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Subject[PATCH 1/3] kernel.h: sched: introduce might_sleep_disabled()
Since commit [5342e269: rcu: Permit rt_mutex_unlock() with
irqs disabled], rt_mutex_lock() could be called with irqs
disabled and it will call might_sleep() unconditionally.
To prevent this kind of false positive, introduce
might_sleep_disabled() which will be used in later patch.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---
include/linux/kernel.h | 25 +++++++++++++++++++++----
include/linux/sched.h | 14 +++++++-------
kernel/sched.c | 6 ++++--
3 files changed, 32 insertions(+), 13 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index e8b1597..deaba68 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -130,7 +130,8 @@ extern int _cond_resched(void);
#endif

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
- void __might_sleep(const char *file, int line, int preempt_offset);
+ void __might_sleep(const char *file, int line, int preempt_offset,
+ bool warn_irqs);
/**
* might_sleep - annotation for functions that can sleep
*
@@ -141,12 +142,28 @@ extern int _cond_resched(void);
* be bitten later when the calling function happens to sleep when it is not
* supposed to.
*/
-# define might_sleep() \
- do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
+# define might_sleep() \
+ do { \
+ __might_sleep(__FILE__, __LINE__, 0, true); \
+ might_resched(); } \
+ while (0)
+
+/*
+ * Special version of might_sleep() which don't warn when called
+ * with irq disabled. Will be used in rt_mutex_lock() which
+ * could be called with irq disabled.
+ */
+# define might_sleep_irqdisabled() \
+ do { \
+ __might_sleep(__FILE__, __LINE__, 0, false); \
+ might_resched(); } \
+ while (0)
+
#else
static inline void __might_sleep(const char *file, int line,
- int preempt_offset) { }
+ int preempt_offset, bool warn_irqs) { }
# define might_sleep() do { might_resched(); } while (0)
+# define might_sleep_irqdisabled() do { might_resched(); } while (0)
#endif

#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4a7e4d3..d077c62 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2534,9 +2534,9 @@ static inline int need_resched(void)
*/
extern int _cond_resched(void);

-#define cond_resched() ({ \
- __might_sleep(__FILE__, __LINE__, 0); \
- _cond_resched(); \
+#define cond_resched() ({ \
+ __might_sleep(__FILE__, __LINE__, 0, true); \
+ _cond_resched(); \
})

extern int __cond_resched_lock(spinlock_t *lock);
@@ -2547,15 +2547,15 @@ extern int __cond_resched_lock(spinlock_t *lock);
#define PREEMPT_LOCK_OFFSET 0
#endif

-#define cond_resched_lock(lock) ({ \
- __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
- __cond_resched_lock(lock); \
+#define cond_resched_lock(lock) ({ \
+ __might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET, true); \
+ __cond_resched_lock(lock); \
})

extern int __cond_resched_softirq(void);

#define cond_resched_softirq() ({ \
- __might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET); \
+ __might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET, true);\
__cond_resched_softirq(); \
})

diff --git a/kernel/sched.c b/kernel/sched.c
index 0e9344a..ce24450 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8363,12 +8363,14 @@ static inline int preempt_count_equals(int preempt_offset)
return (nested == preempt_offset);
}

-void __might_sleep(const char *file, int line, int preempt_offset)
+void __might_sleep(const char *file, int line, int preempt_offset,
+ bool warn_irqs)
{
static unsigned long prev_jiffy; /* ratelimiting */

rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */
- if ((preempt_count_equals(preempt_offset) && !irqs_disabled()) ||
+ if ((preempt_count_equals(preempt_offset) &&
+ (warn_irqs ? !irqs_disabled() : 1)) ||
system_state != SYSTEM_RUNNING || oops_in_progress)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
--
1.7.5.4


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