From: Oleg Nesterov <[email protected]> This commit validates that the caller of rcu_sync_is_idle() holds the corresponding type of RCU read-side lock, but only in kernels built with CONFIG_PROVE_RCU=y. This validation is carried out via a new rcu_sync_ops->held() method that is checked within rcu_sync_is_idle().
Note that although this does add code to the fast path, it only does so in kernels built with CONFIG_PROVE_RCU=y. Suggested-by: "Paul E. McKenney" <[email protected]> Signed-off-by: Oleg Nesterov <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- include/linux/rcu_sync.h | 6 ++++++ kernel/rcu/sync.c | 20 ++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h index c6d2272c4459..1f2d4fc30b04 100644 --- a/include/linux/rcu_sync.h +++ b/include/linux/rcu_sync.h @@ -40,6 +40,8 @@ struct rcu_sync { enum rcu_sync_type gp_type; }; +extern bool __rcu_sync_is_idle(struct rcu_sync *); + /** * rcu_sync_is_idle() - Are readers permitted to use their fastpaths? * @rsp: Pointer to rcu_sync structure to use for synchronization @@ -50,7 +52,11 @@ struct rcu_sync { */ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) { +#ifdef CONFIG_PROVE_RCU + return __rcu_sync_is_idle(rsp); +#else return !rsp->gp_state; /* GP_IDLE */ +#endif } extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type); diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c index 5a9aa4c394f1..01c9807a7f73 100644 --- a/kernel/rcu/sync.c +++ b/kernel/rcu/sync.c @@ -23,21 +23,33 @@ #include <linux/rcu_sync.h> #include <linux/sched.h> +#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) }, }; @@ -46,6 +58,14 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY }; #define rss_lock gp_wait.lock +#ifdef CONFIG_PROVE_RCU +bool __rcu_sync_is_idle(struct rcu_sync *rsp) +{ + WARN_ON(!gp_ops[rsp->gp_type].held()); + return rsp->gp_state == GP_IDLE; +} +#endif + /** * rcu_sync_init() - Initialize an rcu_sync structure * @rsp: Pointer to rcu_sync structure to be initialized -- 2.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
