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tag: v2.6.18-rc1
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/*
* linux/kernel/futex_compat.c
*
* Futex compatibililty routines.
*
* Copyright 2006, Red Hat, Inc., Ingo Molnar
*/

#include <linux/linkage.h>
#include <linux/compat.h>
#include <linux/futex.h>

#include <asm/uaccess.h>

/*
* Walk curr->robust_list (very carefully, it's a userspace list!)
* and mark any locks found there dead, and notify any waiters.
*
* We silently return on any sign of list-walking problem.
*/
void compat_exit_robust_list(struct task_struct *curr)
{
struct compat_robust_list_head __user *head = curr->compat_robust_list;
struct robust_list __user *entry, *pending;
compat_uptr_t uentry, upending;
unsigned int limit = ROBUST_LIST_LIMIT;
compat_long_t futex_offset;

/*
* Fetch the list head (which was registered earlier, via
* sys_set_robust_list()):
*/
if (get_user(uentry, &head->list.next))
return;
entry = compat_ptr(uentry);
/*
* Fetch the relative futex offset:
*/
if (get_user(futex_offset, &head->futex_offset))
return;
/*
* Fetch any possibly pending lock-add first, and handle it
* if it exists:
*/
if (get_user(upending, &head->list_op_pending))
return;
pending = compat_ptr(upending);
if (upending)
handle_futex_death((void *)pending + futex_offset, curr);

while (compat_ptr(uentry) != &head->list) {
/*
* A pending lock might already be on the list, so
* dont process it twice:
*/
if (entry != pending)
if (handle_futex_death((void *)entry + futex_offset,
curr))
return;

/*
* Fetch the next entry in the list:
*/
if (get_user(uentry, (compat_uptr_t *)&entry->next))
return;
entry = compat_ptr(uentry);
/*
* Avoid excessively long or circular lists:
*/
if (!--limit)
break;

cond_resched();
}
}

asmlinkage long
compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
compat_size_t len)
{
if (unlikely(len != sizeof(*head)))
return -EINVAL;

current->compat_robust_list = head;

return 0;
}

asmlinkage long
compat_sys_get_robust_list(int pid, compat_uptr_t *head_ptr,
compat_size_t __user *len_ptr)
{
struct compat_robust_list_head *head;
unsigned long ret;

if (!pid)
head = current->compat_robust_list;
else {
struct task_struct *p;

ret = -ESRCH;
read_lock(&tasklist_lock);
p = find_task_by_pid(pid);
if (!p)
goto err_unlock;
ret = -EPERM;
if ((current->euid != p->euid) && (current->euid != p->uid) &&
!capable(CAP_SYS_PTRACE))
goto err_unlock;
head = p->compat_robust_list;
read_unlock(&tasklist_lock);
}

if (put_user(sizeof(*head), len_ptr))
return -EFAULT;
return put_user(ptr_to_compat(head), head_ptr);

err_unlock:
read_unlock(&tasklist_lock);

return ret;
}

asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
struct compat_timespec __user *utime, u32 __user *uaddr2,
u32 val3)
{
struct timespec t;
unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
int val2 = 0;

if (utime && (op == FUTEX_WAIT || op == FUTEX_LOCK_PI)) {
if (get_compat_timespec(&t, utime))
return -EFAULT;
if (!timespec_valid(&t))
return -EINVAL;
if (op == FUTEX_WAIT)
timeout = timespec_to_jiffies(&t) + 1;
else {
timeout = t.tv_sec;
val2 = t.tv_nsec;
}
}
if (op == FUTEX_REQUEUE || op == FUTEX_CMP_REQUEUE)
val2 = (int) (unsigned long) utime;

return do_futex(uaddr, op, val, timeout, uaddr2, val2, val3);
}
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