From 7229b6d0b2a9e62d5eb4886dcd0137664c735718 Mon Sep 17 00:00:00 2001 From: Srivatsa S. Bhat Date: Tue, 11 Mar 2014 02:09:45 +0530 Subject: scsi, bnx2fc: 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 bnx2fc code in scsi by using this latter form of callback registration. Cc: Eddie Wai Cc: "James E.J. Bottomley" Cc: Ingo Molnar Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'drivers/scsi/bnx2fc') diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c index 9b948505d118..c4ec235baead 100644 --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c @@ -2586,12 +2586,16 @@ static int __init bnx2fc_mod_init(void) spin_lock_init(&p->fp_work_lock); } + cpu_notifier_register_begin(); + for_each_online_cpu(cpu) { bnx2fc_percpu_thread_create(cpu); } /* Initialize per CPU interrupt thread */ - register_hotcpu_notifier(&bnx2fc_cpu_notifier); + __register_hotcpu_notifier(&bnx2fc_cpu_notifier); + + cpu_notifier_register_done(); cnic_register_driver(CNIC_ULP_FCOE, &bnx2fc_cnic_cb); @@ -2656,13 +2660,17 @@ static void __exit bnx2fc_mod_exit(void) if (l2_thread) kthread_stop(l2_thread); - unregister_hotcpu_notifier(&bnx2fc_cpu_notifier); + cpu_notifier_register_begin(); /* Destroy per cpu threads */ for_each_online_cpu(cpu) { bnx2fc_percpu_thread_destroy(cpu); } + __unregister_hotcpu_notifier(&bnx2fc_cpu_notifier); + + cpu_notifier_register_done(); + destroy_workqueue(bnx2fc_wq); /* * detach from scsi transport -- cgit v1.2.3