From: Anton Blanchard <anton@samba.org>
Minimal infrastructure to permit sleep-in-spinlock debug checking on
architectures which do not support preemption.
---
arch/ppc64/Kconfig | 7 +++++++
include/asm-ppc64/hardirq.h | 2 +-
include/linux/preempt.h | 17 +++++++++++------
kernel/sched.c | 4 ++--
4 files changed, 21 insertions(+), 9 deletions(-)
diff -puN arch/ppc64/Kconfig~ppc64-spinlock-sleep-debugging arch/ppc64/Kconfig
--- 25/arch/ppc64/Kconfig~ppc64-spinlock-sleep-debugging 2004-02-11 21:15:05.000000000 -0800
+++ 25-akpm/arch/ppc64/Kconfig 2004-02-11 21:15:05.000000000 -0800
@@ -357,6 +357,13 @@ config DEBUG_INFO
debugging info resulting in a larger kernel image.
Say Y here only if you plan to use gdb to debug the kernel.
If you don't debug the kernel, you can say N.
+
+config DEBUG_SPINLOCK_SLEEP
+ bool "Sleep-inside-spinlock checking"
+ depends on DEBUG_KERNEL
+ help
+ If you say Y here, various routines which may sleep will become very
+ noisy if they are called with a spinlock held.
endmenu
diff -puN include/asm-ppc64/hardirq.h~ppc64-spinlock-sleep-debugging include/asm-ppc64/hardirq.h
--- 25/include/asm-ppc64/hardirq.h~ppc64-spinlock-sleep-debugging 2004-02-11 21:15:05.000000000 -0800
+++ 25-akpm/include/asm-ppc64/hardirq.h 2004-02-11 21:15:05.000000000 -0800
@@ -80,7 +80,7 @@ typedef struct {
#define irq_enter() (preempt_count() += HARDIRQ_OFFSET)
-#ifdef CONFIG_PREEMPT
+#if defined(CONFIG_PREEMPT) || defined(CONFIG_DEBUG_SPINLOCK_SLEEP)
# define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) != kernel_locked())
# define IRQ_EXIT_OFFSET (HARDIRQ_OFFSET-1)
#else
diff -puN include/linux/preempt.h~ppc64-spinlock-sleep-debugging include/linux/preempt.h
--- 25/include/linux/preempt.h~ppc64-spinlock-sleep-debugging 2004-02-11 21:15:05.000000000 -0800
+++ 25-akpm/include/linux/preempt.h 2004-02-11 21:15:05.000000000 -0800
@@ -24,6 +24,17 @@ do { \
extern void preempt_schedule(void);
+#define preempt_check_resched() \
+do { \
+ if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
+ preempt_schedule(); \
+} while (0)
+#else
+#define preempt_check_resched() do { } while (0)
+#endif
+
+#if defined(CONFIG_PREEMPT) || defined(CONFIG_DEBUG_SPINLOCK_SLEEP)
+
#define preempt_disable() \
do { \
inc_preempt_count(); \
@@ -36,12 +47,6 @@ do { \
dec_preempt_count(); \
} while (0)
-#define preempt_check_resched() \
-do { \
- if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
- preempt_schedule(); \
-} while (0)
-
#define preempt_enable() \
do { \
preempt_enable_no_resched(); \
diff -puN kernel/sched.c~ppc64-spinlock-sleep-debugging kernel/sched.c
--- 25/kernel/sched.c~ppc64-spinlock-sleep-debugging 2004-02-11 21:15:05.000000000 -0800
+++ 25-akpm/kernel/sched.c 2004-02-11 21:15:05.000000000 -0800
@@ -728,7 +728,7 @@ void sched_fork(task_t *p)
INIT_LIST_HEAD(&p->run_list);
p->array = NULL;
spin_lock_init(&p->switch_lock);
-#ifdef CONFIG_PREEMPT
+#if defined(CONFIG_PREEMPT) || defined(CONFIG_DEBUG_SPINLOCK_SLEEP)
/*
* During context-switch we hold precisely one spinlock, which
* schedule_tail drops. (in the common case it's this_rq()->lock,
@@ -2669,7 +2669,7 @@ void __init init_idle(task_t *idle, int
local_irq_restore(flags);
/* Set the preempt count _outside_ the spinlocks! */
-#ifdef CONFIG_PREEMPT
+#if defined(CONFIG_PREEMPT) || defined(CONFIG_DEBUG_SPINLOCK_SLEEP)
idle->thread_info->preempt_count = (idle->lock_depth >= 0);
#else
idle->thread_info->preempt_count = 0;
_