From owner-dev-commits-src-main@freebsd.org Tue Jan 19 12:21:42 2021 Return-Path: Delivered-To: dev-commits-src-main@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 D5C064F2AC6; Tue, 19 Jan 2021 12:21:42 +0000 (UTC) (envelope-from git@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) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DKnny5mBjz3Mkg; Tue, 19 Jan 2021 12:21:42 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id B8DD52654A; Tue, 19 Jan 2021 12:21:42 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 10JCLgIZ058528; Tue, 19 Jan 2021 12:21:42 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 10JCLgWm058527; Tue, 19 Jan 2021 12:21:42 GMT (envelope-from git) Date: Tue, 19 Jan 2021 12:21:42 GMT Message-Id: <202101191221.10JCLgWm058527@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mateusz Guzik Subject: git: 38baca17e01e - main - lockmgr: fix upgrade MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mjg X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 38baca17e01e138dc9c7211c0f6cb4ba74b14449 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-main@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for the main branch of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Jan 2021 12:21:42 -0000 The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=38baca17e01e138dc9c7211c0f6cb4ba74b14449 commit 38baca17e01e138dc9c7211c0f6cb4ba74b14449 Author: Mateusz Guzik AuthorDate: 2021-01-07 06:45:49 +0000 Commit: Mateusz Guzik CommitDate: 2021-01-19 12:21:38 +0000 lockmgr: fix upgrade TRYUPGRADE requests kept failing when they should not have due to wrong macro used to count readers. Fixes: f6b091fbbd77cbb0 ("lockmgr: rewrite upgrade to stop always dropping the lock") Noted by: asomers Differential Revision: https://reviews.freebsd.org/D27947 --- sys/kern/kern_lock.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c index 98c6cafde702..091abcda2a1e 100644 --- a/sys/kern/kern_lock.c +++ b/sys/kern/kern_lock.c @@ -984,17 +984,19 @@ lockmgr_upgrade(struct lock *lk, u_int flags, struct lock_object *ilk, op = flags & LK_TYPE_MASK; v = lockmgr_read_value(lk); for (;;) { - if (LK_SHARERS_LOCK(v) > 1) { + if (LK_SHARERS(v) > 1) { if (op == LK_TRYUPGRADE) { LOCK_LOG2(lk, "%s: %p failed the nowait upgrade", __func__, lk); error = EBUSY; goto out; } - if (lockmgr_sunlock_try(lk, &v)) { + if (atomic_fcmpset_rel_ptr(&lk->lk_lock, &v, + v - LK_ONE_SHARER)) { lockmgr_note_shared_release(lk, file, line); goto out_xlock; } + continue; } MPASS((v & ~LK_ALL_WAITERS) == LK_SHARERS_LOCK(1));