From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp05.in.ibm.com (e28smtp05.in.ibm.com [122.248.162.5]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id B5C522C0294 for ; Tue, 11 Mar 2014 07:37:09 +1100 (EST) Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 11 Mar 2014 02:07:06 +0530 Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id AFBEAE003F for ; Tue, 11 Mar 2014 02:10:48 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s2AKb77V42991746 for ; Tue, 11 Mar 2014 02:07:07 +0530 Received: from d28av02.in.ibm.com (localhost [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s2AKb2PB012790 for ; Tue, 11 Mar 2014 02:07:03 +0530 From: "Srivatsa S. Bhat" Subject: [PATCH v3 18/52] x86, intel, uncore: Fix CPU hotplug callback registration To: paulus@samba.org, oleg@redhat.com, mingo@kernel.org, rjw@rjwysocki.net, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Date: Tue, 11 Mar 2014 02:06:57 +0530 Message-ID: <20140310203657.10746.98632.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> References: <20140310203312.10746.310.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: linux-arch@vger.kernel.org, ego@linux.vnet.ibm.com, walken@google.com, linux@arm.linux.org.uk, Arnaldo Carvalho de Melo , linux-pm@vger.kernel.org, Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Paul Mackerras , "Srivatsa S. Bhat" , "H. Peter Anvin" , tj@kernel.org, Thomas Gleixner , paulmck@linux.vnet.ibm.com, Ingo Molnar List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Instead, the correct and race-free way of performing the callback registration is: cpu_notifier_register_begin(); for_each_online_cpu(cpu) init_cpu(cpu); /* Note the use of the double underscored version of the API */ __register_cpu_notifier(&foobar_cpu_notifier); cpu_notifier_register_done(); Fix the uncore code in intel-x86 by using this latter form of callback registration. Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: x86@kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/x86/kernel/cpu/perf_event_intel_uncore.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c index c88f7f4..e90183d 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c +++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c @@ -3816,7 +3816,7 @@ static int __init uncore_cpu_init(void) if (ret) return ret; - get_online_cpus(); + cpu_notifier_register_begin(); for_each_online_cpu(cpu) { int i, phys_id = topology_physical_package_id(cpu); @@ -3835,9 +3835,9 @@ static int __init uncore_cpu_init(void) } on_each_cpu(uncore_cpu_setup, NULL, 1); - register_cpu_notifier(&uncore_cpu_nb); + __register_cpu_notifier(&uncore_cpu_nb); - put_online_cpus(); + cpu_notifier_register_done(); return 0; }