From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938835AbdEXI3v (ORCPT ); Wed, 24 May 2017 04:29:51 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:58003 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765211AbdEXI0Y (ORCPT ); Wed, 24 May 2017 04:26:24 -0400 Message-Id: <20170524081547.571278910@linutronix.de> User-Agent: quilt/0.63-1 Date: Wed, 24 May 2017 10:15:18 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Steven Rostedt , Sebastian Siewior , Paul McKenney , Steffen Klassert , linux-crypto@vger.kernel.org Subject: [patch V3 07/32] padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() References: <20170524081511.203800767@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=padata_Avoid_nested_calls_to_get_online_cpus()_in_pcrypt_init_padata().patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior pcrypt_init_padata() cpus_read_lock() padata_alloc_possible() padata_alloc() cpus_read_lock() The nested call to cpus_read_lock() works with the current implementation, but prevents the conversion to a percpu rwsem. The other caller of padata_alloc_possible() is pcrypt_init_padata() which calls from a cpus_read_lock() protected region as well. Remove the cpus_read_lock() call in padata_alloc() and document the calling convention. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: Steffen Klassert Cc: Peter Zijlstra Cc: Steven Rostedt Cc: linux-crypto@vger.kernel.org --- kernel/padata.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/kernel/padata.c +++ b/kernel/padata.c @@ -940,6 +940,8 @@ static struct kobj_type padata_attr_type * @wq: workqueue to use for the allocated padata instance * @pcpumask: cpumask that will be used for padata parallelization * @cbcpumask: cpumask that will be used for padata serialization + * + * Must be called from a cpus_read_lock() protected region */ static struct padata_instance *padata_alloc(struct workqueue_struct *wq, const struct cpumask *pcpumask, @@ -952,7 +954,6 @@ static struct padata_instance *padata_al if (!pinst) goto err; - get_online_cpus(); if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL)) goto err_free_inst; if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) { @@ -976,14 +977,12 @@ static struct padata_instance *padata_al pinst->flags = 0; - put_online_cpus(); - BLOCKING_INIT_NOTIFIER_HEAD(&pinst->cpumask_change_notifier); kobject_init(&pinst->kobj, &padata_attr_type); mutex_init(&pinst->lock); #ifdef CONFIG_HOTPLUG_CPU - cpuhp_state_add_instance_nocalls(hp_online, &pinst->node); + cpuhp_state_add_instance_nocalls_cpuslocked(hp_online, &pinst->node); #endif return pinst; @@ -992,7 +991,6 @@ static struct padata_instance *padata_al free_cpumask_var(pinst->cpumask.cbcpu); err_free_inst: kfree(pinst); - put_online_cpus(); err: return NULL; } @@ -1003,9 +1001,12 @@ static struct padata_instance *padata_al * parallel workers. * * @wq: workqueue to use for the allocated padata instance + * + * Must be called from a cpus_read_lock() protected region */ struct padata_instance *padata_alloc_possible(struct workqueue_struct *wq) { + lockdep_assert_cpus_held(); return padata_alloc(wq, cpu_possible_mask, cpu_possible_mask); } EXPORT_SYMBOL(padata_alloc_possible);