From owner-svn-src-all@freebsd.org Tue Sep 15 22:16:21 2015 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E501B9C2C84; Tue, 15 Sep 2015 22:16:21 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from repo.freebsd.org (repo.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 D5C1A10C3; Tue, 15 Sep 2015 22:16:21 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.70]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id t8FMGLGx023520; Tue, 15 Sep 2015 22:16:21 GMT (envelope-from jhb@FreeBSD.org) Received: (from jhb@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id t8FMGL74023519; Tue, 15 Sep 2015 22:16:21 GMT (envelope-from jhb@FreeBSD.org) Message-Id: <201509152216.t8FMGL74023519@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: jhb set sender to jhb@FreeBSD.org using -f From: John Baldwin Date: Tue, 15 Sep 2015 22:16:21 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r287833 - head/sys/kern 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: Tue, 15 Sep 2015 22:16:22 -0000 Author: jhb Date: Tue Sep 15 22:16:21 2015 New Revision: 287833 URL: https://svnweb.freebsd.org/changeset/base/287833 Log: Threads holding a read lock of a sleepable rm lock are not permitted to sleep. The rmlock implementation enforces this by disabling sleeping when a read lock is acquired. To simplify the implementation, sleeping is disabled for most of the duration of rm_rlock. However, it doesn't need to be disabled until the lock is acquired. If a sleepable rm lock is contested, then rm_rlock may need to acquire the backing sx lock. This tripped the overly-broad assertion. Fix by relaxing the assertion around the call to sx_xlock(). Reported by: mjg Reviewed by: kib, mjg MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D3324 Modified: head/sys/kern/kern_rmlock.c Modified: head/sys/kern/kern_rmlock.c ============================================================================== --- head/sys/kern/kern_rmlock.c Tue Sep 15 21:16:45 2015 (r287832) +++ head/sys/kern/kern_rmlock.c Tue Sep 15 22:16:21 2015 (r287833) @@ -407,9 +407,11 @@ _rm_rlock_hard(struct rmlock *rm, struct return (0); } } else { - if (rm->lock_object.lo_flags & LO_SLEEPABLE) + if (rm->lock_object.lo_flags & LO_SLEEPABLE) { + THREAD_SLEEPING_OK(); sx_xlock(&rm->rm_lock_sx); - else + THREAD_NO_SLEEPING(); + } else mtx_lock(&rm->rm_lock_mtx); }