[PATCH RT 4/8] mm: page_alloc: Use local_lock_on() instead of plain spinlock

Steven Rostedt
2012-10-12T01:22:48Z

[-- Attachment #1: 0004-mm-page_alloc-Use-local_lock_on-instead-of-plain-spi.patch --]
[-- Type: text/plain, Size: 2090 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

The plain spinlock while sufficient does not update the local_lock
internals. Use a proper local_lock function instead to ease debugging.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/locallock.h | 11 +++++++++++
mm/page_alloc.c | 4 ++--
2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/linux/locallock.h b/include/linux/locallock.h
index 0161fbb..f1804a3 100644
--- a/include/linux/locallock.h
+++ b/include/linux/locallock.h
@@ -137,6 +137,12 @@ static inline int __local_lock_irqsave(struct local_irq_lock *lv)
_flags = __get_cpu_var(lvar).flags; \
} while (0)

+#define local_lock_irqsave_on(lvar, _flags, cpu) \
+ do { \
+ __local_lock_irqsave(&per_cpu(lvar, cpu)); \
+ _flags = per_cpu(lvar, cpu).flags; \
+ } while (0)
+
static inline int __local_unlock_irqrestore(struct local_irq_lock *lv,
unsigned long flags)
{
@@ -156,6 +162,11 @@ static inline int __local_unlock_irqrestore(struct local_irq_lock *lv,
put_local_var(lvar); \
} while (0)

+#define local_unlock_irqrestore_on(lvar, flags, cpu) \
+ do { \
+ __local_unlock_irqrestore(&per_cpu(lvar, cpu), flags); \
+ } while (0)
+
#define local_spin_trylock_irq(lvar, lock) \
({ \
int __locked; \
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 67202bc..8678a7f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -227,9 +227,9 @@ static DEFINE_LOCAL_IRQ_LOCK(pa_lock);

#ifdef CONFIG_PREEMPT_RT_BASE
# define cpu_lock_irqsave(cpu, flags) \
- spin_lock_irqsave(&per_cpu(pa_lock, cpu).lock, flags)
+ local_lock_irqsave_on(pa_lock, flags, cpu)
# define cpu_unlock_irqrestore(cpu, flags) \
- spin_unlock_irqrestore(&per_cpu(pa_lock, cpu).lock, flags)
+ local_unlock_irqrestore_on(pa_lock, flags, cpu)
#else
# define cpu_lock_irqsave(cpu, flags) local_irq_save(flags)
# define cpu_unlock_irqrestore(cpu, flags) local_irq_restore(flags)
--
1.7.10.4