From: Oleg Nesterov It would be nice to validate that the caller of rcu_sync_is_idle() holds the corresponding type of RCU read-side lock. Add the new rcu_sync_ops->held() method and change rcu_sync_is_idle() to WARN() if it returns false. This obviously penalizes the readers (fast-path), but only if CONFIG_PROVE_RCU. Reviewed-by: Paul E. McKenney Suggested-by: "Paul E. McKenney" Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) --- include/linux/rcusync.h | 6 ++++++ kernel/rcu/sync.c | 21 +++++++++++++++++++++ 2 files changed, 27 insertions(+) --- a/include/linux/rcusync.h +++ b/include/linux/rcusync.h @@ -17,9 +17,15 @@ struct rcu_sync_struct { enum rcu_sync_type gp_type; }; +extern bool __rcu_sync_is_idle(struct rcu_sync_struct *); + static inline bool rcu_sync_is_idle(struct rcu_sync_struct *rss) { +#ifdef CONFIG_PROVE_RCU + return __rcu_sync_is_idle(rss); +#else return !rss->gp_state; /* GP_IDLE */ +#endif } extern void rcu_sync_init(struct rcu_sync_struct *, enum rcu_sync_type); --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -1,21 +1,33 @@ #include #include +#ifdef CONFIG_PROVE_RCU +#define __INIT_HELD(func) .held = func, +#else +#define __INIT_HELD(func) +#endif + static const struct { void (*sync)(void); void (*call)(struct rcu_head *, void (*)(struct rcu_head *)); +#ifdef CONFIG_PROVE_RCU + int (*held)(void); +#endif } gp_ops[] = { [RCU_SYNC] = { .sync = synchronize_rcu, .call = call_rcu, + __INIT_HELD(rcu_read_lock_held) }, [RCU_SCHED_SYNC] = { .sync = synchronize_sched, .call = call_rcu_sched, + __INIT_HELD(rcu_read_lock_sched_held) }, [RCU_BH_SYNC] = { .sync = synchronize_rcu_bh, .call = call_rcu_bh, + __INIT_HELD(rcu_read_lock_bh_held) }, }; @@ -24,6 +36,15 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLA #define rss_lock gp_wait.lock +#ifdef CONFIG_PROVE_RCU +bool __rcu_sync_is_idle(struct rcu_sync_struct *rss) +{ + WARN_ON(!gp_ops[rss->gp_type].held()); + return rss->gp_state == GP_IDLE; +} +EXPORT_SYMBOL_GPL(__rcu_sync_is_idle); +#endif + void rcu_sync_init(struct rcu_sync_struct *rss, enum rcu_sync_type type) { memset(rss, 0, sizeof(*rss)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/