From c5a81c8ff816d89941fe86961b286765d6ca2f5f Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 24 May 2017 10:15:18 +0200 Subject: padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() 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 Tested-by: Paul E. McKenney Acked-by: Ingo Molnar Cc: Steffen Klassert Cc: Peter Zijlstra Cc: Steven Rostedt Cc: linux-crypto@vger.kernel.org Link: http://lkml.kernel.org/r/20170524081547.571278910@linutronix.de --- kernel/padata.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel/padata.c') diff --git a/kernel/padata.c b/kernel/padata.c index 0c708f648853..868f947166d7 100644 --- 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_alloc(struct workqueue_struct *wq, 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_alloc(struct workqueue_struct *wq, 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 @@ err_free_masks: free_cpumask_var(pinst->cpumask.cbcpu); err_free_inst: kfree(pinst); - put_online_cpus(); err: return NULL; } @@ -1003,9 +1001,12 @@ err: * 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); -- cgit