From patchwork Thu Aug 30 18:56:15 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 11105 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id 6A01923F27 for ; Thu, 30 Aug 2012 21:43:44 +0000 (UTC) Received: from mail-iy0-f180.google.com (mail-iy0-f180.google.com [209.85.210.180]) by fiordland.canonical.com (Postfix) with ESMTP id 9A54AA192F8 for ; Thu, 30 Aug 2012 21:43:07 +0000 (UTC) Received: by mail-iy0-f180.google.com with SMTP id j25so3726599iaf.11 for ; Thu, 30 Aug 2012 14:43:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-forwarded-to:x-forwarded-for:delivered-to:received-spf:from:to:cc :subject:date:message-id:x-mailer:in-reply-to:references :x-content-scanned:x-cbid:x-gm-message-state; bh=53WyBlUc1OAYzraLvShdXr7BNevYR1v/SyxTlvZUAhY=; b=ENEfS6xQNJ0//Ms1uZe+FZKYH4bdmKrwLHS9MoYHgdV6CpfqnfrX8MdzGD+eYfubUM jVAk6XeH5YDLANflRs0j2UvSPqpkKEssw0Nm6qdsj8MUVrHTLB1epYo39R5kTQf3De6N /3CFJ/eolle791vPR9AFqG54dbjU9mB6Yryz1d0jx5fPdUy5YYNOqW43sKIn5ue3DikY Nd8XWTm9mT8O6bKeVGXxk+eez2EVz1hS8ov3I9l1ZmJ/1YeZREEEXa7EsLAbCVEgc+nv VGSEtMFKYc8d5UiNZhJllkRk4x7hXXB3CzD7USkbnJMpeXrbqioZSa2X9UnXEJaptqQP 2UMA== Received: by 10.50.237.41 with SMTP id uz9mr2427237igc.43.1346363023734; Thu, 30 Aug 2012 14:43:43 -0700 (PDT) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.50.184.232 with SMTP id ex8csp32868igc; Thu, 30 Aug 2012 14:43:43 -0700 (PDT) Received: by 10.60.169.110 with SMTP id ad14mr6098870oec.34.1346363023303; Thu, 30 Aug 2012 14:43:43 -0700 (PDT) Received: from e35.co.us.ibm.com (e35.co.us.ibm.com. [32.97.110.153]) by mx.google.com with ESMTPS id hm7si3564597obc.50.2012.08.30.14.43.43 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 30 Aug 2012 14:43:43 -0700 (PDT) Received-SPF: pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.110.153 as permitted sender) client-ip=32.97.110.153; Authentication-Results: mx.google.com; spf=pass (google.com: domain of paulmck@linux.vnet.ibm.com designates 32.97.110.153 as permitted sender) smtp.mail=paulmck@linux.vnet.ibm.com Received: from /spool/local by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 30 Aug 2012 15:43:42 -0600 Received: from d03dlp03.boulder.ibm.com (9.17.202.179) by e35.co.us.ibm.com (192.168.1.135) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Thu, 30 Aug 2012 15:43:39 -0600 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 3FB6819D805C; Thu, 30 Aug 2012 15:43:39 -0600 (MDT) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7ULhdll161422; Thu, 30 Aug 2012 15:43:39 -0600 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7ULhYhG026553; Thu, 30 Aug 2012 15:43:35 -0600 Received: from paulmck-ThinkPad-W500 (sig-9-65-153-225.mts.ibm.com [9.65.153.225]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q7ULhXOB026417; Thu, 30 Aug 2012 15:43:33 -0600 Received: by paulmck-ThinkPad-W500 (Postfix, from userid 1000) id 9006DE4D88; Thu, 30 Aug 2012 11:56:30 -0700 (PDT) From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 02/15] rcu: Pull TINY_RCU dyntick-idle tracing into non-idle region Date: Thu, 30 Aug 2012 11:56:15 -0700 Message-Id: <1346352988-32444-2-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1346352988-32444-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120830185607.GA32148@linux.vnet.ibm.com> <1346352988-32444-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12083021-6148-0000-0000-000009178972 X-Gm-Message-State: ALoCoQlZHvt4mjdBSRecg4TAI5d3a8m/A2bRHhO+GkhVAB/btj9kDhBOWnrilSfKstTxMHwlxWrk From: "Paul E. McKenney" Because TINY_RCU's idle detection keys directly off of the nesting level, rather than from a separate variable as in TREE_RCU, the TINY_RCU dyntick-idle tracing on transition to idle must happen before the change to the nesting level. This commit therefore makes this change by passing the desired new value (rather than the old value) of the nesting level in to rcu_idle_enter_common(). [ paulmck: Add fix for wrong-variable bug spotted by Michael Wang . ] Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutiny.c | 31 ++++++++++++++++--------------- 1 files changed, 16 insertions(+), 15 deletions(-) diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 547b1fe..e4163c5 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -56,24 +56,27 @@ static void __call_rcu(struct rcu_head *head, static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE; /* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ -static void rcu_idle_enter_common(long long oldval) +static void rcu_idle_enter_common(long long newval) { - if (rcu_dynticks_nesting) { + if (newval) { RCU_TRACE(trace_rcu_dyntick("--=", - oldval, rcu_dynticks_nesting)); + rcu_dynticks_nesting, newval)); + rcu_dynticks_nesting = newval; return; } - RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting)); + RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval)); if (!is_idle_task(current)) { struct task_struct *idle = idle_task(smp_processor_id()); RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", - oldval, rcu_dynticks_nesting)); + rcu_dynticks_nesting, newval)); ftrace_dump(DUMP_ALL); WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s", current->pid, current->comm, idle->pid, idle->comm); /* must be idle task! */ } + barrier(); + rcu_dynticks_nesting = newval; rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ } @@ -84,17 +87,16 @@ static void rcu_idle_enter_common(long long oldval) void rcu_idle_enter(void) { unsigned long flags; - long long oldval; + long long newval; local_irq_save(flags); - oldval = rcu_dynticks_nesting; WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0); if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) - rcu_dynticks_nesting = 0; + newval = 0; else - rcu_dynticks_nesting -= DYNTICK_TASK_NEST_VALUE; - rcu_idle_enter_common(oldval); + newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE; + rcu_idle_enter_common(newval); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(rcu_idle_enter); @@ -105,13 +107,12 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter); void rcu_irq_exit(void) { unsigned long flags; - long long oldval; + long long newval; local_irq_save(flags); - oldval = rcu_dynticks_nesting; - rcu_dynticks_nesting--; - WARN_ON_ONCE(rcu_dynticks_nesting < 0); - rcu_idle_enter_common(oldval); + newval = rcu_dynticks_nesting - 1; + WARN_ON_ONCE(newval < 0); + rcu_idle_enter_common(newval); local_irq_restore(flags); }