From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753136AbaBNICn (ORCPT ); Fri, 14 Feb 2014 03:02:43 -0500 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:48699 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbaBNICk (ORCPT ); Fri, 14 Feb 2014 03:02:40 -0500 From: "Srivatsa S. Bhat" Subject: [PATCH v2 35/52] scsi, fcoe: 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, Robert Love , "James E.J. Bottomley" , Ingo Molnar , fcoe-devel@open-fcoe.org, linux-scsi@vger.kernel.org, "Srivatsa S. Bhat" Date: Fri, 14 Feb 2014 13:27:05 +0530 Message-ID: <20140214075704.22701.27489.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: 14021408-6102-0000-0000-000004F22F13 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 fcoe code in scsi by using this latter form of callback registration. Cc: Robert Love Cc: "James E.J. Bottomley" Cc: Ingo Molnar Cc: fcoe-devel@open-fcoe.org Cc: linux-scsi@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- drivers/scsi/fcoe/fcoe.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index f317000..d5e105b 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -2633,14 +2633,18 @@ static int __init fcoe_init(void) skb_queue_head_init(&p->fcoe_rx_list); } + cpu_notifier_register_begin(); + for_each_online_cpu(cpu) fcoe_percpu_thread_create(cpu); /* Initialize per CPU interrupt thread */ - rc = register_hotcpu_notifier(&fcoe_cpu_notifier); + rc = __register_hotcpu_notifier(&fcoe_cpu_notifier); if (rc) goto out_free; + cpu_notifier_register_done(); + /* Setup link change notification */ fcoe_dev_setup(); @@ -2655,6 +2659,9 @@ out_free: for_each_online_cpu(cpu) { fcoe_percpu_thread_destroy(cpu); } + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); destroy_workqueue(fcoe_wq); return rc; @@ -2687,11 +2694,15 @@ static void __exit fcoe_exit(void) } rtnl_unlock(); - unregister_hotcpu_notifier(&fcoe_cpu_notifier); + cpu_notifier_register_begin(); for_each_online_cpu(cpu) fcoe_percpu_thread_destroy(cpu); + __unregister_hotcpu_notifier(&fcoe_cpu_notifier); + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); /* From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: [PATCH v2 35/52] scsi, fcoe: Fix CPU hotplug callback registration Date: Fri, 14 Feb 2014 13:27:05 +0530 Message-ID: <20140214075704.22701.27489.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, Robert Love , "James E.J. Bottomley" , Ingo Molnar , fcoe-devel@open-fcoe.org, linux-scsi@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 fcoe code in scsi by using this latter form of callback registration. Cc: Robert Love Cc: "James E.J. Bottomley" Cc: Ingo Molnar Cc: fcoe-devel@open-fcoe.org Cc: linux-scsi@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- drivers/scsi/fcoe/fcoe.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index f317000..d5e105b 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -2633,14 +2633,18 @@ static int __init fcoe_init(void) skb_queue_head_init(&p->fcoe_rx_list); } + cpu_notifier_register_begin(); + for_each_online_cpu(cpu) fcoe_percpu_thread_create(cpu); /* Initialize per CPU interrupt thread */ - rc = register_hotcpu_notifier(&fcoe_cpu_notifier); + rc = __register_hotcpu_notifier(&fcoe_cpu_notifier); if (rc) goto out_free; + cpu_notifier_register_done(); + /* Setup link change notification */ fcoe_dev_setup(); @@ -2655,6 +2659,9 @@ out_free: for_each_online_cpu(cpu) { fcoe_percpu_thread_destroy(cpu); } + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); destroy_workqueue(fcoe_wq); return rc; @@ -2687,11 +2694,15 @@ static void __exit fcoe_exit(void) } rtnl_unlock(); - unregister_hotcpu_notifier(&fcoe_cpu_notifier); + cpu_notifier_register_begin(); for_each_online_cpu(cpu) fcoe_percpu_thread_destroy(cpu); + __unregister_hotcpu_notifier(&fcoe_cpu_notifier); + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); /* From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com ([202.81.31.145]:48692 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751829AbaBNICk (ORCPT ); Fri, 14 Feb 2014 03:02:40 -0500 Received: from /spool/local by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 14 Feb 2014 18:02:38 +1000 From: "Srivatsa S. Bhat" Subject: [PATCH v2 35/52] scsi, fcoe: Fix CPU hotplug callback registration Date: Fri, 14 Feb 2014 13:27:05 +0530 Message-ID: <20140214075704.22701.27489.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, Robert Love , "James E.J. Bottomley" , fcoe-devel@open-fcoe.org, linux-scsi@vger.kernel.org"Srivatsa S. Bhat" Message-ID: <20140214075705.TvyGevOEwfMp2eBAH5RQqmijvrf3km1uTuT3SDxKH1w@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 fcoe code in scsi by using this latter form of callback registration. Cc: Robert Love Cc: "James E.J. Bottomley" Cc: Ingo Molnar Cc: fcoe-devel@open-fcoe.org Cc: linux-scsi@vger.kernel.org Signed-off-by: Srivatsa S. Bhat --- drivers/scsi/fcoe/fcoe.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index f317000..d5e105b 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -2633,14 +2633,18 @@ static int __init fcoe_init(void) skb_queue_head_init(&p->fcoe_rx_list); } + cpu_notifier_register_begin(); + for_each_online_cpu(cpu) fcoe_percpu_thread_create(cpu); /* Initialize per CPU interrupt thread */ - rc = register_hotcpu_notifier(&fcoe_cpu_notifier); + rc = __register_hotcpu_notifier(&fcoe_cpu_notifier); if (rc) goto out_free; + cpu_notifier_register_done(); + /* Setup link change notification */ fcoe_dev_setup(); @@ -2655,6 +2659,9 @@ out_free: for_each_online_cpu(cpu) { fcoe_percpu_thread_destroy(cpu); } + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); destroy_workqueue(fcoe_wq); return rc; @@ -2687,11 +2694,15 @@ static void __exit fcoe_exit(void) } rtnl_unlock(); - unregister_hotcpu_notifier(&fcoe_cpu_notifier); + cpu_notifier_register_begin(); for_each_online_cpu(cpu) fcoe_percpu_thread_destroy(cpu); + __unregister_hotcpu_notifier(&fcoe_cpu_notifier); + + cpu_notifier_register_done(); + mutex_unlock(&fcoe_config_mutex); /*