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    Subject[PATCH RFC tip/core/rcu 14/28] rcu: Warn when rcu_read_lock() is used in extended quiescent state
    Date
    From: Frederic Weisbecker <fweisbec@gmail.com>

    We are currently able to detect uses of rcu_dereference_check() inside
    extended quiescent states (such as the RCU-free window in idle).
    But rcu_read_lock() and friends can be used without rcu_dereference(),
    so that the earlier commit checking for use of rcu_dereference() and
    friends while in RCU idle mode miss some error conditions. This commit
    therefore adds extended quiescent state checking to rcu_read_lock() and
    friends.

    Uses of RCU from within RCU-idle mode are totally ignored by
    RCU, hence the importance of these checks.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    ---
    include/linux/rcupdate.h | 52 +++++++++++++++++++++++++++++++++++++--------
    1 files changed, 42 insertions(+), 10 deletions(-)

    diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
    index bf91fcf..d201c15 100644
    --- a/include/linux/rcupdate.h
    +++ b/include/linux/rcupdate.h
    @@ -237,21 +237,53 @@ static inline int rcu_is_cpu_idle(void)
    }
    #endif /* else !CONFIG_PROVE_RCU */

    +static inline void rcu_lock_acquire(struct lockdep_map *map)
    +{
    + WARN_ON_ONCE(rcu_is_cpu_idle());
    + lock_acquire(map, 0, 0, 2, 1, NULL, _THIS_IP_);
    +}
    +
    +static inline void rcu_lock_release(struct lockdep_map *map)
    +{
    + WARN_ON_ONCE(rcu_is_cpu_idle());
    + lock_release(map, 1, _THIS_IP_);
    +}
    +
    extern struct lockdep_map rcu_lock_map;
    -# define rcu_read_acquire() \
    - lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
    -# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
    +
    +static inline void rcu_read_acquire(void)
    +{
    + rcu_lock_acquire(&rcu_lock_map);
    +}
    +
    +static inline void rcu_read_release(void)
    +{
    + rcu_lock_release(&rcu_lock_map);
    +}

    extern struct lockdep_map rcu_bh_lock_map;
    -# define rcu_read_acquire_bh() \
    - lock_acquire(&rcu_bh_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
    -# define rcu_read_release_bh() lock_release(&rcu_bh_lock_map, 1, _THIS_IP_)
    +
    +static inline void rcu_read_acquire_bh(void)
    +{
    + rcu_lock_acquire(&rcu_bh_lock_map);
    +}
    +
    +static inline void rcu_read_release_bh(void)
    +{
    + rcu_lock_release(&rcu_bh_lock_map);
    +}

    extern struct lockdep_map rcu_sched_lock_map;
    -# define rcu_read_acquire_sched() \
    - lock_acquire(&rcu_sched_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
    -# define rcu_read_release_sched() \
    - lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
    +
    +static inline void rcu_read_acquire_sched(void)
    +{
    + rcu_lock_acquire(&rcu_sched_lock_map);
    +}
    +
    +static inline void rcu_read_release_sched(void)
    +{
    + rcu_lock_release(&rcu_sched_lock_map);
    +}

    extern int debug_lockdep_rcu_enabled(void);

    --
    1.7.3.2


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