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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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