From 8c60ea146499b9d2a81ceb5e3e0bd215ef0b6287 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat" Date: Tue, 11 Mar 2014 02:07:57 +0530 Subject: [PATCH] x86, intel, cacheinfo: 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 intel cacheinfo code in x86 by using this latter form of callback registration. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki --- arch/x86/kernel/cpu/intel_cacheinfo.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index 0641113e2965..a952e9c85b6f 100644 --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -1225,21 +1225,24 @@ static struct notifier_block cacheinfo_cpu_notifier = { static int __init cache_sysfs_init(void) { - int i; + int i, err = 0; if (num_cache_leaves == 0) return 0; + cpu_notifier_register_begin(); for_each_online_cpu(i) { - int err; struct device *dev = get_cpu_device(i); err = cache_add_dev(dev); if (err) - return err; + goto out; } - register_hotcpu_notifier(&cacheinfo_cpu_notifier); - return 0; + __register_hotcpu_notifier(&cacheinfo_cpu_notifier); + +out: + cpu_notifier_register_done(); + return err; } device_initcall(cache_sysfs_init); -- 2.34.1