netdev - Re: 2.6.24 BUG: soft lockup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 28 Mar 2008 09:22:34 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	David Miller <davem@...emloft.net>
Cc:	Matheos.Worku@....COM, jesse.brandeburg@...el.com,
	jarkao2@...il.com, netdev@...r.kernel.org, hadi@...erus.ca
Subject: Re: 2.6.24 BUG: soft lockup - CPU#X

On Thu, Mar 27, 2008 at 05:34:18PM -0700, David Miller wrote:
>
> The first cpu will get into __qdisc_run(), but the other
> ones will just q->enqueue() and exit since the first cpu
> has indicated it is processing the qdisc.

Indeed.  Since I created the problem it's only fair that I get
to fix it too :)

[NET]: Add preemption point in qdisc_run

The qdisc_run loop is currently unbounded and runs entirely
in a softirq.  This is bad as it may create an unbounded softirq
run.

This patch fixes this by calling need_resched and breaking out
if necessary.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

Thanks,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 10b5c08..80d53dd 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -187,6 +187,10 @@ void __qdisc_run(struct net_device *dev)
 	do {
 		if (!qdisc_restart(dev))
 			break;
+		if (need_resched()) {
+			netif_schedule(dev);
+			break;
+		}
 	} while (!netif_queue_stopped(dev));
 
 	clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html