[PATCH 41/51] thermal, x86-pkg-temp: Fix CPU hotplug callback registration
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SUPERSEDED
From: Srivatsa S. Bhat <hidden>
Date: 2014-02-05 22:17:24
Also in:
lkml
Subsystem:
the rest, thermal · Maintainers:
Linus Torvalds, Rafael J. Wysocki, Daniel Lezcano
Revision v1 of 3 in this series.
Revisions (3)
- v1 current
- v2 [diff vs current]
- v3 [diff vs current]
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_maps_update_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_maps_update_done(); Fix the thermal x86-pkg-temp code by using this latter form of callback registration. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <redacted> Cc: linux-pm@vger.kernel.org Signed-off-by: Srivatsa S. Bhat <redacted> --- drivers/thermal/x86_pkg_temp_thermal.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/thermal/x86_pkg_temp_thermal.c b/drivers/thermal/x86_pkg_temp_thermal.c
index 972e1c7..55f9eac 100644
--- a/drivers/thermal/x86_pkg_temp_thermal.c
+++ b/drivers/thermal/x86_pkg_temp_thermal.c@@ -589,12 +589,12 @@ static int __init pkg_temp_thermal_init(void) platform_thermal_package_rate_control = pkg_temp_thermal_platform_thermal_rate_control; - get_online_cpus(); + cpu_maps_update_begin(); for_each_online_cpu(i) if (get_core_online(i)) goto err_ret; - register_hotcpu_notifier(&pkg_temp_thermal_notifier); - put_online_cpus(); + __register_hotcpu_notifier(&pkg_temp_thermal_notifier); + cpu_maps_update_done(); pkg_temp_debugfs_init(); /* Don't care if fails */
@@ -603,7 +603,7 @@ static int __init pkg_temp_thermal_init(void) err_ret: for_each_online_cpu(i) put_core_offline(i); - put_online_cpus(); + cpu_maps_update_done(); kfree(pkg_work_scheduled); platform_thermal_package_notify = NULL; platform_thermal_package_rate_control = NULL;
@@ -616,8 +616,8 @@ static void __exit pkg_temp_thermal_exit(void) struct phy_dev_entry *phdev, *n; int i; - get_online_cpus(); - unregister_hotcpu_notifier(&pkg_temp_thermal_notifier); + cpu_maps_update_begin(); + __unregister_hotcpu_notifier(&pkg_temp_thermal_notifier); mutex_lock(&phy_dev_list_mutex); list_for_each_entry_safe(phdev, n, &phy_dev_list, list) { /* Retore old MSR value for package thermal interrupt */
@@ -635,7 +635,7 @@ static void __exit pkg_temp_thermal_exit(void) for_each_online_cpu(i) cancel_delayed_work_sync( &per_cpu(pkg_temp_thermal_threshold_work, i)); - put_online_cpus(); + cpu_maps_update_done(); kfree(pkg_work_scheduled);