODAwLCBKb3NlcGggUWkgd3JvdGU6DQo+IEhp IEJhcnQsDQo+IA0KPiBPbiAxOC8yLzMgMDA6MjEsIEJhcnQgVmFuIEFzc2NoZSB3cm90ZToNCj4g PiBPbiBGcmksIDIwMTgtMDItMDIgYXQgMDk6MDIgKzA4MDAsIEpvc2VwaCBRaSB3cm90ZToNCj4g PiA+IFdlIHRyaWdnZXJlZCB0aGlzIHJhY2Ugd2hlbiB1c2luZyBzaW5nbGUgcXVldWUuIEknbSBu b3Qgc3VyZSBpZiBpdA0KPiA+ID4gZXhpc3RzIGluIG11bHRpLXF1ZXVlLg0KPiA+IA0KPiA+IFJl Z2FyZGluZyB0aGUgcmFjZXMgYmV0d2VlbiBtb2RpZnlpbmcgdGhlIHF1ZXVlX2xvY2sgcG9pbnRl ciBhbmQgdGhlIGNvZGUgdGhhdA0KPiA+IHVzZXMgdGhhdCBwb2ludGVyLCBJIHRoaW5rIHRoZSBm b2xsb3dpbmcgY29uc3RydWN0IGluIGJsa19jbGVhbnVwX3F1ZXVlKCkgaXMNCj4gPiBzdWZmaWNp ZW50IHRvIGF2b2lkIHJhY2VzIGJldHdlZW4gdGhlIHF1ZXVlX2xvY2sgcG9pbnRlciBhc3NpZ25t ZW50IGFuZCB0aGUgY29kZQ0KPiA+IHRoYXQgZXhlY3V0ZXMgY29uY3VycmVudGx5IHdpdGggYmxr X2NsZWFudXBfcXVldWUoKToNCj4gPiANCj4gPiAJc3Bpbl9sb2NrX2lycShsb2NrKTsNCj4gPiAJ aWYgKHEtPnF1ZXVlX2xvY2sgIT0gJnEtPl9fcXVldWVfbG9jaykNCj4gPiAJCXEtPnF1ZXVlX2xv Y2sgPSAmcS0+X19xdWV1ZV9sb2NrOw0KPiA+IAlzcGluX3VubG9ja19pcnEobG9jayk7DQo+ID4g DQo+IA0KPiBJTU8sIHRoZSByYWNlIGFsc28gZXhpc3RzLg0KPiANCj4gYmxrX2NsZWFudXBfcXVl dWUgICAgICAgICAgICAgICAgICAgYmxrY2dfcHJpbnRfYmxrZ3MNCj4gICBzcGluX2xvY2tfaXJx KGxvY2spICgxKSAgICAgICAgICAgc3Bpbl9sb2NrX2lycShibGtnLT5xLT5xdWV1ZV9sb2NrKSAo Miw1KQ0KPiAgICAgcS0+cXVldWVfbG9jayA9ICZxLT5fX3F1ZXVlX2xvY2sgKDMpDQo+ICAgc3Bp bl91bmxvY2tfaXJxKGxvY2spICg0KQ0KPiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICBzcGluX3VubG9ja19pcnEoYmxrZy0+cS0+cXVldWVfbG9jaykgKDYpDQo+IA0KPiAoMSkg dGFrZSBkcml2ZXIgbG9jazsNCj4gKDIpIGJ1c3kgbG9vcCBmb3IgZHJpdmVyIGxvY2s7DQo+ICgz KSBvdmVycmlkZSBkcml2ZXIgbG9jayB3aXRoIGludGVybmFsIGxvY2s7DQo+ICg0KSB1bmxvY2sg ZHJpdmVyIGxvY2s7IA0KPiAoNSkgY2FuIHRha2UgZHJpdmVyIGxvY2sgbm93Ow0KPiAoNikgYnV0 