On Fri, Sep 11, 2015 at 05:59:18PM +0200, Oleg Nesterov wrote:
> 1. Rename __rcu_sync_is_idle() to rcu_sync_lockdep_assert() and
> change it to use rcu_lockdep_assert().
>
> 2. Change rcu_sync_is_idle() to return rsp->gp_state == GP_IDLE
> unconditonally, this way we can remove the same check from
> rcu_sync_lockdep_assert() and clearly isolate the debugging
> code.
>
> Note: rcu_sync_enter()->wait_event(gp_state == GP_PASSED) needs
> another CONFIG_PROVE_RCU check, the same we do in ->sync(); but
> this needs some simple preparations in the core RCU code to avoid
> the code duplication.
>
> Signed-off-by: Oleg Nesterov <[email protected]>
Queued for v4.4, thank you, Oleg!
Thanx, Paul
> ---
> include/linux/rcu_sync.h | 7 +++----
> kernel/rcu/sync.c | 6 +++---
> 2 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
> index 8069d64..a63a33e 100644
> --- a/include/linux/rcu_sync.h
> +++ b/include/linux/rcu_sync.h
> @@ -40,7 +40,7 @@ struct rcu_sync {
> enum rcu_sync_type gp_type;
> };
>
> -extern bool __rcu_sync_is_idle(struct rcu_sync *);
> +extern void rcu_sync_lockdep_assert(struct rcu_sync *);
>
> /**
> * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
> @@ -53,10 +53,9 @@ extern bool __rcu_sync_is_idle(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 */
> + rcu_sync_lockdep_assert(rsp);
> #endif
> + return !rsp->gp_state; /* GP_IDLE */
> }
>
> 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 1c73c57..a8cf199 100644
> --- a/kernel/rcu/sync.c
> +++ b/kernel/rcu/sync.c
> @@ -63,10 +63,10 @@ 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)
> +void rcu_sync_lockdep_assert(struct rcu_sync *rsp)
> {
> - WARN_ON(!gp_ops[rsp->gp_type].held());
> - return rsp->gp_state == GP_IDLE;
> + rcu_lockdep_assert(gp_ops[rsp->gp_type].held(),
> + "suspicious rcu_sync_is_idle() usage");
> }
> #endif
>
> --
> 1.5.5.1
>
>
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