From c3422bea5f09b0e85704f51f2b01271630b8940b Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 13 Sep 2009 09:15:10 -0700 Subject: rcu: Simplify rcu_read_unlock_special() quiescent-state accounting The earlier approach required two scheduling-clock ticks to note an preemptable-RCU quiescent state in the situation in which the scheduling-clock interrupt is unlucky enough to always interrupt an RCU read-side critical section. With this change, the quiescent state is instead noted by the outermost rcu_read_unlock() immediately following the first scheduling-clock tick, or, alternatively, by the first subsequent context switch. Therefore, this change also speeds up grace periods. Suggested-by: Josh Triplett Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu LKML-Reference: <12528585111945-git-send-email-> Signed-off-by: Ingo Molnar --- include/linux/sched.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index f3d74bd04d1..c62a9f84d61 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1740,7 +1740,6 @@ extern cputime_t task_gtime(struct task_struct *p); #define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */ #define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */ -#define RCU_READ_UNLOCK_GOT_QS (1 << 2) /* CPU has responded to RCU core. */ static inline void rcu_copy_process(struct task_struct *p) { -- cgit v1.2.3 From 16e3081191837a6a04733de5cd5d1d1b303140d4 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 13 Sep 2009 09:15:11 -0700 Subject: rcu: Fix synchronize_rcu() for TREE_PREEMPT_RCU The redirection of synchronize_sched() to synchronize_rcu() was appropriate for TREE_RCU, but not for TREE_PREEMPT_RCU. Fix this by creating an underlying synchronize_sched(). TREE_RCU then redirects synchronize_rcu() to synchronize_sched(), while TREE_PREEMPT_RCU has its own version of synchronize_rcu(). Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu LKML-Reference: <12528585111916-git-send-email-> Signed-off-by: Ingo Molnar --- include/linux/rcupdate.h | 23 +++++------------------ include/linux/rcutree.h | 4 ++-- 2 files changed, 7 insertions(+), 20 deletions(-) (limited to 'include/linux') diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 95e0615f4d7..39dce83c486 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -52,8 +52,13 @@ struct rcu_head { }; /* Exported common interfaces */ +#ifdef CONFIG_TREE_PREEMPT_RCU extern void synchronize_rcu(void); +#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ +#define synchronize_rcu synchronize_sched +#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ extern void synchronize_rcu_bh(void); +extern void synchronize_sched(void); extern void rcu_barrier(void); extern void rcu_barrier_bh(void); extern void rcu_barrier_sched(void); @@ -261,24 +266,6 @@ struct rcu_synchronize { extern void wakeme_after_rcu(struct rcu_head *head); -/** - * synchronize_sched - block until all CPUs have exited any non-preemptive - * kernel code sequences. - * - * This means that all preempt_disable code sequences, including NMI and - * hardware-interrupt handlers, in progress on entry will have completed - * before this primitive returns. However, this does not guarantee that - * softirq handlers will have completed, since in some kernels, these - * handlers can run in process context, and can block. - * - * This primitive provides the guarantees made by the (now removed) - * synchronize_kernel() API. In contrast, synchronize_rcu() only - * guarantees that rcu_read_lock() sections will have completed. - * In "classic RCU", these two guarantees happen to be one and - * the same, but can differ in realtime RCU implementations. - */ -#define synchronize_sched() __synchronize_sched() - /** * call_rcu - Queue an RCU callback for invocation after a grace period. * @head: structure to be used for queueing the RCU updates. diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index a8930771782..00d08c0cbcc 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -53,6 +53,8 @@ static inline void __rcu_read_unlock(void) preempt_enable(); } +#define __synchronize_sched() synchronize_rcu() + static inline void exit_rcu(void) { } @@ -68,8 +70,6 @@ static inline void __rcu_read_unlock_bh(void) local_bh_enable(); } -#define __synchronize_sched() synchronize_rcu() - extern void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); -- cgit v1.2.3 From a71fca58b7f4abca551ae2256ac08dd9123a03f9 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 18 Sep 2009 10:28:19 -0700 Subject: rcu: Fix whitespace inconsistencies Fix a number of whitespace ^Ierrors in the include/linux/rcu* and the kernel/rcu* files. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu LKML-Reference: <20090918172819.GA24405@linux.vnet.ibm.com> [ did more checkpatch fixlets ] Signed-off-by: Ingo Molnar --- include/linux/rculist_nulls.h | 2 +- include/linux/rcupdate.h | 6 +++--- include/linux/rcutree.h | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h index f9ddd03961a..589a40919f0 100644 --- a/include/linux/rculist_nulls.h +++ b/include/linux/rculist_nulls.h @@ -102,7 +102,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n, */ #define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \ for (pos = rcu_dereference((head)->first); \ - (!is_a_nulls(pos)) && \ + (!is_a_nulls(pos)) && \ ({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \ pos = rcu_dereference(pos->next)) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 39dce83c486..6fe0363724e 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -1,5 +1,5 @@ /* - * Read-Copy Update mechanism for mutual exclusion + * Read-Copy Update mechanism for mutual exclusion * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -18,7 +18,7 @@ * Copyright IBM Corporation, 2001 * * Author: Dipankar Sarma - * + * * Based on the original work by Paul McKenney * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. * Papers: @@ -26,7 +26,7 @@ * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) * * For detailed explanation of Read-Copy Update mechanism see - - * http://lse.sourceforge.net/locking/rcupdate.html + * http://lse.sourceforge.net/locking/rcupdate.html * */ diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 00d08c0cbcc..37682770e9d 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -24,7 +24,7 @@ * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. * * For detailed explanation of Read-Copy Update mechanism see - - * Documentation/RCU + * Documentation/RCU */ #ifndef __LINUX_RCUTREE_H -- cgit v1.2.3