IHVubG9jayBpbnRlcm5hbCBsb2NrLg0KPiANCj4gSWYgd2UgZ2V0IGJsa2ctPnEtPnF1ZXVlX2xv Y2sgdG8gbG9jYWwgZmlyc3QgbGlrZSBibGtfY2xlYW51cF9xdWV1ZSwNCj4gaXQgaW5kZWVkIGNh biBmaXggdGhlIGRpZmZlcmVudCBsb2NrIHVzZSBpbiBsb2NrL3VubG9jay4gQnV0IHNpbmNlDQo+ IGJsa19jbGVhbnVwX3F1ZXVlIGhhcyBvdmVycmlkZGVuIHF1ZXVlIGxvY2sgdG8gaW50ZXJuYWwg bG9jayBub3csIEknbQ0KPiBhZnJhaWQgd2UgY291bGRuJ3Qgc3RpbGwgdXNlIGRyaXZlciBsb2Nr IGluIGJsa2NnX3ByaW50X2Jsa2dzLg0KDQooKyBKYW4gS2FyYSkNCg0KSGVsbG8gSm9zZXBoLA0K DQpUaGF0J3MgYSBnb29kIGNhdGNoLiBTaW5jZSBtb2RpZnlpbmcgYWxsIGNvZGUgdGhhdCBhY2Nl c3NlcyB0aGUgcXVldWVfbG9jaw0KcG9pbnRlciBhbmQgdGhhdCBjYW4gcmFjZSB3aXRoIGJsa19j bGVhbnVwX3F1ZXVlKCkgd291bGQgYmUgdG9vIGN1bWJlcnNvbWUgSQ0Kc2VlIG9ubHkgb25lIHNv bHV0aW9uLCBuYW1lbHkgbWFraW5nIHRoZSByZXF1ZXN0IHF1ZXVlIGNncm91cCBhbmQgc3lzZnMN CmF0dHJpYnV0ZXMgaW52aXNpYmxlIGJlZm9yZSB0aGUgcXVldWVfbG9jayBwb2ludGVyIGlzIHJl c3RvcmVkLiBMZWF2aW5nIHRoZQ0KZGVidWdmcyBhdHRyaWJ1dGVzIHZpc2libGUgd2hpbGUgYmxr X2NsZWFudXBfcXVldWUoKSBpcyBpbiBwcm9ncmVzcyBzaG91bGQNCmJlIGZpbmUgaWYgdGhlIHJl cXVlc3QgcXVldWUgaW5pdGlhbGl6YXRpb24gY29kZSBpcyBtb2RpZmllZCBzdWNoIHRoYXQgaXQN Cm9ubHkgbW9kaWZpZXMgdGhlIHF1ZXVlX2xvY2sgcG9pbnRlciBmb3IgbGVnYWN5IHF1ZXVlcy4g SmFuLCBJIHRoaW5rIHNvbWUNCnRpbWUgYWdvIHlvdSBvYmplY3RlZCB3aGVuIEkgcHJvcG9zZWQg dG8gbW92ZSBjb2RlIGZyb20gX19ibGtfcmVsZWFzZV9xdWV1ZSgpDQppbnRvIGJsa19jbGVhbnVw X3F1ZXVlKCkuIFdvdWxkIHlvdSBiZSBmaW5lIHdpdGggYSBzbGlnaHRseSBkaWZmZXJlbnQNCmFw cHJvYWNoLCBuYW1lbHkgbWFraW5nIGJsb2NrIGNncm91cCBhbmQgc3lzZnMgYXR0cmlidXRlcyBp bnZpc2libGUgZWFybGllciwNCm5hbWVseSBmcm9tIGluc2lkZSBibGtfY2xlYW51cF9xdWV1ZSgp IGluc3RlYWQgb2YgZnJvbSBpbnNpZGUNCl9fYmxrX3JlbGVhc2VfcXVldWUoKT8NCg0KVGhhbmtz LA0KDQpCYXJ0Lg0KDQo=