From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756893Ab3JHKnj (ORCPT ); Tue, 8 Oct 2013 06:43:39 -0400 Received: from merlin.infradead.org ([205.233.59.134]:33587 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755596Ab3JHKkx (ORCPT ); Tue, 8 Oct 2013 06:40:53 -0400 Message-Id: <20131008103830.347463501@infradead.org> User-Agent: quilt/0.60-1 Date: Tue, 08 Oct 2013 12:25:10 +0200 From: Peter Zijlstra To: Oleg Nesterov , Paul McKenney Cc: Mel Gorman , Rik van Riel , Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Thomas Gleixner , Steven Rostedt , Linus Torvalds , linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [PATCH 5/6] rcusync: Add the CONFIG_PROVE_RCU checks References: <20131008102505.404025673@infradead.org> Content-Disposition: inline; filename=oleg_nesterov-2_rcusync-add_the_config_prove_rcu_checks.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Suggested-by: "Paul E. McKenney" Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131004184633.GA17557@redhat.com --- include/linux/rcusync.h | 6 ++++++ kernel/rcusync.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/rcusync.c +++ b/kernel/rcusync.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));