From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbaBNH5k (ORCPT ); Fri, 14 Feb 2014 02:57:40 -0500 Received: from e28smtp05.in.ibm.com ([122.248.162.5]:38960 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752010AbaBNH5g (ORCPT ); Fri, 14 Feb 2014 02:57:36 -0500 From: "Srivatsa S. Bhat" Subject: [PATCH v2 13/52] sparc, sysfs: Fix CPU hotplug callback registration To: paulus@samba.org, oleg@redhat.com, mingo@kernel.org, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, "David S. Miller" , Ingo Molnar , sparclinux@vger.kernel.org, "Srivatsa S. Bhat" Date: Fri, 14 Feb 2014 13:22:05 +0530 Message-ID: <20140214075204.22701.72009.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> References: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14021407-8256-0000-0000-00000B767704 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 sysfs code in sparc by using this latter form of callback registration. Cc: "David S. Miller" Cc: Ingo Molnar Cc: sparclinux@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/sparc/kernel/sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/sysfs.c b/arch/sparc/kernel/sysfs.c index c21c673..a364000 100644 --- a/arch/sparc/kernel/sysfs.c +++ b/arch/sparc/kernel/sysfs.c @@ -300,7 +300,7 @@ static int __init topology_init(void) check_mmu_stats(); - register_cpu_notifier(&sysfs_cpu_nb); + cpu_notifier_register_begin(); for_each_possible_cpu(cpu) { struct cpu *c = &per_cpu(cpu_devices, cpu); @@ -310,6 +310,10 @@ static int __init topology_init(void) register_cpu_online(cpu); } + __register_cpu_notifier(&sysfs_cpu_nb); + + cpu_notifier_register_done(); + return 0; } From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v2 13/52] sparc, sysfs: Fix CPU hotplug callback registration Date: Fri, 14 Feb 2014 13:22:05 +0530 Message-ID: <20140214075204.22701.72009.stgit@srivatsabhat.in.ibm.com> References: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: paulus@samba.org, oleg@redhat.com, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, "David S. Miller" , Ingo Molnar , sparclinux@vger.kernel.org"Srivatsa S. Bhat" List-Id: linux-arch.vger.kernel.org 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 sysfs code in sparc by using this latter form of callback registration. Cc: "David S. Miller" Cc: Ingo Molnar Cc: sparclinux@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/sparc/kernel/sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/sysfs.c b/arch/sparc/kernel/sysfs.c index c21c673..a364000 100644 --- a/arch/sparc/kernel/sysfs.c +++ b/arch/sparc/kernel/sysfs.c @@ -300,7 +300,7 @@ static int __init topology_init(void) check_mmu_stats(); - register_cpu_notifier(&sysfs_cpu_nb); + cpu_notifier_register_begin(); for_each_possible_cpu(cpu) { struct cpu *c = &per_cpu(cpu_devices, cpu); @@ -310,6 +310,10 @@ static int __init topology_init(void) register_cpu_online(cpu); } + __register_cpu_notifier(&sysfs_cpu_nb); + + cpu_notifier_register_done(); + return 0; } From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp05.in.ibm.com ([122.248.162.5]:38959 "EHLO e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752620AbaBNH5j (ORCPT ); Fri, 14 Feb 2014 02:57:39 -0500 Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 14 Feb 2014 13:27:34 +0530 From: "Srivatsa S. Bhat" Subject: [PATCH v2 13/52] sparc, sysfs: Fix CPU hotplug callback registration Date: Fri, 14 Feb 2014 13:22:05 +0530 Message-ID: <20140214075204.22701.72009.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> References: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: paulus@samba.org, oleg@redhat.com, mingo@kernel.org, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, "David S. Miller" , sparclinux@vger.kernel.org"Srivatsa S. Bhat" Message-ID: <20140214075205.dI_JpBbMQGgDURSTr5gT8Ys8YIxFQLf-7Ohw9Ptsz0s@z> 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 sysfs code in sparc by using this latter form of callback registration. Cc: "David S. Miller" Cc: Ingo Molnar Cc: sparclinux@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/sparc/kernel/sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/sysfs.c b/arch/sparc/kernel/sysfs.c index c21c673..a364000 100644 --- a/arch/sparc/kernel/sysfs.c +++ b/arch/sparc/kernel/sysfs.c @@ -300,7 +300,7 @@ static int __init topology_init(void) check_mmu_stats(); - register_cpu_notifier(&sysfs_cpu_nb); + cpu_notifier_register_begin(); for_each_possible_cpu(cpu) { struct cpu *c = &per_cpu(cpu_devices, cpu); @@ -310,6 +310,10 @@ static int __init topology_init(void) register_cpu_online(cpu); } + __register_cpu_notifier(&sysfs_cpu_nb); + + cpu_notifier_register_done(); + return 0; } From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Date: Fri, 14 Feb 2014 07:57:58 +0000 Subject: [PATCH v2 13/52] sparc, sysfs: Fix CPU hotplug callback registration Message-Id: <20140214075204.22701.72009.stgit@srivatsabhat.in.ibm.com> List-Id: References: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20140214074750.22701.47330.stgit@srivatsabhat.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: paulus@samba.org, oleg@redhat.com, rusty@rustcorp.com.au, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org Cc: paulmck@linux.vnet.ibm.com, tj@kernel.org, walken@google.com, ego@linux.vnet.ibm.com, linux@arm.linux.org.uk, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, "David S. Miller" , Ingo Molnar , sparclinux@vger.kernel.org"Srivatsa S. Bhat" 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 sysfs code in sparc by using this latter form of callback registration. Cc: "David S. Miller" Cc: Ingo Molnar Cc: sparclinux@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- arch/sparc/kernel/sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/sysfs.c b/arch/sparc/kernel/sysfs.c index c21c673..a364000 100644 --- a/arch/sparc/kernel/sysfs.c +++ b/arch/sparc/kernel/sysfs.c @@ -300,7 +300,7 @@ static int __init topology_init(void) check_mmu_stats(); - register_cpu_notifier(&sysfs_cpu_nb); + cpu_notifier_register_begin(); for_each_possible_cpu(cpu) { struct cpu *c = &per_cpu(cpu_devices, cpu); @@ -310,6 +310,10 @@ static int __init topology_init(void) register_cpu_online(cpu); } + __register_cpu_notifier(&sysfs_cpu_nb); + + cpu_notifier_register_done(); + return 0; }