From owner-svn-src-head@freebsd.org Thu Dec 5 13:43:45 2019 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 864DE1CA10B; Thu, 5 Dec 2019 13:43:45 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47TH4K30gTz4DJv; Thu, 5 Dec 2019 13:43:45 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4AB4919C45; Thu, 5 Dec 2019 13:43:45 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id xB5Dhjie090823; Thu, 5 Dec 2019 13:43:45 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id xB5Dhj4G090822; Thu, 5 Dec 2019 13:43:45 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201912051343.xB5Dhj4G090822@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Thu, 5 Dec 2019 13:43:45 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r355416 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 355416 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Dec 2019 13:43:45 -0000 Author: mjg Date: Thu Dec 5 13:43:44 2019 New Revision: 355416 URL: https://svnweb.freebsd.org/changeset/base/355416 Log: sx: check for SX_LOCK_SHARED | SX_LOCK_WRITE_SPINNER when exclusive-locking First, this removes a spurious difference compared to rw locks. More importantly though this avoids a trip through sleepq code if the lock happens to be caught in this state. Modified: head/sys/kern/kern_sx.c Modified: head/sys/kern/kern_sx.c ============================================================================== --- head/sys/kern/kern_sx.c Thu Dec 5 13:41:22 2019 (r355415) +++ head/sys/kern/kern_sx.c Thu Dec 5 13:43:44 2019 (r355416) @@ -661,6 +661,12 @@ _sx_xlock_hard(struct sx *sx, uintptr_t x, int opts LO lda.spin_cnt++; #endif #ifdef ADAPTIVE_SX + if (x == (SX_LOCK_SHARED | SX_LOCK_WRITE_SPINNER)) { + if (atomic_fcmpset_acq_ptr(&sx->sx_lock, &x, tid)) + break; + continue; + } + /* * If the lock is write locked and the owner is * running on another CPU, spin until the owner stops