Revision a6a5349d17f2a5c37079826f1a1474c3d08c6b53 authored by Sage Weil on 13 April 2010, 21:07:07 UTC, committed by Sage Weil on 13 April 2010, 21:07:07 UTC
Use a separate class for ceph sockets to prevent lockdep confusion. Because ceph sockets only get passed kernel pointers, there is no dependency from sk_lock -> mmap_sem. If we share the same class as other sockets, lockdep detects a circular dependency from mmap_sem (page fault) -> fs mutex -> sk_lock -> mmap_sem because dependencies are noted from both ceph and user contexts. Using a separate class prevents the sk_lock(ceph) -> mmap_sem dependency and makes lockdep happy. Signed-off-by: Sage Weil <sage@newdream.net>
1 parent e1e4dd0
user-return-notifier.c
#include <linux/user-return-notifier.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/module.h>
static DEFINE_PER_CPU(struct hlist_head, return_notifier_list);
/*
* Request a notification when the current cpu returns to userspace. Must be
* called in atomic context. The notifier will also be called in atomic
* context.
*/
void user_return_notifier_register(struct user_return_notifier *urn)
{
set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
hlist_add_head(&urn->link, &__get_cpu_var(return_notifier_list));
}
EXPORT_SYMBOL_GPL(user_return_notifier_register);
/*
* Removes a registered user return notifier. Must be called from atomic
* context, and from the same cpu registration occured in.
*/
void user_return_notifier_unregister(struct user_return_notifier *urn)
{
hlist_del(&urn->link);
if (hlist_empty(&__get_cpu_var(return_notifier_list)))
clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
}
EXPORT_SYMBOL_GPL(user_return_notifier_unregister);
/* Calls registered user return notifiers */
void fire_user_return_notifiers(void)
{
struct user_return_notifier *urn;
struct hlist_node *tmp1, *tmp2;
struct hlist_head *head;
head = &get_cpu_var(return_notifier_list);
hlist_for_each_entry_safe(urn, tmp1, tmp2, head, link)
urn->on_user_return(urn);
put_cpu_var(return_notifier_list);
}
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