linux-kernel - [PATCH] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels

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]

Message-ID: <4F26A05E.2000300@LiPPERTEmbedded.de>
Date:	Mon, 30 Jan 2012 14:51:26 +0100
From:	Jens Rottmann <JRottmann@...PERTEmbedded.de>
To:	Thomas Gleixner <tglx@...utronix.de>,
	John Stultz <johnstul@...ibm.com>
CC:	Andres Salomon <dilinger@...ued.net>, linux-kernel@...r.kernel.org,
	linux-geode@...ts.infradead.org
Subject: [PATCH] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels

cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels

On SMP-capable kernels (e.g. generic distro kernel) the cs5535-clockevt driver
loads but is not actually used.

Setting cpumask to cpu_all_mask works for UP-only kernels, but if compiled for
SMP - though still running on the same UP hardware -
kernel/time/tick-common.c:tick_check_new_device() reads this as "non-cpu-local"
and silently ignores the device.

If we leave cpumask unset clockevents_register_device() will initialize it and
the cs5535-clockevt driver will be used no matter how the kernel was compiled.
Should anyone ever manage to stick a CS553x in an SMP system (is this even
possible?) then a warning will be printed.  This is fine as the cs5535-clockevt
driver was never written/tested for SMP.

If bisecting led you here this patch may have exposed a pre-existing MFGPT
problem.  Configure for UP-only and re-check.

Signed-off-by: Jens Rottmann <JRottmann@...PERTEmbedded.de>
Acked-by: Andres Salomon <dilinger@...ued.net>
---

Hi,

could you please take this, for linux-next?

Thanks,
Jens

--- linux-3.2-rc6/drivers/clocksource/cs5535-clockevt.c
+++ use_mfgpt_on_smp_kernels/drivers/clocksource/cs5535-clockevt.c
@@ -100,7 +100,6 @@ static struct clock_event_device cs5535_
 	.set_mode = mfgpt_set_mode,
 	.set_next_event = mfgpt_next_event,
 	.rating = 250,
-	.cpumask = cpu_all_mask,
 	.shift = 32
 };

_

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/