diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2013-07-09 00:26:32 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@rostedt.homelinux.com> | 2014-03-24 18:27:10 -0400 |
| commit | 36dedc2a1c6d217d6616ae694bb439632e8a70c9 (patch) | |
| tree | b71363ad52ec66f35fe932d248aa94d383ad9fd8 | |
| parent | 4cad52a9ab3ba5e9ec5d4300b126439f8b934787 (diff) | |
list_bl.h: fix it for for !SMP && !DEBUG_SPINLOCK
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>
| -rw-r--r-- | include/linux/list_bl.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/list_bl.h b/include/linux/list_bl.h index ddfd46a88f93..becd7a61263f 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 } |