Re: [1/2][PATCH] nproc: netlink access to /proc information

[Roger Luethi <rl@hellgate.ch>]

I failed to mention that the patch is missing some rather basic locking
(say, in nproc_select_pid). Yeah, it is _that_ experimental :-/. I ignored
the locking issue when mulling over the semantics of the new interface and
forgot it later.

The patch below should be an improvement.

Roger

--- kernel/nproc.c.01	2004-08-27 15:38:36.686602557 +0200
+++ kernel/nproc.c	2004-08-27 15:38:36.686602557 +0200
@@ -278,18 +278,23 @@ int nproc_select_pid(struct nlmsghdr *nl
 
 	for (i = 0; i < tcnt; i++) {
 		task_t *tsk;
+		read_lock(&tasklist_lock);
 		tsk = find_task_by_pid(pids[i]);
+		if (tsk)
+			get_task_struct(tsk);
+		read_unlock(&tasklist_lock);
+		if (!tsk)
+			goto err_srch;
 		pdebug("task found for pid %d: %s.\n", pids[i], tsk->comm);
-		if (!tsk) {
-			err = -ESRCH;
-			goto out;
-		}
 		err = nproc_pid_fields(nlh, fdata, len, tsk);
+		put_task_struct(tsk);
 	}
 
-out:
 	return err;
 
+err_srch:
+	return -ESRCH;
+
 err_inval:
 	return -EINVAL;
 }