proc: fix the threaded /proc/self

ebiederm · Linus Torvalds · commit c6caeb7c4544 · 2008-02-08T09:22:24.000-08:00
Long ago when the CLONE_THREAD support first went it someone thought it
would be wise to point /proc/self at /proc/&lt;tgid&gt; instead of /proc/&lt;pid&gt;.

Given that /proc/&lt;tgid&gt; can return information about a very different task
(if enough things have been unshared) then our current process /proc/&lt;tgid&gt;
seems blatantly wrong.  So far I have yet to think up an example where the
current behavior would be advantageous, and I can see several places where
it is seriously non-intuitive.

We may be stuck with the current broken behavior for backwards
compatibility reasons but lets try fixing our ancient bug for the 2.6.25
time frame and see if anyone screams.

Signed-off-by: Eric W. Biederman &lt;ebiederm@xmission.com&gt;
Acked-by: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: "Guillaume Chazarain" &lt;guichaz@yahoo.fr&gt;
Cc: "Pavel Emelyanov" &lt;xemul@openvz.org&gt;
Cc: "Rafael J. Wysocki" &lt;rjw@sisk.pl&gt;
Cc: Oleg Nesterov &lt;oleg@tv-sign.ru&gt;
Cc: Roland McGrath &lt;roland@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/fs/proc/base.c b/fs/proc/base.c
@@ -2102,22 +2102,22 @@ static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
 			      int buflen)
 {
 	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-	pid_t tgid = task_tgid_nr_ns(current, ns);
+	pid_t pid = task_pid_nr_ns(current, ns);
 	char tmp[PROC_NUMBUF];
-	if (!tgid)
+	if (!pid)
 		return -ENOENT;
-	sprintf(tmp, "%d", tgid);
+	sprintf(tmp, "%d", pid);
 	return vfs_readlink(dentry,buffer,buflen,tmp);
 }
 
 static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
 	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-	pid_t tgid = task_tgid_nr_ns(current, ns);
+	pid_t pid = task_pid_nr_ns(current, ns);
 	char tmp[PROC_NUMBUF];
-	if (!tgid)
+	if (!pid)
 		return ERR_PTR(-ENOENT);
-	sprintf(tmp, "%d", task_tgid_nr_ns(current, ns));
+	sprintf(tmp, "%d", pid);
 	return ERR_PTR(vfs_follow_link(nd,tmp));
 }
 
