Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933720AbXHGSs2 (ORCPT ); Tue, 7 Aug 2007 14:48:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751707AbXHGSsS (ORCPT ); Tue, 7 Aug 2007 14:48:18 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:42943 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751521AbXHGSsP (ORCPT ); Tue, 7 Aug 2007 14:48:15 -0400 Date: Tue, 7 Aug 2007 11:48:12 -0700 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: linux-rt-users@vger.kernel.org, mingo@elte.hu, akpm@linux-foundation.org, dipankar@in.ibm.com, josht@linux.vnet.ibm.com, tytso@us.ibm.com, dvhltc@us.ibm.com, tglx@linutronix.de Subject: [PATCH 3/4 RFC] RCU: preemptible RCU Message-ID: <20070807184812.GC10068@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20070807183946.GA32110@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070807183946.GA32110@linux.vnet.ibm.com> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 47314 Lines: 1483 This patch implements a new version of RCU which allows its read-side critical sections to be preempted. It uses a set of counter pairs to keep track of the read-side critical sections and flips them when all tasks exit read-side critical section. The details of this implementation can be found in this paper - http://www.rdrop.com/users/paulmck/RCU/OLSrtRCU.2006.08.11a.pdf This patch was developed as a part of the -rt kernel development and meant to provide better latencies when read-side critical sections of RCU don't disable preemption. As a consequence of keeping track of RCU readers, the readers have a slight overhead (optimizations in the paper). This implementation co-exists with the "classic" RCU implementations and can be switched to at compiler. Also includes RCU tracing summarized in debugfs and RCU_SOFTIRQ for the preemptible variant of RCU. Signed-off-by: Dipankar Sarma Signed-off-by: Steven Rostedt (for RCU_SOFTIRQ) Signed-off-by: Paul McKenney --- include/linux/interrupt.h | 1 include/linux/rcuclassic.h | 2 include/linux/rcupdate.h | 7 include/linux/rcupreempt.h | 78 +++ include/linux/rcupreempt_trace.h | 100 +++++ include/linux/sched.h | 5 kernel/Kconfig.preempt | 38 + kernel/Makefile | 7 kernel/fork.c | 4 kernel/rcupreempt.c | 768 +++++++++++++++++++++++++++++++++++++++ kernel/rcupreempt_trace.c | 330 ++++++++++++++++ 11 files changed, 1337 insertions(+), 3 deletions(-) diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/interrupt.h linux-2.6.22-c-preemptrcu/include/linux/interrupt.h --- linux-2.6.22-b-fixbarriers/include/linux/interrupt.h 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/include/linux/interrupt.h 2007-07-21 11:16:29.000000000 -0700 @@ -269,6 +269,7 @@ enum #ifdef CONFIG_HIGH_RES_TIMERS HRTIMER_SOFTIRQ, #endif + RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */ }; /* softirq mask and active fields moved to irq_cpustat_t in diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/rcuclassic.h linux-2.6.22-c-preemptrcu/include/linux/rcuclassic.h --- linux-2.6.22-b-fixbarriers/include/linux/rcuclassic.h 2007-07-19 14:19:00.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/include/linux/rcuclassic.h 2007-07-21 08:51:53.000000000 -0700 @@ -142,8 +142,6 @@ extern int rcu_needs_cpu(int cpu); extern void __rcu_init(void); extern void rcu_check_callbacks(int cpu, int user); extern void rcu_restart_cpu(int cpu); -extern long rcu_batches_completed(void); -extern long rcu_batches_completed_bh(void); #endif /* __KERNEL__ */ #endif /* __LINUX_RCUCLASSIC_H */ diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/rcupdate.h linux-2.6.22-c-preemptrcu/include/linux/rcupdate.h --- linux-2.6.22-b-fixbarriers/include/linux/rcupdate.h 2007-07-19 14:02:36.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/include/linux/rcupdate.h 2007-07-21 12:29:29.000000000 -0700 @@ -52,7 +52,11 @@ struct rcu_head { void (*func)(struct rcu_head *head); }; +#ifdef CONFIG_CLASSIC_RCU #include +#else /* #ifdef CONFIG_CLASSIC_RCU */ +#include +#endif /* #else #ifdef CONFIG_CLASSIC_RCU */ #define RCU_HEAD_INIT { .next = NULL, .func = NULL } #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT @@ -218,10 +222,13 @@ extern void FASTCALL(call_rcu_bh(struct /* Exported common interfaces */ extern void synchronize_rcu(void); extern void rcu_barrier(void); +extern long rcu_batches_completed(void); +extern long rcu_batches_completed_bh(void); /* Internal to kernel */ extern void rcu_init(void); extern void rcu_check_callbacks(int cpu, int user); +extern int rcu_needs_cpu(int cpu); #endif /* __KERNEL__ */ #endif /* __LINUX_RCUPDATE_H */ diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/rcupreempt.h linux-2.6.22-c-preemptrcu/include/linux/rcupreempt.h --- linux-2.6.22-b-fixbarriers/include/linux/rcupreempt.h 1969-12-31 16:00:00.000000000 -0800 +++ linux-2.6.22-c-preemptrcu/include/linux/rcupreempt.h 2007-07-21 15:54:55.000000000 -0700 @@ -0,0 +1,78 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (RT implementation) + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2006 + * + * Author: Paul McKenney + * + * Based on the original work by Paul McKenney + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU + * + */ + +#ifndef __LINUX_RCUPREEMPT_H +#define __LINUX_RCUPREEMPT_H + +#ifdef __KERNEL__ + +#include +#include +#include +#include +#include +#include + +#define rcu_qsctr_inc(cpu) +#define rcu_bh_qsctr_inc(cpu) +#define call_rcu_bh(head, rcu) call_rcu(head, rcu) + +extern void __rcu_read_lock(void); +extern void __rcu_read_unlock(void); +extern int rcu_pending(int cpu); +extern int rcu_needs_cpu(int cpu); + +#define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } +#define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } + +#define __rcu_read_lock_nesting() (current->rcu_read_lock_nesting) + +extern void __synchronize_sched(void); + +extern void __rcu_init(void); +extern void rcu_check_callbacks(int cpu, int user); +extern void rcu_restart_cpu(int cpu); + +#ifdef CONFIG_RCU_TRACE +struct rcupreempt_trace; +extern int *rcupreempt_flipctr(int cpu); +extern long rcupreempt_data_completed(void); +extern int rcupreempt_flip_flag(int cpu); +extern int rcupreempt_mb_flag(int cpu); +extern char *rcupreempt_try_flip_state_name(void); +extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); +#endif + +struct softirq_action; + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUPREEMPT_H */ diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/rcupreempt_trace.h linux-2.6.22-c-preemptrcu/include/linux/rcupreempt_trace.h --- linux-2.6.22-b-fixbarriers/include/linux/rcupreempt_trace.h 1969-12-31 16:00:00.000000000 -0800 +++ linux-2.6.22-c-preemptrcu/include/linux/rcupreempt_trace.h 2007-07-21 10:06:02.000000000 -0700 @@ -0,0 +1,100 @@ +/* + * Read-Copy Update mechanism for mutual exclusion (RT implementation) + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2006 + * + * Author: Paul McKenney + * + * Based on the original work by Paul McKenney + * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. + * Papers: + * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf + * 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 + * + */ + +#ifndef __LINUX_RCUPREEMPT_TRACE_H +#define __LINUX_RCUPREEMPT_TRACE_H + +#ifdef __KERNEL__ +#include +#include + +#include + +/* + * PREEMPT_RCU data structures. + */ + +struct rcupreempt_trace { + long next_length; + long next_add; + long wait_length; + long wait_add; + long done_length; + long done_add; + long done_remove; + atomic_t done_invoked; + long rcu_check_callbacks; + atomic_t rcu_try_flip_1; + atomic_t rcu_try_flip_e1; + long rcu_try_flip_i1; + long rcu_try_flip_ie1; + long rcu_try_flip_g1; + long rcu_try_flip_a1; + long rcu_try_flip_ae1; + long rcu_try_flip_a2; + long rcu_try_flip_z1; + long rcu_try_flip_ze1; + long rcu_try_flip_z2; + long rcu_try_flip_m1; + long rcu_try_flip_me1; + long rcu_try_flip_m2; +}; + +#ifdef CONFIG_RCU_TRACE +#define RCU_TRACE(fn, arg) fn(arg); +#else +#define RCU_TRACE(fn, arg) +#endif + +extern void rcupreempt_trace_move2done(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_invoke(struct rcupreempt_trace *trace); +extern void rcupreempt_trace_next_add(struct rcupreempt_trace *trace); + +#endif /* __KERNEL__ */ +#endif /* __LINUX_RCUPREEMPT_TRACE_H */ diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/include/linux/sched.h linux-2.6.22-c-preemptrcu/include/linux/sched.h --- linux-2.6.22-b-fixbarriers/include/linux/sched.h 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/include/linux/sched.h 2007-07-21 09:12:49.000000000 -0700 @@ -850,6 +850,11 @@ struct task_struct { cpumask_t cpus_allowed; unsigned int time_slice, first_time_slice; +#ifdef CONFIG_PREEMPT_RCU + int rcu_read_lock_nesting; + int rcu_flipctr_idx; +#endif /* #ifdef CONFIG_PREEMPT_RCU */ + #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/kernel/fork.c linux-2.6.22-c-preemptrcu/kernel/fork.c --- linux-2.6.22-b-fixbarriers/kernel/fork.c 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/kernel/fork.c 2007-07-21 09:23:20.000000000 -0700 @@ -1032,6 +1032,10 @@ static struct task_struct *copy_process( INIT_LIST_HEAD(&p->children); INIT_LIST_HEAD(&p->sibling); +#ifdef CONFIG_PREEMPT_RCU + p->rcu_read_lock_nesting = 0; + p->rcu_flipctr_idx = 0; +#endif /* #ifdef CONFIG_PREEMPT_RCU */ p->vfork_done = NULL; spin_lock_init(&p->alloc_lock); diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/kernel/Kconfig.preempt linux-2.6.22-c-preemptrcu/kernel/Kconfig.preempt --- linux-2.6.22-b-fixbarriers/kernel/Kconfig.preempt 2007-07-08 16:32:17.