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futex: Protect pid lookup in compat code with RCU 

find_task_by_vpid() in compat_sys_get_robust_list() does not require
tasklist_lock. It can be protected with rcu_read_lock as done in
sys_get_robust_list() already.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
This commit is contained in:
Thomas Gleixner 2009-12-01 14:02:00 +01:00
parent 2b876f95d0
commit f409adf5b1
1 changed files with 3 additions and 3 deletions
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6
kernel/futex_compat.c
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@ -146,7 +146,7 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
struct task_struct *p;
ret = -ESRCH;
read_lock(&tasklist_lock);
rcu_read_lock();
p = find_task_by_vpid(pid);
if (!p)
goto err_unlock;
@ -157,7 +157,7 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
!capable(CAP_SYS_PTRACE))
goto err_unlock;
head = p->compat_robust_list;
read_unlock(&tasklist_lock);
rcu_read_unlock();
}
if (put_user(sizeof(*head), len_ptr))
@ -165,7 +165,7 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
return put_user(ptr_to_compat(head), head_ptr);
err_unlock:
read_unlock(&tasklist_lock);
rcu_read_unlock();
return ret;
}