From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751324AbdEBQYZ (ORCPT ); Tue, 2 May 2017 12:24:25 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:36921 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751199AbdEBQYX (ORCPT ); Tue, 2 May 2017 12:24:23 -0400 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, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" , Linus Torvalds Subject: [PATCH tip/core/rcu 1/3] rcu: Open-code the rcu_cblist_empty() function Date: Tue, 2 May 2017 09:24:13 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170502162114.GA12193@linux.vnet.ibm.com> References: <20170502162114.GA12193@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17050216-0036-0000-0000-000001F755DB X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007012; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000208; SDB=6.00855251; UDB=6.00423254; IPR=6.00634413; BA=6.00005322; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015271; XFM=3.00000014; UTC=2017-05-02 16:24:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17050216-0037-0000-0000-000040242EFC Message-Id: <1493742255-13222-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-02_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705020092 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Because the rcu_cblist_empty() just samples the ->head pointer, and because the rcu_cblist structure is quite straightforward, it makes sense to open-code rcu_cblist_empty(p) as !p->head, cutting out a level of indirection. This commit makes this change. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Linus Torvalds --- kernel/rcu/rcu_segcblist.h | 8 +------- kernel/rcu/tree.c | 9 ++++----- kernel/rcu/tree_plugin.h | 4 ++-- 3 files changed, 7 insertions(+), 14 deletions(-) diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h index 86bc1101b806..7d18d41f0116 100644 --- a/kernel/rcu/rcu_segcblist.h +++ b/kernel/rcu/rcu_segcblist.h @@ -22,12 +22,6 @@ #include -/* Is simple callback list empty? */ -static inline bool rcu_cblist_empty(struct rcu_cblist *rclp) -{ - return !rclp->head; -} - /* Return number of callbacks in simple callback list. */ static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp) { @@ -66,7 +60,7 @@ static inline struct rcu_head *rcu_cblist_head(struct rcu_cblist *rclp) */ static inline struct rcu_head **rcu_cblist_tail(struct rcu_cblist *rclp) { - WARN_ON_ONCE(rcu_cblist_empty(rclp)); + WARN_ON_ONCE(!rclp->head); return rclp->tail; } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 91fff49d5869..35152414760d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2647,9 +2647,9 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags) /* First adopt the ready-to-invoke callbacks, then the done ones. */ rcu_segcblist_insert_done_cbs(&rdp->cblist, &rsp->orphan_done); - WARN_ON_ONCE(!rcu_cblist_empty(&rsp->orphan_done)); + WARN_ON_ONCE(rsp->orphan_done.head); rcu_segcblist_insert_pend_cbs(&rdp->cblist, &rsp->orphan_pend); - WARN_ON_ONCE(!rcu_cblist_empty(&rsp->orphan_pend)); + WARN_ON_ONCE(rsp->orphan_pend.head); WARN_ON_ONCE(rcu_segcblist_empty(&rdp->cblist) != !rcu_segcblist_n_cbs(&rdp->cblist)); } @@ -2800,9 +2800,8 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) local_irq_save(flags); count = -rcu_cblist_n_cbs(&rcl); - trace_rcu_batch_end(rsp->name, count, !rcu_cblist_empty(&rcl), - need_resched(), is_idle_task(current), - rcu_is_callbacks_kthread()); + trace_rcu_batch_end(rsp->name, count, !!rcl.head, need_resched(), + is_idle_task(current), rcu_is_callbacks_kthread()); /* Update counts and requeue any remaining callbacks. */ rcu_segcblist_insert_done_cbs(&rdp->cblist, &rcl); diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 7f1d677a2a25..6b4b1f8a272d 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1942,12 +1942,12 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, return false; /* First, enqueue the donelist, if any. This preserves CB ordering. */ - if (!rcu_cblist_empty(&rsp->orphan_done)) { + if (rsp->orphan_done.head) { __call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_done), rcu_cblist_tail(&rsp->orphan_done), ql, qll, flags); } - if (!rcu_cblist_empty(&rsp->orphan_pend)) { + if (rsp->orphan_pend.head) { __call_rcu_nocb_enqueue(rdp, rcu_cblist_head(&rsp->orphan_pend), rcu_cblist_tail(&rsp->orphan_pend), ql, qll, flags); -- 2.5.2