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/kernel/Kconfig.preempt 2007-07-21 10:11:00.000000000 -0700 @@ -63,3 +63,41 @@ config PREEMPT_BKL Say Y here if you are building a kernel for a desktop system. Say N if you are unsure. +choice + prompt "RCU implementation type:" + default CLASSIC_RCU + +config CLASSIC_RCU + bool "Classic RCU" + help + This option selects the classic RCU implementation that is + designed for best read-side performance on non-realtime + systems. + + Say Y if you are unsure. + +config PREEMPT_RCU + bool "Preemptible RCU" + depends on PREEMPT + help + This option reduces the latency of the kernel by making certain + RCU sections preemptible. Normally RCU code is non-preemptible, if + this option is selected then read-only RCU sections become + preemptible. This helps latency, but may expose bugs due to + now-naive assumptions about each RCU read-side critical section + remaining on a given CPU through its execution. + + Say N if you are unsure. + +endchoice + +config RCU_TRACE + bool "Enable tracing for RCU - currently stats in debugfs" + select DEBUG_FS + default y + help + This option provides tracing in RCU which presents stats + in debugfs for debugging RCU implementation. + + Say Y here if you want to enable RCU tracing + Say N if you are unsure. diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/kernel/Makefile linux-2.6.22-c-preemptrcu/kernel/Makefile --- linux-2.6.22-b-fixbarriers/kernel/Makefile 2007-07-19 12:16:03.000000000 -0700 +++ linux-2.6.22-c-preemptrcu/kernel/Makefile 2007-07-21 10:50:35.000000000 -0700 @@ -6,7 +6,7 @@ obj-y = sched.o fork.o exec_domain.o exit.o itimer.o time.o softirq.o resource.o \ sysctl.o capability.o ptrace.o timer.o user.o \ signal.o sys.o kmod.o workqueue.o pid.o \ - rcupdate.o rcuclassic.o extable.o params.o posix-timers.o \ + rcupdate.o extable.o params.o posix-timers.o \ kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \ hrtimer.o rwsem.o latency.o nsproxy.o srcu.o die_notifier.o @@ -46,6 +46,11 @@ obj-$(CONFIG_DETECT_SOFTLOCKUP) += softl obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ obj-$(CONFIG_SECCOMP) += seccomp.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o +obj-$(CONFIG_CLASSIC_RCU) += rcuclassic.o +obj-$(CONFIG_PREEMPT_RCU) += rcupreempt.o +ifeq ($(CONFIG_PREEMPT_RCU),y) +obj-$(CONFIG_RCU_TRACE) += rcupreempt_trace.o +endif obj-$(CONFIG_RELAY) += relay.o obj-$(CONFIG_SYSCTL) += utsname_sysctl.o obj-$(CONFIG_UTS_NS) += utsname.o diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/kernel/rcupreempt.c linux-2.6.22-c-preemptrcu/kernel/rcupreempt.c --- linux-2.6.22-b-fixbarriers/kernel/rcupreempt.c 1969-12-31 16:00:00.000000000 -0800 +++ linux-2.6.22-c-preemptrcu/kernel/rcupreempt.c 2007-07-21 15:54:15.000000000 -0700 @@ -0,0 +1,768 @@ +/* + * Read-Copy Update mechanism for mutual exclusion, realtime implementation + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright IBM Corporation, 2006 + * + * Authors: Paul E. McKenney + * With thanks to Esben Nielsen, Bill Huey, and Ingo Molnar + * for pushing me away from locks and towards counters, and + * to Suparna Bhattacharya for pushing me completely away + * from atomic instructions on the read side. + * + * Papers: http://www.rdrop.com/users/paulmck/RCU + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU/ *.txt + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * PREEMPT_RCU data structures. + */ + +#define GP_STAGES 4 +struct rcu_data { + spinlock_t lock; + long completed; /* Number of last completed batch. */ + int waitlistcount; + struct tasklet_struct rcu_tasklet; + struct rcu_head *nextlist; + struct rcu_head **nexttail; + struct rcu_head *waitlist[GP_STAGES]; + struct rcu_head **waittail[GP_STAGES]; + struct rcu_head *donelist; + struct rcu_head **donetail; +#ifdef CONFIG_RCU_TRACE + struct rcupreempt_trace trace; +#endif /* #ifdef CONFIG_RCU_TRACE */ +}; +struct rcu_ctrlblk { + spinlock_t fliplock; + long completed; /* Number of last completed batch. */ +}; +static DEFINE_PER_CPU(struct rcu_data, rcu_data); +static struct rcu_ctrlblk rcu_ctrlblk = { + .fliplock = SPIN_LOCK_UNLOCKED, + .completed = 0, +}; +static DEFINE_PER_CPU(int [2], rcu_flipctr) = { 0, 0 }; + +/* + * States for rcu_try_flip() and friends. + */ + +enum rcu_try_flip_states { + rcu_try_flip_idle_state, /* "I" */ + rcu_try_flip_waitack_state, /* "A" */ + rcu_try_flip_waitzero_state, /* "Z" */ + rcu_try_flip_waitmb_state /* "M" */ +}; +static enum rcu_try_flip_states rcu_try_flip_state = rcu_try_flip_idle_state; +#ifdef CONFIG_RCU_TRACE +static char *rcu_try_flip_state_names[] = + { "idle", "waitack", "waitzero", "waitmb" }; +#endif /* #ifdef CONFIG_RCU_TRACE */ + +/* + * Enum and per-CPU flag to determine when each CPU has seen + * the most recent counter flip. + */ + +enum rcu_flip_flag_values { + rcu_flip_seen, /* Steady/initial state, last flip seen. */ + /* Only GP detector can update. */ + rcu_flipped /* Flip just completed, need confirmation. */ + /* Only corresponding CPU can update. */ +}; +static DEFINE_PER_CPU(enum rcu_flip_flag_values, rcu_flip_flag) = rcu_flip_seen; + +/* + * Enum and per-CPU flag to determine when each CPU has executed the + * needed memory barrier to fence in memory references from its last RCU + * read-side critical section in the just-completed grace period. + */ + +enum rcu_mb_flag_values { + rcu_mb_done, /* Steady/initial state, no mb()s required. */ + /* Only GP detector can update. */ + rcu_mb_needed /* Flip just completed, need an mb(). */ + /* Only corresponding CPU can update. */ +}; +static DEFINE_PER_CPU(enum rcu_mb_flag_values, rcu_mb_flag) = rcu_mb_done; + +/* + * Macro that prevents the compiler from reordering accesses, but does + * absolutely -nothing- to prevent CPUs from reordering. This is used + * only to mediate communication between mainline code and hardware + * interrupt and NMI handlers. + */ +#define ORDERED_WRT_IRQ(x) (*(volatile typeof(x) *)&(x)) + +/* + * RCU_DATA_ME: find the current CPU's rcu_data structure. + * RCU_DATA_CPU: find the specified CPU's rcu_data structure. + */ +#define RCU_DATA_ME() (&__get_cpu_var(rcu_data)) +#define RCU_DATA_CPU(cpu) (&per_cpu(rcu_data, cpu)) + +/* + * Helper macro for tracing when the appropriate rcu_data is not + * cached in a local variable, but where the CPU number is so cached. + */ +#define RCU_TRACE_CPU(f, cpu) RCU_TRACE(f, &(RCU_DATA_CPU(cpu)->trace)); + +/* + * Helper macro for tracing when the appropriate rcu_data is not + * cached in a local variable. + */ +#define RCU_TRACE_ME(f) RCU_TRACE(f, &(RCU_DATA_ME()->trace)); + +/* + * Helper macro for tracing when the appropriate rcu_data is pointed + * to by a local variable. + */ +#define RCU_TRACE_RDP(f, rdp) RCU_TRACE(f, &((rdp)->trace)); + +/* + * Return the number of RCU batches processed thus far. Useful + * for debug and statistics. + */ +long rcu_batches_completed(void) +{ + return rcu_ctrlblk.completed; +} + +/* + * Return the number of RCU batches processed thus far. Useful for debug + * and statistics. The _bh variant is identical to straight RCU. + */ +long rcu_batches_completed_bh(void) +{ + return rcu_ctrlblk.completed; +} + +void __rcu_read_lock(void) +{ + int idx; + struct task_struct *me = current; + int nesting; + + nesting = ORDERED_WRT_IRQ(me->rcu_read_lock_nesting); + if (nesting != 0) { + + /* An earlier rcu_read_lock() covers us, just count it. */ + + me->rcu_read_lock_nesting = nesting + 1; + + } else { + unsigned long oldirq; + + /* + * Disable local interrupts to prevent the grace-period + * detection state machine from seeing us half-done. + * NMIs can still occur, of course, and might themselves + * contain rcu_read_lock(). + */ + + local_irq_save(oldirq); + + /* + * Outermost nesting of rcu_read_lock(), so increment + * the current counter for the current CPU. Use volatile + * casts to prevent the compiler from reordering. + */ + + idx = ORDERED_WRT_IRQ(rcu_ctrlblk.completed) & 0x1; + smp_read_barrier_depends(); /* @@@@ might be unneeded */ + ORDERED_WRT_IRQ(__get_cpu_var(rcu_flipctr)[idx])++; + + /* + * Now that the per-CPU counter has been incremented, we + * are protected from races with rcu_read_lock() invoked + * from NMI handlers on this CPU. We can therefore safely + * increment the nesting counter, relieving further NMIs + * of the need to increment the per-CPU counter. + */ + + ORDERED_WRT_IRQ(me->rcu_read_lock_nesting) = nesting + 1; + + /* + * Now that we have preventing any NMIs from storing + * to the ->rcu_flipctr_idx, we can safely use it to + * remember which counter to decrement in the matching + * rcu_read_unlock(). + */ + + ORDERED_WRT_IRQ(me->rcu_flipctr_idx) = idx; + local_irq_restore(oldirq); + } +} + +void __rcu_read_unlock(void) +{ + int idx; + struct task_struct *me = current; + int nesting; + + nesting = ORDERED_WRT_IRQ(me->rcu_read_lock_nesting); + if (nesting > 1) { + + /* + * We are still protected by the enclosing rcu_read_lock(), + * so simply decrement the counter. + */ + + me->rcu_read_lock_nesting = nesting - 1; + + } else { + unsigned long oldirq; + + /* + * Disable local interrupts to prevent the grace-period + * detection state machine from seeing us half-done. + * NMIs can still occur, of course, and might themselves + * contain rcu_read_lock() and rcu_read_unlock(). + */ + + local_irq_save(oldirq); + + /* + * Outermost nesting of rcu_read_unlock(), so we must + * decrement the current counter for the current CPU. + * This must be done carefully, because NMIs can + * occur at any point in this code, and any rcu_read_lock() + * and rcu_read_unlock() pairs in the NMI handlers + * must interact non-destructively with this code. + * Lots of volatile casts, and -very- careful ordering. + * + * Changes to this code, including this one, must be + * inspected, validated, and tested extremely carefully!!! + */ + + /* + * First, pick up the index. Enforce ordering for + * DEC Alpha. + */ + + idx = ORDERED_WRT_IRQ(me->rcu_flipctr_idx); + smp_read_barrier_depends(); /* @@@ Needed??? */ + + /* + * Now that we have fetched the counter index, it is + * safe to decrement the per-task RCU nesting counter. + * After this, any interrupts or NMIs will increment and + * decrement the per-CPU counters. + */ + ORDERED_WRT_IRQ(me->rcu_read_lock_nesting) = nesting - 1; + + /* + * It is now safe to decrement this task's nesting count. + * NMIs that occur after this statement will route their + * rcu_read_lock() calls through this "else" clause, and + * will thus start incrementing the per-CPU coutner on + * their own. They will also clobber ->rcu_flipctr_idx, + * but that is OK, since we have already fetched it. + */ + + ORDERED_WRT_IRQ(__get_cpu_var(rcu_flipctr)[idx])--; + local_irq_restore(oldirq); + } +} + +/* + * If a global counter flip has occurred since the last time that we + * advanced callbacks, advance them. Hardware interrupts must be + * disabled when calling this function. + */ +static void __rcu_advance_callbacks(struct rcu_data *rdp) +{ + int cpu; + int i; + int wlc = 0; + + if (rdp->completed != rcu_ctrlblk.completed) { + if (rdp->waitlist[GP_STAGES - 1] != NULL) { + *rdp->donetail = rdp->waitlist[GP_STAGES - 1]; + rdp->donetail = rdp->waittail[GP_STAGES - 1]; + RCU_TRACE_RDP(rcupreempt_trace_move2done, rdp); + } + for (i = GP_STAGES - 2; i >= 0; i--) { + if (rdp->waitlist[i] != NULL) { + rdp->waitlist[i + 1] = rdp->waitlist[i]; + rdp->waittail[i + 1] = rdp->waittail[i]; + wlc++; + } else { + rdp->waitlist[i + 1] = NULL; + rdp->waittail[i + 1] = + &rdp->waitlist[i + 1]; + } + } + if (rdp->nextlist != NULL) { + rdp->waitlist[0] = rdp->nextlist; + rdp->waittail[0] = rdp->nexttail; + wlc++; + rdp->nextlist = NULL; + rdp->nexttail = &rdp->nextlist; + RCU_TRACE_RDP(rcupreempt_trace_move2wait, rdp); + } else { + rdp->waitlist[0] = NULL; + rdp->waittail[0] = &rdp->waitlist[0]; + } + rdp->waitlistcount = wlc; + rdp->completed = rcu_ctrlblk.completed; + } + + /* + * Check to see if this CPU needs to report that it has seen + * the most recent counter flip, thereby declaring that all + * subsequent rcu_read_lock() invocations will respect this flip. + */ + + cpu = raw_smp_processor_id(); + if (per_cpu(rcu_flip_flag, cpu) == rcu_flipped) { + smp_mb(); /* Subsequent counter accesses must see new value */ + per_cpu(rcu_flip_flag, cpu) = rcu_flip_seen; + smp_mb(); /* Subsequent RCU read-side critical sections */ + /* seen -after- acknowledgement. */ + } +} + +/* + * Get here when RCU is idle. Decide whether we need to + * move out of idle state, and return non-zero if so. + * "Straightforward" approach for the moment, might later + * use callback-list lengths, grace-period duration, or + * some such to determine when to exit idle state. + * Might also need a pre-idle test that does not acquire + * the lock, but let's get the simple case working first... + */ + +static int +rcu_try_flip_idle(void) +{ + int cpu; + + RCU_TRACE_ME(rcupreempt_trace_try_flip_i1); + if (!rcu_pending(smp_processor_id())) { + RCU_TRACE_ME(rcupreempt_trace_try_flip_ie1); + return 0; + } + + /* + * Do the flip. + */ + + RCU_TRACE_ME(rcupreempt_trace_try_flip_g1); + rcu_ctrlblk.completed++; /* stands in for rcu_try_flip_g2 */ + + /* + * Need a memory barrier so