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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-11 00:39:52 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 16:43:45 +0400
commitcd45ae38035d1b7f98dd92429b59bbc8ba9443e9 (patch)
tree5f8eb5706b2f4814882116ead755f0842b1fa38f /drivers/scsi/fcoe/fcoe.c
parent7229b6d0b2a9e62d5eb4886dcd0137664c735718 (diff)
downloadlinux-cd45ae38035d1b7f98dd92429b59bbc8ba9443e9.tar.xz
scsi, fcoe: Fix CPU hotplug callback registration
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 <robert.w.love@intel.com> Cc: "James E.J. Bottomley" <JBottomley@parallels.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/scsi/fcoe/fcoe.c')
-rw-r--r--drivers/scsi/fcoe/fcoe.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index f3170008ae71..d5e105b173f0 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);
/*