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Date: Thu, 26 Feb 2004 15:19:17 -0800
From: Andrew Morton <akpm@osdl.org>
To: Kingsley Cheung <kingsley@aurema.com>
Cc: davidm@hpl.hp.com, peter@chubb.wattle.id.au, linux-kernel@vger.kernel.org,
       dan@debian.org
Subject: Re: /proc visibility patch breaks GDB, etc.
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Kingsley Cheung <kingsley@aurema.com> wrote:
>
> Am I correct to assume though that the corresponding change in
> proc_task_lookup() should stay?  The existing behaviour there was that
> one could do say,
> 
> cat /proc/<pid>/task/<tid>/stat, where tid could be any thread and not
> a part of the thread group pid.  

That sounds especially broken - let's hope that nobody has started using it
(but how did you even discover this?  Code audit?)

How's this?

diff -puN fs/proc/base.c~proc-thread-visibility-revert fs/proc/base.c
--- 25/fs/proc/base.c~proc-thread-visibility-revert	Thu Feb 26 15:17:48 2004
+++ 25-akpm/fs/proc/base.c	Thu Feb 26 15:17:48 2004
@@ -1582,13 +1582,14 @@ struct dentry *proc_pid_lookup(struct in
 	read_unlock(&tasklist_lock);
 	if (!task)
 		goto out;
-	if (!thread_group_leader(task))
-		goto out_drop_task;
 
 	inode = proc_pid_make_inode(dir->i_sb, task, PROC_TGID_INO);
 
-	if (!inode)
-		goto out_drop_task;
+
+	if (!inode) {
+		put_task_struct(task);
+		goto out;
+	}
 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
 	inode->i_op = &proc_tgid_base_inode_operations;
 	inode->i_fop = &proc_tgid_base_operations;
@@ -1613,8 +1614,6 @@ struct dentry *proc_pid_lookup(struct in
 		goto out;
 	}
 	return NULL;
-out_drop_task:
-	put_task_struct(task);
 out:
 	return ERR_PTR(-ENOENT);
 }

_