From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965146AbcDLPDc (ORCPT ); Tue, 12 Apr 2016 11:03:32 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:39148 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965046AbcDLPD0 (ORCPT ); Tue, 12 Apr 2016 11:03:26 -0400 X-IBM-Helo: d03dlp02.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, Boqun Feng , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 5/6] rcu: Remove superfluous versions of rcu_read_lock_sched_held() Date: Tue, 12 Apr 2016 08:02:21 -0700 Message-Id: <1460473342-20836-5-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20160412150157.GA19367@linux.vnet.ibm.com> References: <20160412150157.GA19367@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16041215-0025-0000-0000-00002CD81372 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Boqun Feng Currently, we have four versions of rcu_read_lock_sched_held(), depending on the combined choices on PREEMPT_COUNT and DEBUG_LOCK_ALLOC. However, there is an existing function preemptible() that already distinguishes between the PREEMPT_COUNT=y and PREEMPT_COUNT=n cases, and allows these four implementations to be consolidated down to two. This commit therefore uses preemptible() to achieve this consolidation. Note that there could be a small performance regression in the case of CONFIG_DEBUG_LOCK_ALLOC=y && PREEMPT_COUNT=n. However, given the overhead associated with CONFIG_DEBUG_LOCK_ALLOC=y, this should be down in the noise. Signed-off-by: Boqun Feng Signed-off-by: Paul E. McKenney --- include/linux/rcupdate.h | 17 +---------------- kernel/rcu/update.c | 4 ++-- 2 files changed, 3 insertions(+), 18 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 45de591657a6..5f1533e3d032 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -508,14 +508,7 @@ int rcu_read_lock_bh_held(void); * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side * critical section unless it can prove otherwise. */ -#ifdef CONFIG_PREEMPT_COUNT int rcu_read_lock_sched_held(void); -#else /* #ifdef CONFIG_PREEMPT_COUNT */ -static inline int rcu_read_lock_sched_held(void) -{ - return 1; -} -#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */ #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ @@ -532,18 +525,10 @@ static inline int rcu_read_lock_bh_held(void) return 1; } -#ifdef CONFIG_PREEMPT_COUNT static inline int rcu_read_lock_sched_held(void) { - return preempt_count() != 0 || irqs_disabled(); + return !preemptible(); } -#else /* #ifdef CONFIG_PREEMPT_COUNT */ -static inline int rcu_read_lock_sched_held(void) -{ - return 1; -} -#endif /* #else #ifdef CONFIG_PREEMPT_COUNT */ - #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ #ifdef CONFIG_PROVE_RCU diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index ca828b41c938..3ccdc8eebc5a 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -67,7 +67,7 @@ static int rcu_normal_after_boot; module_param(rcu_normal_after_boot, int, 0); #endif /* #ifndef CONFIG_TINY_RCU */ -#if defined(CONFIG_DEBUG_LOCK_ALLOC) && defined(CONFIG_PREEMPT_COUNT) +#ifdef CONFIG_DEBUG_LOCK_ALLOC /** * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? * @@ -111,7 +111,7 @@ int rcu_read_lock_sched_held(void) return 0; if (debug_locks) lockdep_opinion = lock_is_held(&rcu_sched_lock_map); - return lockdep_opinion || preempt_count() != 0 || irqs_disabled(); + return lockdep_opinion || !preemptible(); } EXPORT_SYMBOL(rcu_read_lock_sched_held); #endif -- 2.5.2