From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751502AbdCRMl4 (ORCPT ); Sat, 18 Mar 2017 08:41:56 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:60851 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751134AbdCRMlz (ORCPT ); Sat, 18 Mar 2017 08:41:55 -0400 Date: Sat, 18 Mar 2017 12:26:42 +0100 (CET) From: Thomas Gleixner To: Linus Torvalds cc: LKML , Andrew Morton , Ingo Molnar , "H. Peter Anvin" Subject: [GIT pull] smp/hotplug fix for 4.11 Message-ID: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, please pull the latest smp-urgent-for-linus git tree from: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git smp-urgent-for-linus A single fix preventing the concurrent execution of the CPU hotplug callback install/invocation machinery. Long standing bug caused by a massive brain slip of that Gleixner dude, which went unnoticed for almost a year. Thanks, tglx ------------------> Sebastian Andrzej Siewior (1): cpu/hotplug: Serialize callback invocations proper kernel/cpu.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index f7c063239fa5..37b223e4fc05 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1335,26 +1335,21 @@ static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name, struct cpuhp_step *sp; int ret = 0; - mutex_lock(&cpuhp_state_mutex); - if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) { ret = cpuhp_reserve_state(state); if (ret < 0) - goto out; + return ret; state = ret; } sp = cpuhp_get_step(state); - if (name && sp->name) { - ret = -EBUSY; - goto out; - } + if (name && sp->name) + return -EBUSY; + sp->startup.single = startup; sp->teardown.single = teardown; sp->name = name; sp->multi_instance = multi_instance; INIT_HLIST_HEAD(&sp->list); -out: - mutex_unlock(&cpuhp_state_mutex); return ret; } @@ -1428,6 +1423,7 @@ int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, return -EINVAL; get_online_cpus(); + mutex_lock(&cpuhp_state_mutex); if (!invoke || !sp->startup.multi) goto add_node; @@ -1447,16 +1443,14 @@ int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node, if (ret) { if (sp->teardown.multi) cpuhp_rollback_install(cpu, state, node); - goto err; + goto unlock; } } add_node: ret = 0; - mutex_lock(&cpuhp_state_mutex); hlist_add_head(node, &sp->list); +unlock: mutex_unlock(&cpuhp_state_mutex); - -err: put_online_cpus(); return ret; } @@ -1491,6 +1485,7 @@ int __cpuhp_setup_state(enum cpuhp_state state, return -EINVAL; get_online_cpus(); + mutex_lock(&cpuhp_state_mutex); ret = cpuhp_store_callbacks(state, name, startup, teardown, multi_instance); @@ -1524,6 +1519,7 @@ int __cpuhp_setup_state(enum cpuhp_state state, } } out: + mutex_unlock(&cpuhp_state_mutex); put_online_cpus(); /* * If the requested state is CPUHP_AP_ONLINE_DYN, return the @@ -1547,6 +1543,8 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, return -EINVAL; get_online_cpus(); + mutex_lock(&cpuhp_state_mutex); + if (!invoke || !cpuhp_get_teardown_cb(state)) goto remove; /* @@ -1563,7 +1561,6 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, } remove: - mutex_lock(&cpuhp_state_mutex); hlist_del(node); mutex_unlock(&cpuhp_state_mutex); put_online_cpus(); @@ -1571,6 +1568,7 @@ int __cpuhp_state_remove_instance(enum cpuhp_state state, return 0; } EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance); + /** * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state * @state: The state to remove @@ -1589,6 +1587,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) get_online_cpus(); + mutex_lock(&cpuhp_state_mutex); if (sp->multi_instance) { WARN(!hlist_empty(&sp->list), "Error: Removing state %d which has instances left.\n", @@ -1613,6 +1612,7 @@ void __cpuhp_remove_state(enum cpuhp_state state, bool invoke) } remove: cpuhp_store_callbacks(state, NULL, NULL, NULL, false); + mutex_unlock(&cpuhp_state_mutex); put_online_cpus(); } EXPORT_SYMBOL(__cpuhp_remove_state);