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Fri, 30 Nov 2018 17:34:20 +0800 From: "Liu,Qi(ACU-T1)" To: 'Peter Zijlstra' , Waiman Long CC: Will Deacon , Yongji Xie , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "Xie,Yongji" , "Zhang,Yu(ACU-T1)" , "Yuan,Linsi" , "Ni,Xun" , "Li,Lin(ACU-T1)" , Davidlohr Bueso Subject: =?gb2312?B?tPC4tDogW1JGQ10gbG9ja2luZy9yd3NlbTogQXZvaWQgaXNzdWluZyB3YWtl?= =?gb2312?Q?up_before_setting_the_reader_waiter_to_nil?= Thread-Topic: [RFC] locking/rwsem: Avoid issuing wakeup before setting the reader waiter to nil Thread-Index: AQHUh+I/IzQW+DeqbkO+lYev54G5OKVmNH4AgAAkKgCAAAxugIAAD5yAgAAG5QCAAAuWAIAABQ8AgAABQICAAADZgIAAOyMAgAFEwZA= Date: Fri, 30 Nov 2018 09:34:19 +0000 Message-ID: References: <1543495830-2644-1-git-send-email-xieyongji@baidu.com> <20181129131232.GN2131@hirez.programming.kicks-ass.net> <5598cd71-c3c8-d6ef-eb30-777cf901a2ef@redhat.com> <20181129160627.GU2131@hirez.programming.kicks-ass.net> <8cc45695-b325-a219-8b46-d5da6ddfdd63@redhat.com> <20181129172700.GA11632@hirez.programming.kicks-ass.net> <20181129180828.GA11650@hirez.programming.kicks-ass.net> <729ceddb-dd9a-ec2a-f74e-03fa4d7e65e8@redhat.com> <20181129183103.GA4952@arm.com> <20181129220544.GE11632@hirez.programming.kicks-ass.net> In-Reply-To: <20181129220544.GE11632@hirez.programming.kicks-ass.net> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.24.154.236] x-baidu-bdmsfe-datecheck: 1_BC-Mail-EX02_2018-11-30 17:34:20:210 x-baidu-bdmsfe-viruscheck: BC-Mail-EX02_GRAY_Inside_WithoutAtta_2018-11-30 17:34:20:179 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: base64 MIME-Version: 1.0 X-Baidu-BdMsfe-DateCheck: 1_M1-MAIL-EX14_2018-11-30 17:34:20:435 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org SXMgdGhlcmUgYSBzZW1hbnRpYyBkaXZlcmdlbmNlIGJldHdlZW4geDg2IGluc3RydWN0aW9uICJM T0NLIGNtcHhjaGciIGFuZCB0aGUgbWFjcm8gY21weGNoZyBkZWZpbmVkIGluIGxpbnV4IGtlcm5l bD8gVGhlIGZvcm1lciBndWFyYW50ZWUgZnVsbCBiYXJyaWVyIGluIGFueSBjYXNlLCBhbmQgdGhl IGxhdHRlciBvbmx5IGltcGx5IGJhcnJpZXIgaW4gY2FzZSBvZiBzdWNjZXNzPw0KU28sIHdlIHVz ZSAJDQogICAgc21wX21iX19iZWZvcmVfYXRvbWljKCkNCgljbXB4Y2hnX3JlbGF4ZWQoKSAgLy8g bm8gYmFycmllcg0KdG8gZ2V0IHJpZCBvZiB0aGUgcmVkdW5kYW50IGJhcnJpZXINCiAgIHNtcF9t Yl9fYmVmb3JlX2F0b21pYygpDQogICBjbXB4Y2hnKCkgICAgICAgICAgLy8gaW1wbHkgYSByZWR1 bmRhbnQgYmFycmllciB3aGVuIHN1Y2Nlc3NpbmcgIA0KICAgIA0KLS0tLS3Tyrz+1K28/i0tLS0t DQq3orz+yMs6IFBldGVyIFppamxzdHJhIFttYWlsdG86cGV0ZXJ6QGluZnJhZGVhZC5vcmddIA0K t6LLzcqxvOQ6IDIwMTjE6jEx1MIzMMjVIDY6MDYNCsrVvP7IyzogV2FpbWFuIExvbmcgPGxvbmdt YW5AcmVkaGF0LmNvbT4NCrOty806IFdpbGwgRGVhY29uIDx3aWxsLmRlYWNvbkBhcm0uY29tPjsg WW9uZ2ppIFhpZSA8ZWxvaGltZXNAZ21haWwuY29tPjsgbWluZ29AcmVkaGF0LmNvbTsgbGludXgt a2VybmVsQHZnZXIua2VybmVsLm9yZzsgWGllLFlvbmdqaSA8eGlleW9uZ2ppQGJhaWR1LmNvbT47 IFpoYW5nLFl1KEFDVS1UMSkgPHpoYW5neXUzMUBiYWlkdS5jb20+OyBMaXUsUWkoQUNVLVQxKSA8 bGl1cWkxNkBiYWlkdS5jb20+OyBZdWFuLExpbnNpIDx5dWFubGluc2kwMUBiYWlkdS5jb20+OyBO aSxYdW4gPG5peHVuQGJhaWR1LmNvbT47IExpLExpbihBQ1UtVDEpIDxsaWxpbjI0QGJhaWR1LmNv bT47IERhdmlkbG9ociBCdWVzbyA8ZGF2ZUBzdGdvbGFicy5uZXQ+DQrW98ziOiBSZTogW1JGQ10g bG9ja2luZy9yd3NlbTogQXZvaWQgaXNzdWluZyB3YWtldXAgYmVmb3JlIHNldHRpbmcgdGhlIHJl YWRlciB3YWl0ZXIgdG8gbmlsDQoNCk9uIFRodSwgTm92IDI5LCAyMDE4IGF0IDAxOjM0OjA1UE0g LTA1MDAsIFdhaW1hbiBMb25nIHdyb3RlOg0KDQo+IFRoYXQgd2lsbCBjZXJ0YWlubHkgd29yayBm b3IgeDg2LiBIb3dldmVyLCBJIGFtIG5vdCBzdXJlIGlmIHRoYXQgd2lsbCANCj4gYmUgb3B0aW1h bCBmb3IgYXJtIGFuZCBwb3dlcnBjLg0KDQoJc21wX21iX19iZWZvcmVfYXRvbWljKCkNCgljbXB4 Y2hnX3JlbGF4ZWQoKQ0KDQp3b3Jrcy4gQWxzbyBzZWUgcHZfa2lja19ub2RlKCkncyBjb21taXQ6 DQoNCiAgMzRkNTRmM2Q2OTE3ICgibG9ja2luZy9wdnFzcGlubG9jazogUmVsYXggY21weGNoZydz IHRvIGltcHJvdmUgcGVyZm9ybWFuY2Ugb24gc29tZSBhcmNoaXRlY3R1cmVzIikNCg0KeW91IG1p Z2h0IGtub3cgdGhlIGF1dGhvciBvZiB0aGF0IDotKQ0K