[small patch] ia64 find thread for user rbs address

["bibo,mao" <bibo.mao@intel.com>]

hi,
  I encountered one problem when running ptrace test case, the
situation is this: traced process's syscall parameter needs to
be accessed, but for sys_clone system call with clone_flag
(CLONE_VFORK | CLONE_VM | SIGCHLD) parameter. this syscall's
parameter accessing result is wrong.
  The reason is that with clone_flag(CLONE_VFORK | CLONE_VM | SIGCHLD),
cloned thread's mm point is the same, but tgid is different.
without this patch find_thread_for_addr will return cloned thread,
but not the thread which call sys_clone syscall.

thanks
bibo,mao

--- 2.6.19-rc5.org/arch/ia64/kernel/ptrace.c	2006-11-16 16:23:31.000000000 +0800
+++ 2.6.19-rc5/arch/ia64/kernel/ptrace.c	2006-11-16 16:25:07.000000000 +0800
@@ -607,7 +607,7 @@ find_thread_for_addr (struct task_struct
 	 */
  	list_for_each_safe(this, next, &current->children) {
 		p = list_entry(this, struct task_struct, sibling);
-		if (p->mm != mm)
+		if (p->tgid != child->tgid)
 			continue;
 		if (thread_matches(p, addr)) {
 			child = p;