From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751371AbdH1O44 (ORCPT ); Mon, 28 Aug 2017 10:56:56 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:34409 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751184AbdH1O4y (ORCPT ); Mon, 28 Aug 2017 10:56:54 -0400 From: Boqun Feng To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Gautham R Shenoy , Byungchul Park , Boqun Feng Subject: [RFC tip 1/5] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Date: Mon, 28 Aug 2017 22:56:53 +0800 Message-Id: <20170828145657.11292-2-boqun.feng@gmail.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170828145657.11292-1-boqun.feng@gmail.com> References: <20170828145657.11292-1-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As our chain cache doesn't differ read/write locks, so even we can detect a read-lock/lock-write deadlock in check_noncircular(), we can still be fooled if a read-lock/lock-read case(which is not a deadlock) comes first. So introduce this test case to test specific to the chain cache behavior on detecting recursive read lock related deadlocks. Signed-off-by: Boqun Feng --- lib/locking-selftest.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index 3c7151a6cd98..747a5379aeee 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -394,6 +394,49 @@ static void rwsem_ABBA1(void) MU(Y1); // should fail } +/* + * read_lock(A) + * spin_lock(B) + * spin_lock(B) + * write_lock(A) + * + * This test case is aimed at poking whether the chain cache prevents us from + * detecting a read-lock/lock-write deadlock: if the chain cache doesn't differ + * read/write locks, the following case may happen + * + * { read_lock(A)->lock(B) dependency exists } + * + * P0: + * lock(B); + * read_lock(A); + * + * { Not a deadlock, B -> A is added in the chain cache } + * + * P1: + * lock(B); + * write_lock(A); + * + * { B->A found in chain cache, not reported as a deadlock } + * + */ +static void rlock_chaincache_ABBA1(void) +{ + RL(X1); + L(Y1); + U(Y1); + RU(X1); + + L(Y1); + RL(X1); + RU(X1); + U(Y1); + + L(Y1); + WL(X1); + WU(X1); + U(Y1); // should fail +} + /* * read_lock(A) * spin_lock(B) @@ -2046,6 +2089,10 @@ void locking_selftest(void) pr_cont(" |"); dotest(rwsem_ABBA3, FAILURE, LOCKTYPE_RWSEM); + print_testname("chain cached mixed R-L/L-W ABBA"); + pr_cont(" |"); + dotest(rlock_chaincache_ABBA1, FAILURE, LOCKTYPE_RWLOCK); + printk(" --------------------------------------------------------------------------\n"); /* -- 2.14.1