From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
"Carsten Emde" <C.Emde@osadl.org>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
"John Kacur" <jkacur@redhat.com>,
stable-rt@vger.kernel.org,
"Paul Gortmaker" <paul.gortmaker@windriver.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Subject: [PATCH RT 05/19] list_bl.h: fix it for for !SMP && !DEBUG_SPINLOCK
Date: Sun, 08 Sep 2013 11:14:00 -0400 [thread overview]
Message-ID: <20130908151446.449394004@goodmis.org> (raw)
In-Reply-To: 20130908151355.362583092@goodmis.org
[-- Attachment #1: 0005-list_bl.h-fix-it-for-for-SMP-DEBUG_SPINLOCK.patch --]
[-- Type: TEXT/PLAIN, Size: 2052 bytes --]
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
The patch "list_bl.h: make list head locking RT safe" introduced
an unconditional
__set_bit(0, (unsigned long *)b);
in void hlist_bl_lock(struct hlist_bl_head *b). This clobbers the value
of b->first. When the value of b->first is retrieved using
hlist_bl_first the clobbering is undone using
(unsigned long)h->first & ~LIST_BL_LOCKMASK
and so depending on LIST_BL_LOCKMASK being one. But LIST_BL_LOCKMASK is
only one if at least on of CONFIG_SMP and CONFIG_DEBUG_SPINLOCK are
defined. Without these the value returned by hlist_bl_first has the
zeroth bit set which likely results in a crash.
So only do the clobbering in the cases where LIST_BL_LOCKMASK is one.
An alternative would be to always define LIST_BL_LOCKMASK to one with
CONFIG_PREEMPT_RT_BASE.
Cc: stable-rt@vger.kernel.org
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/list_bl.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h
index ddfd46a..becd7a6 100644
--- a/include/linux/list_bl.h
+++ b/include/linux/list_bl.h
@@ -131,8 +131,10 @@ static inline void hlist_bl_lock(struct hlist_bl_head *b)
bit_spin_lock(0, (unsigned long *)b);
#else
raw_spin_lock(&b->lock);
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
__set_bit(0, (unsigned long *)b);
#endif
+#endif
}
static inline void hlist_bl_unlock(struct hlist_bl_head *b)
@@ -140,7 +142,9 @@ static inline void hlist_bl_unlock(struct hlist_bl_head *b)
#ifndef CONFIG_PREEMPT_RT_BASE
__bit_spin_unlock(0, (unsigned long *)b);
#else
+#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
__clear_bit(0, (unsigned long *)b);
+#endif
raw_spin_unlock(&b->lock);
#endif
}
--
1.7.10.4
next prev parent reply other threads:[~2013-09-08 15:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-08 15:13 [PATCH RT 00/19] 3.6.11.8-rt41-rc1 stable review Steven Rostedt
2013-09-08 15:13 ` [PATCH RT 01/19] sched/workqueue: Only wake up idle workers if not blocked on sleeping spin lock Steven Rostedt
2013-09-08 15:13 ` [PATCH RT 02/19] x86/mce: fix mce timer interval Steven Rostedt
2013-09-08 15:13 ` [PATCH RT 03/19] genirq: Set irq thread to RT priority on creation Steven Rostedt
2013-09-08 15:13 ` [PATCH RT 04/19] list_bl.h: make list head locking RT safe Steven Rostedt
2013-09-08 15:14 ` Steven Rostedt [this message]
2013-09-08 15:14 ` [PATCH RT 06/19] timers: prepare for full preemption improve Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 07/19] kernel/cpu: fix cpu down problem if kthreads cpu is going down Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 08/19] kernel/hotplug: restore original cpu mask oncpu/down Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 09/19] gpu: i915: allow the user not to do the wbinvd Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 10/19] drm/i915: drop trace_i915_gem_ring_dispatch on rt Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 11/19] sched: Distangle worker accounting from rqlock Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 12/19] rt,ntp: Move call to schedule_delayed_work() to helper thread Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 13/19] hpsa: fix warning with smp_processor_id() in preemptible section Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 14/19] hwlat-detector: Update hwlat_detector to add outer loop detection Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 15/19] hwlat-detect/trace: Export trace_clock_local for hwlat-detector Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 16/19] hwlat-detector: Use trace_clock_local if available Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 17/19] hwlat-detector: Use thread instead of stop machine Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 18/19] genirq: do not invoke the affinity callback via a workqueue Steven Rostedt
2013-09-08 15:14 ` [PATCH RT 19/19] Linux 3.6.11.8-rt41-rc1 Steven Rostedt
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