Messages in this thread Patch in this message | | | Date | Wed, 24 May 2017 10:15:18 +0200 | From | Thomas Gleixner <> | Subject | [patch V3 07/32] padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() |
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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 <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steffen Klassert <steffen.klassert@secunet.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> 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);
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