From: Ingo Molnar <mingo@elte.hu>
Date: Tue, 22 Jan 2008 10:24:58 +0000 (+0100)
Subject: sched: group scheduler, set uid share fix
X-Git-Tag: v2.6.24~20^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c61935fd0e7f087a643827b4bf5ef646963c10fa;p=platform%2Fkernel%2Flinux-3.10.git

sched: group scheduler, set uid share fix

setting cpu share to 1 causes hangs, as reported in:

    http://bugzilla.kernel.org/show_bug.cgi?id=9779

as the default share is 1024, the values of 0 and 1 can indeed
cause problems. Limit it to 2 or higher values.

These values can only be set by the root user - but still it
makes sense to protect against nonsensical values.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index 37cf07a..e76b11c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7153,6 +7153,14 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
 {
 	int i;
 
+	/*
+	 * A weight of 0 or 1 can cause arithmetics problems.
+	 * (The default weight is 1024 - so there's no practical
+	 *  limitation from this.)
+	 */
+	if (shares < 2)
+		shares = 2;
+
 	spin_lock(&tg->lock);
 	if (tg->shares == shares)
 		goto done;