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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-03-10 16:39:45 -0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-20 08:43:44 -0400
commit7229b6d0b2a9e62d5eb4886dcd0137664c735718 (patch)
tree9c20d95dd9b4ab0171b83baa6e564d77d4a6f1e1 /drivers/scsi
parentbc0003c93f0e68b5383fb36579f7efa267b7dc16 (diff)
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 <eddie.wai@broadcom.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')
-rw-r--r--drivers/scsi/bnx2fc/bnx2fc_fcoe.c12
1 files changed, 10 insertions, 2 deletions
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)
2586 spin_lock_init(&p->fp_work_lock); 2586 spin_lock_init(&p->fp_work_lock);
2587 } 2587 }
2588 2588
2589 cpu_notifier_register_begin();
2590
2589 for_each_online_cpu(cpu) { 2591 for_each_online_cpu(cpu) {
2590 bnx2fc_percpu_thread_create(cpu); 2592 bnx2fc_percpu_thread_create(cpu);
2591 } 2593 }
2592 2594
2593 /* Initialize per CPU interrupt thread */ 2595 /* Initialize per CPU interrupt thread */
2594 register_hotcpu_notifier(&bnx2fc_cpu_notifier); 2596 __register_hotcpu_notifier(&bnx2fc_cpu_notifier);
2597
2598 cpu_notifier_register_done();
2595 2599
2596 cnic_register_driver(CNIC_ULP_FCOE, &bnx2fc_cnic_cb); 2600 cnic_register_driver(CNIC_ULP_FCOE, &bnx2fc_cnic_cb);
2597 2601
@@ -2656,13 +2660,17 @@ static void __exit bnx2fc_mod_exit(void)
2656 if (l2_thread) 2660 if (l2_thread)
2657 kthread_stop(l2_thread); 2661 kthread_stop(l2_thread);
2658 2662
2659 unregister_hotcpu_notifier(&bnx2fc_cpu_notifier); 2663 cpu_notifier_register_begin();
2660 2664
2661 /* Destroy per cpu threads */ 2665 /* Destroy per cpu threads */
2662 for_each_online_cpu(cpu) { 2666 for_each_online_cpu(cpu) {
2663 bnx2fc_percpu_thread_destroy(cpu); 2667 bnx2fc_percpu_thread_destroy(cpu);
2664 } 2668 }
2665 2669
2670 __unregister_hotcpu_notifier(&bnx2fc_cpu_notifier);
2671
2672 cpu_notifier_register_done();
2673
2666 destroy_workqueue(bnx2fc_wq); 2674 destroy_workqueue(bnx2fc_wq);
2667 /* 2675 /*
2668 * detach from scsi transport 2676 * detach from scsi transport