mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-30 08:04:13 +08:00
8e7cac7980
fork() clones all thread_info flags, including TIF_USER_RETURN_NOTIFY; if the new task is first scheduled on a cpu which doesn't have user return notifiers set, this causes user return notifiers to trigger without any way of clearing itself. This is easy to trigger with a forky workload on the host in parallel with kvm, resulting in a cpu in an endless loop on the verge of returning to userspace. Fix by dropping the TIF_USER_RETURN_NOTIFY immediately after fork. Signed-off-by: Avi Kivity <avi@redhat.com> LKML-Reference: <1259505288-16559-1-git-send-email-avi@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
#ifndef _LINUX_USER_RETURN_NOTIFIER_H
|
|
#define _LINUX_USER_RETURN_NOTIFIER_H
|
|
|
|
#ifdef CONFIG_USER_RETURN_NOTIFIER
|
|
|
|
#include <linux/list.h>
|
|
#include <linux/sched.h>
|
|
|
|
struct user_return_notifier {
|
|
void (*on_user_return)(struct user_return_notifier *urn);
|
|
struct hlist_node link;
|
|
};
|
|
|
|
|
|
void user_return_notifier_register(struct user_return_notifier *urn);
|
|
void user_return_notifier_unregister(struct user_return_notifier *urn);
|
|
|
|
static inline void propagate_user_return_notify(struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
if (test_tsk_thread_flag(prev, TIF_USER_RETURN_NOTIFY)) {
|
|
clear_tsk_thread_flag(prev, TIF_USER_RETURN_NOTIFY);
|
|
set_tsk_thread_flag(next, TIF_USER_RETURN_NOTIFY);
|
|
}
|
|
}
|
|
|
|
void fire_user_return_notifiers(void);
|
|
|
|
static inline void clear_user_return_notifier(struct task_struct *p)
|
|
{
|
|
clear_tsk_thread_flag(p, TIF_USER_RETURN_NOTIFY);
|
|
}
|
|
|
|
#else
|
|
|
|
struct user_return_notifier {};
|
|
|
|
static inline void propagate_user_return_notify(struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
}
|
|
|
|
static inline void fire_user_return_notifiers(void) {}
|
|
|
|
static inline void clear_user_return_notifier(struct task_struct *p) {}
|
|
|
|
#endif
|
|
|
|
#endif
|