From patchwork Thu Feb 7 19:07:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 10801993 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 76A37746 for ; Thu, 7 Feb 2019 19:11:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6616E2CD35 for ; Thu, 7 Feb 2019 19:11:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 592C12E060; Thu, 7 Feb 2019 19:11:09 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E6B6A2CD35 for ; Thu, 7 Feb 2019 19:11:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727321AbfBGTJf (ORCPT ); Thu, 7 Feb 2019 14:09:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59906 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726791AbfBGTJe (ORCPT ); Thu, 7 Feb 2019 14:09:34 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DCCF488E52; Thu, 7 Feb 2019 19:09:33 +0000 (UTC) Received: from llong.com (dhcp-17-35.bos.redhat.com [10.18.17.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B1361693B; Thu, 7 Feb 2019 19:09:28 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, x86@kernel.org, Arnd Bergmann , Borislav Petkov , "H. Peter Anvin" , Davidlohr Bueso , Linus Torvalds , Andrew Morton , Tim Chen , Waiman Long Subject: [PATCH-tip 09/22] locking/rwsem: Enhance DEBUG_RWSEMS_WARN_ON() macro Date: Thu, 7 Feb 2019 14:07:13 -0500 Message-Id: <1549566446-27967-10-git-send-email-longman@redhat.com> In-Reply-To: <1549566446-27967-1-git-send-email-longman@redhat.com> References: <1549566446-27967-1-git-send-email-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 07 Feb 2019 19:09:34 +0000 (UTC) Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, the DEBUG_RWSEMS_WARN_ON() macro just dumps a stack trace when the rwsem isn't in the right state. It does not show the actual states of the rwsem. This may not be that helpful in the debugging process. Enhance the DEBUG_RWSEMS_WARN_ON() macro to also show the current content of the rwsem count and owner fields to give more information about what is wrong with the rwsem. Signed-off-by: Waiman Long --- kernel/locking/rwsem-xadd.h | 19 ++++++++++++------- kernel/locking/rwsem.c | 5 +++-- 2 files changed, 15 insertions(+), 9 deletions(-) diff --git a/kernel/locking/rwsem-xadd.h b/kernel/locking/rwsem-xadd.h index 77151c3..6d2478c 100644 --- a/kernel/locking/rwsem-xadd.h +++ b/kernel/locking/rwsem-xadd.h @@ -27,9 +27,13 @@ #define RWSEM_ANONYMOUSLY_OWNED (1UL << 1) #ifdef CONFIG_DEBUG_RWSEMS -# define DEBUG_RWSEMS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c) +# define DEBUG_RWSEMS_WARN_ON(c, sem) \ + WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\ + #c, atomic_long_read(&(sem)->count), \ + (long)((sem)->owner), (long)current, \ + list_empty(&(sem)->wait_list) ? "" : "not ") #else -# define DEBUG_RWSEMS_WARN_ON(c) +# define DEBUG_RWSEMS_WARN_ON(c, sem) #endif /* @@ -168,7 +172,7 @@ static inline void __down_read(struct rw_semaphore *sem) if (unlikely(atomic_long_inc_return_acquire(&sem->count) <= 0)) { rwsem_down_read_failed(sem); DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & - RWSEM_READER_OWNED)); + RWSEM_READER_OWNED), sem); } else { rwsem_set_reader_owned(sem); } @@ -180,7 +184,7 @@ static inline int __down_read_killable(struct rw_semaphore *sem) if (IS_ERR(rwsem_down_read_failed_killable(sem))) return -EINTR; DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & - RWSEM_READER_OWNED)); + RWSEM_READER_OWNED), sem); } else { rwsem_set_reader_owned(sem); } @@ -248,7 +252,8 @@ static inline void __up_read(struct rw_semaphore *sem) { long tmp; - DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED)); + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED), + sem); rwsem_clear_reader_owned(sem); tmp = atomic_long_dec_return_release(&sem->count); if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) @@ -260,7 +265,7 @@ static inline void __up_read(struct rw_semaphore *sem) */ static inline void __up_write(struct rw_semaphore *sem) { - DEBUG_RWSEMS_WARN_ON(sem->owner != current); + DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem); rwsem_clear_owner(sem); if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS, &sem->count) < 0)) @@ -281,7 +286,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem) * read-locked region is ok to be re-ordered into the * write side. As such, rely on RELEASE semantics. */ - DEBUG_RWSEMS_WARN_ON(sem->owner != current); + DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem); tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS, &sem->count); rwsem_set_reader_owned(sem); if (tmp < 0) diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c index 598fc7c..bdfca7c 100644 --- a/kernel/locking/rwsem.c +++ b/kernel/locking/rwsem.c @@ -17,7 +17,7 @@ #include "rwsem-xadd.h" #else #define __rwsem_set_reader_owned(a, b) -#define DEBUG_RWSEMS_WARN_ON(a) +#define DEBUG_RWSEMS_WARN_ON(a, b) #endif /* @@ -203,7 +203,8 @@ int __sched down_write_killable_nested(struct rw_semaphore *sem, int subclass) void up_read_non_owner(struct rw_semaphore *sem) { - DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED)); + DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED), + sem); __up_read(sem); }