From owner-svn-src-all@FreeBSD.ORG Thu May 21 16:43:28 2015 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id DC7CC7E4; Thu, 21 May 2015 16:43:27 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id CAD4A1671; Thu, 21 May 2015 16:43:27 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id t4LGhRCh001250; Thu, 21 May 2015 16:43:27 GMT (envelope-from jhb@FreeBSD.org) Received: (from jhb@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id t4LGhRAY001248; Thu, 21 May 2015 16:43:27 GMT (envelope-from jhb@FreeBSD.org) Message-Id: <201505211643.t4LGhRAY001248@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: jhb set sender to jhb@FreeBSD.org using -f From: John Baldwin Date: Thu, 21 May 2015 16:43:27 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r283250 - in head/sys: kern sys X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 May 2015 16:43:28 -0000 Author: jhb Date: Thu May 21 16:43:26 2015 New Revision: 283250 URL: https://svnweb.freebsd.org/changeset/base/283250 Log: Revert r282971. It depends on condvar consumers not destroying condvars until all threads sleeping on a condvar have resumed execution after being awakened. However, there are cases where that guarantee is very hard to provide. Modified: head/sys/kern/kern_condvar.c head/sys/sys/condvar.h Modified: head/sys/kern/kern_condvar.c ============================================================================== --- head/sys/kern/kern_condvar.c Thu May 21 15:38:43 2015 (r283249) +++ head/sys/kern/kern_condvar.c Thu May 21 16:43:26 2015 (r283250) @@ -122,7 +122,7 @@ _cv_wait(struct cv *cvp, struct lock_obj sleepq_lock(cvp); - atomic_add_int(&cvp->cv_waiters, 1); + cvp->cv_waiters++; if (lock == &Giant.lock_object) mtx_assert(&Giant, MA_OWNED); DROP_GIANT(); @@ -137,7 +137,6 @@ _cv_wait(struct cv *cvp, struct lock_obj sleepq_lock(cvp); } sleepq_wait(cvp, 0); - atomic_subtract_int(&cvp->cv_waiters, 1); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) @@ -185,7 +184,7 @@ _cv_wait_unlock(struct cv *cvp, struct l sleepq_lock(cvp); - atomic_add_int(&cvp->cv_waiters, 1); + cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); @@ -195,7 +194,6 @@ _cv_wait_unlock(struct cv *cvp, struct l if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); sleepq_wait(cvp, 0); - atomic_subtract_int(&cvp->cv_waiters, 1); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) @@ -242,7 +240,7 @@ _cv_wait_sig(struct cv *cvp, struct lock sleepq_lock(cvp); - atomic_add_int(&cvp->cv_waiters, 1); + cvp->cv_waiters++; if (lock == &Giant.lock_object) mtx_assert(&Giant, MA_OWNED); DROP_GIANT(); @@ -258,7 +256,6 @@ _cv_wait_sig(struct cv *cvp, struct lock sleepq_lock(cvp); } rval = sleepq_wait_sig(cvp, 0); - atomic_subtract_int(&cvp->cv_waiters, 1); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) @@ -310,7 +307,7 @@ _cv_timedwait_sbt(struct cv *cvp, struct sleepq_lock(cvp); - atomic_add_int(&cvp->cv_waiters, 1); + cvp->cv_waiters++; if (lock == &Giant.lock_object) mtx_assert(&Giant, MA_OWNED); DROP_GIANT(); @@ -326,7 +323,6 @@ _cv_timedwait_sbt(struct cv *cvp, struct sleepq_lock(cvp); } rval = sleepq_timedwait(cvp, 0); - atomic_subtract_int(&cvp->cv_waiters, 1); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) @@ -380,7 +376,7 @@ _cv_timedwait_sig_sbt(struct cv *cvp, st sleepq_lock(cvp); - atomic_add_int(&cvp->cv_waiters, 1); + cvp->cv_waiters++; if (lock == &Giant.lock_object) mtx_assert(&Giant, MA_OWNED); DROP_GIANT(); @@ -397,7 +393,6 @@ _cv_timedwait_sig_sbt(struct cv *cvp, st sleepq_lock(cvp); } rval = sleepq_timedwait_sig(cvp, 0); - atomic_subtract_int(&cvp->cv_waiters, 1); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) @@ -426,8 +421,10 @@ cv_signal(struct cv *cvp) wakeup_swapper = 0; sleepq_lock(cvp); - if (cvp->cv_waiters > 0) + if (cvp->cv_waiters > 0) { + cvp->cv_waiters--; wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0); + } sleepq_release(cvp); if (wakeup_swapper) kick_proc0(); @@ -450,8 +447,10 @@ cv_broadcastpri(struct cv *cvp, int pri) if (pri == -1) pri = 0; sleepq_lock(cvp); - if (cvp->cv_waiters > 0) + if (cvp->cv_waiters > 0) { + cvp->cv_waiters = 0; wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); + } sleepq_release(cvp); if (wakeup_swapper) kick_proc0(); Modified: head/sys/sys/condvar.h ============================================================================== --- head/sys/sys/condvar.h Thu May 21 15:38:43 2015 (r283249) +++ head/sys/sys/condvar.h Thu May 21 16:43:26 2015 (r283250) @@ -45,7 +45,7 @@ TAILQ_HEAD(cv_waitq, thread); */ struct cv { const char *cv_description; - volatile int cv_waiters; + int cv_waiters; }; #ifdef _KERNEL