that other CPUs see the new + * counter value before they see the subsequent change of all + * the rcu_flip_flag instances to rcu_flipped. + */ + + smp_mb(); + + /* Now ask each CPU for acknowledgement of the flip. */ + + for_each_possible_cpu(cpu) + per_cpu(rcu_flip_flag, cpu) = rcu_flipped; + + return 1; +} + +/* + * Wait for CPUs to acknowledge the flip. + */ + +static int +rcu_try_flip_waitack(void) +{ + int cpu; + + RCU_TRACE_ME(rcupreempt_trace_try_flip_a1); + for_each_possible_cpu(cpu) + if (per_cpu(rcu_flip_flag, cpu) != rcu_flip_seen) { + RCU_TRACE_ME(rcupreempt_trace_try_flip_ae1); + return 0; + } + + /* + * Make sure our checks above don't bleed into subsequent + * waiting for the sum of the counters to reach zero. + */ + + smp_mb(); + RCU_TRACE_ME(rcupreempt_trace_try_flip_a2); + return 1; +} + +/* + * Wait for collective ``last'' counter to reach zero, + * then tell all CPUs to do an end-of-grace-period memory barrier. + */ + +static int +rcu_try_flip_waitzero(void) +{ + int cpu; + int lastidx = !(rcu_ctrlblk.completed & 0x1); + int sum = 0; + + /* Check to see if the sum of the "last" counters is zero. */ + + RCU_TRACE_ME(rcupreempt_trace_try_flip_z1); + for_each_possible_cpu(cpu) + sum += per_cpu(rcu_flipctr, cpu)[lastidx]; + if (sum != 0) { + RCU_TRACE_ME(rcupreempt_trace_try_flip_ze1); + return 0; + } + + /* Make sure we don't call for memory barriers before we see zero. */ + + smp_mb(); + + /* Call for a memory barrier from each CPU. */ + + for_each_possible_cpu(cpu) + per_cpu(rcu_mb_flag, cpu) = rcu_mb_needed; + + RCU_TRACE_ME(rcupreempt_trace_try_flip_z2); + return 1; +} + +/* + * Wait for all CPUs to do their end-of-grace-period memory barrier. + * Return 0 once all CPUs have done so. + */ + +static int +rcu_try_flip_waitmb(void) +{ + int cpu; + + RCU_TRACE_ME(rcupreempt_trace_try_flip_m1); + for_each_possible_cpu(cpu) + if (per_cpu(rcu_mb_flag, cpu) != rcu_mb_done) { + RCU_TRACE_ME(rcupreempt_trace_try_flip_me1); + return 0; + } + + smp_mb(); /* Ensure that the above checks precede any following flip. */ + RCU_TRACE_ME(rcupreempt_trace_try_flip_m2); + return 1; +} + +/* + * Attempt a single flip of the counters. Remember, a single flip does + * -not- constitute a grace period. Instead, the interval between + * at least three consecutive flips is a grace period. + * + * If anyone is nuts enough to run this CONFIG_PREEMPT_RCU implementation + * on a large SMP, they might want to use a hierarchical organization of + * the per-CPU-counter pairs. + */ +static void rcu_try_flip(void) +{ + unsigned long oldirq; + + RCU_TRACE_ME(rcupreempt_trace_try_flip_1); + if (unlikely(!spin_trylock_irqsave(&rcu_ctrlblk.fliplock, oldirq))) { + RCU_TRACE_ME(rcupreempt_trace_try_flip_e1); + return; + } + + /* + * Take the next transition(s) through the RCU grace-period + * flip-counter state machine. + */ + + switch (rcu_try_flip_state) { + case rcu_try_flip_idle_state: + if (rcu_try_flip_idle()) + rcu_try_flip_state = rcu_try_flip_waitack_state; + break; + case rcu_try_flip_waitack_state: + if (rcu_try_flip_waitack()) + rcu_try_flip_state = rcu_try_flip_waitzero_state; + break; + case rcu_try_flip_waitzero_state: + if (rcu_try_flip_waitzero()) + rcu_try_flip_state = rcu_try_flip_waitmb_state; + break; + case rcu_try_flip_waitmb_state: + if (rcu_try_flip_waitmb()) + rcu_try_flip_state = rcu_try_flip_idle_state; + } + spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, oldirq); +} + +/* + * Check to see if this CPU needs to do a memory barrier in order to + * ensure that any prior RCU read-side critical sections have committed + * their counter manipulations and critical-section memory references + * before declaring the grace period to be completed. + */ +static void rcu_check_mb(int cpu) +{ + if (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed) { + smp_mb(); /* Ensure RCU read-side accesses are visible. */ + per_cpu(rcu_mb_flag, cpu) = rcu_mb_done; + } +} + +void rcu_check_callbacks(int cpu, int user) +{ + unsigned long oldirq; + struct rcu_data *rdp = RCU_DATA_CPU(cpu); + + rcu_check_mb(cpu); + if (rcu_ctrlblk.completed == rdp->completed) { + rcu_try_flip(); + } + spin_lock_irqsave(&rdp->lock, oldirq); + RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp); + __rcu_advance_callbacks(rdp); + if (rdp->donelist == NULL) { + spin_unlock_irqrestore(&rdp->lock, oldirq); + } else { + spin_unlock_irqrestore(&rdp->lock, oldirq); + raise_softirq(RCU_SOFTIRQ); + } +} + +/* + * Needed by dynticks, to make sure all RCU processing has finished + * when we go idle: + */ +void rcu_advance_callbacks(int cpu, int user) +{ + unsigned long oldirq; + struct rcu_data *rdp = RCU_DATA_CPU(cpu); + + if (rcu_ctrlblk.completed == rdp->completed) { + rcu_try_flip(); + if (rcu_ctrlblk.completed == rdp->completed) { + return; + } + } + spin_lock_irqsave(&rdp->lock, oldirq); + RCU_TRACE_RDP(rcupreempt_trace_check_callbacks, rdp); + __rcu_advance_callbacks(rdp); + spin_unlock_irqrestore(&rdp->lock, oldirq); +} + +static void rcu_process_callbacks(struct softirq_action *unused) +{ + unsigned long flags; + struct rcu_head *next, *list; + struct rcu_data *rdp = RCU_DATA_ME(); + + spin_lock_irqsave(&rdp->lock, flags); + list = rdp->donelist; + if (list == NULL) { + spin_unlock_irqrestore(&rdp->lock, flags); + return; + } + rdp->donelist = NULL; + rdp->donetail = &rdp->donelist; + RCU_TRACE_RDP(rcupreempt_trace_done_remove, rdp); + spin_unlock_irqrestore(&rdp->lock, flags); + while (list) { + next = list->next; + list->func(list); + list = next; + RCU_TRACE_ME(rcupreempt_trace_invoke); + } +} + +void fastcall call_rcu(struct rcu_head *head, + void (*func)(struct rcu_head *rcu)) +{ + unsigned long oldirq; + struct rcu_data *rdp; + + head->func = func; + head->next = NULL; + local_irq_save(oldirq); + rdp = RCU_DATA_ME(); + spin_lock(&rdp->lock); + __rcu_advance_callbacks(rdp); + *rdp->nexttail = head; + rdp->nexttail = &head->next; + RCU_TRACE_RDP(rcupreempt_trace_next_add, rdp); + spin_unlock(&rdp->lock); + local_irq_restore(oldirq); +} + +/* + * Wait until all currently running preempt_disable() code segments + * (including hardware-irq-disable segments) complete. Note that + * in -rt this does -not- necessarily result in all currently executing + * interrupt -handlers- having completed. + */ +void __synchronize_sched(void) +{ + cpumask_t oldmask; + int cpu; + + if (sched_getaffinity(0, &oldmask) < 0) { + oldmask = cpu_possible_map; + } + for_each_online_cpu(cpu) { + sched_setaffinity(0, cpumask_of_cpu(cpu)); + schedule(); + } + sched_setaffinity(0, oldmask); +} + +/* + * Check to see if any future RCU-related work will need to be done + * by the current CPU, even if none need be done immediately, returning + * 1 if so. Assumes that notifiers would take care of handling any + * outstanding requests from the RCU core. + * + * This function is part of the RCU implementation; it is -not- + * an exported member of the RCU API. + */ +int rcu_needs_cpu(int cpu) +{ + struct rcu_data *rdp = RCU_DATA_CPU(cpu); + + return (rdp->donelist != NULL || + !!rdp->waitlistcount || + rdp->nextlist != NULL); +} + +int rcu_pending(int cpu) +{ + struct rcu_data *rdp = RCU_DATA_CPU(cpu); + + /* The CPU has at least one callback queued somewhere. */ + + if (rdp->donelist != NULL || + !!rdp->waitlistcount || + rdp->nextlist != NULL) + return 1; + + /* The RCU core needs an acknowledgement from this CPU. */ + + if ((per_cpu(rcu_flip_flag, cpu) == rcu_flipped) || + (per_cpu(rcu_mb_flag, cpu) == rcu_mb_needed)) + return 1; + + /* This CPU has fallen behind the global grace-period number. */ + + if (rdp->completed != rcu_ctrlblk.completed) + return 1; + + /* Nothing needed from this CPU. */ + + return 0; +} + +void __init __rcu_init(void) +{ + int cpu; + int i; + struct rcu_data *rdp; + +/*&&&&*/printk("WARNING: experimental non-atomic RCU implementation.\n"); + for_each_possible_cpu(cpu) { + rdp = RCU_DATA_CPU(cpu); + spin_lock_init(&rdp->lock); + rdp->completed = 0; + rdp->waitlistcount = 0; + rdp->nextlist = NULL; + rdp->nexttail = &rdp->nextlist; + for (i = 0; i < GP_STAGES; i++) { + rdp->waitlist[i] = NULL; + rdp->waittail[i] = &rdp->waitlist[i]; + } + rdp->donelist = NULL; + rdp->donetail = &rdp->donelist; + } + open_softirq(RCU_SOFTIRQ, rcu_process_callbacks, NULL); +/*&&&&*/printk("experimental non-atomic RCU implementation: init done\n"); +} + +/* + * Deprecated, use synchronize_rcu() or synchronize_sched() instead. + */ +void synchronize_kernel(void) +{ + synchronize_rcu(); +} + +#ifdef CONFIG_RCU_TRACE +int *rcupreempt_flipctr(int cpu) +{ + return &per_cpu(rcu_flipctr, cpu)[0]; +} +int rcupreempt_flip_flag(int cpu) +{ + return per_cpu(rcu_flip_flag, cpu); +} +int rcupreempt_mb_flag(int cpu) +{ + return per_cpu(rcu_mb_flag, cpu); +} +char *rcupreempt_try_flip_state_name(void) +{ + return rcu_try_flip_state_names[rcu_try_flip_state]; +} +struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu) +{ + struct rcu_data *rdp = RCU_DATA_CPU(cpu); + + return &rdp->trace; +} +EXPORT_SYMBOL_GPL(rcupreempt_flipctr); +EXPORT_SYMBOL_GPL(rcupreempt_flip_flag); +EXPORT_SYMBOL_GPL(rcupreempt_mb_flag); +EXPORT_SYMBOL_GPL(rcupreempt_try_flip_state_name); +#endif /* #ifdef RCU_TRACE */ + +EXPORT_SYMBOL_GPL(call_rcu); +EXPORT_SYMBOL_GPL(rcu_batches_completed); +EXPORT_SYMBOL_GPL(rcu_batches_completed_bh); +EXPORT_SYMBOL_GPL(__synchronize_sched); +EXPORT_SYMBOL_GPL(__rcu_read_lock); +EXPORT_SYMBOL_GPL(__rcu_read_unlock); diff -urpNa -X dontdiff linux-2.6.22-b-fixbarriers/kernel/rcupreempt_trace.c linux-2.6.22-c-preemptrcu/kernel/rcupreempt_trace.c --- linux-2.6.22-b-fixbarriers/kernel/rcupreempt_trace.c 1969-12-31 16:00:00.000000000 -0800 +++ linux-2.6.22-c-preemptrcu/kernel/rcupreempt_trace.c 2007-07-21 12:26:30.000000000 -0700 @@ -0,0 +1,330 @@ +/* + * Read-Copy Update tracing for realtime implementation + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright IBM Corporation, 2006 + * + * Papers: http://www.rdrop.com/users/paulmck/RCU + * + * For detailed explanation of Read-Copy Update mechanism see - + * Documentation/RCU/ *.txt + * + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static struct mutex rcupreempt_trace_mutex; +static char *rcupreempt_trace_buf; +#define RCUPREEMPT_TRACE_BUF_SIZE 4096 + +void rcupreempt_trace_move2done(struct rcupreempt_trace *trace) +{ + trace->done_length += trace->wait_length; + trace->done_add += trace->wait_length; + trace->wait_length = 0; +} +void rcupreempt_trace_move2wait(struct rcupreempt_trace *trace) +{ + trace->wait_length += trace->next_length; + trace->wait_add += trace->next_length; + trace->next_length = 0; +} +void rcupreempt_trace_try_flip_1(struct rcupreempt_trace *trace) +{ + atomic_inc(&trace->rcu_try_flip_1); +} +void rcupreempt_trace_try_flip_e1(struct rcupreempt_trace *trace) +{ + atomic_inc(&trace->rcu_try_flip_e1); +} +void rcupreempt_trace_try_flip_i1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_i1++; +} +void rcupreempt_trace_try_flip_ie1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_ie1++; +} +void rcupreempt_trace_try_flip_g1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_g1++; +} +void rcupreempt_trace_try_flip_a1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_a1++; +} +void rcupreempt_trace_try_flip_ae1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_ae1++; +} +void rcupreempt_trace_try_flip_a2(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_a2++; +} +void rcupreempt_trace_try_flip_z1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_z1++; +} +void rcupreempt_trace_try_flip_ze1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_ze1++; +} +void rcupreempt_trace_try_flip_z2(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_z2++; +} +void rcupreempt_trace_try_flip_m1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_m1++; +} +void rcupreempt_trace_try_flip_me1(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_me1++; +} +void rcupreempt_trace_try_flip_m2(struct rcupreempt_trace *trace) +{ + trace->rcu_try_flip_m2++; +} +void rcupreempt_trace_check_callbacks(struct rcupreempt_trace *trace) +{ + trace->rcu_check_callbacks++; +} +void rcupreempt_trace_done_remove(struct rcupreempt_trace *trace) +{ + trace->done_remove += trace->done_length; + trace->done_length = 0; +} +void rcupreempt_trace_invoke(struct rcupreempt_trace *trace) +{ + atomic_inc(&trace->done_invoked); +} +void rcupreempt_trace_next_add(struct rcupreempt_trace *trace) +{ + trace->next_add++; + trace->next_length++; +} + +static void rcupreempt_trace_sum(struct rcupreempt_trace *sp) +{ + struct rcupreempt_trace *cp; + int cpu; + + memset(sp, 0, sizeof(*sp)); + for_each_possible_cpu(cpu) { + cp = rcupreempt_trace_cpu(cpu); + sp->next_length += cp->next_length; + sp->next_add += cp->next_add; + sp->wait_length += cp->wait_length; + sp->wait_add += cp->wait_add; + sp->done_length += cp->done_length; + sp->done_add += cp->done_add; + sp->done_remove += cp->done_remove; + atomic_set(&sp->done_invoked, atomic_read(&cp->done_invoked)); + sp->rcu_check_callbacks += cp->rcu_check_callbacks; + atomic_set(&sp->rcu_try_flip_1, + atomic_read(&cp->rcu_try_flip_1)); + atomic_set(&sp->rcu_try_flip_e1, + atomic_read(&cp->rcu_try_flip_e1)); + sp->rcu_try_flip_i1 += cp->rcu_try_flip_i1; + sp->rcu_try_flip_ie1 += cp->rcu_try_flip_ie1; + sp->rcu_try_flip_g1 += cp->rcu_try_flip_g1; + sp->rcu_try_flip_a1 += cp->rcu_try_flip_a1; + sp->rcu_try_flip_ae1 += cp->rcu_try_flip_ae1; + sp->rcu_try_flip_a2 += cp->rcu_try_flip_a2; + sp->rcu_try_flip_z1 += cp->rcu_try_flip_z1; + sp->rcu_try_flip_ze1 += cp->rcu_try_flip_ze1; + sp->rcu_try_flip_z2 += cp->rcu_try_flip_z2; + sp->rcu_try_flip_m1 += cp->rcu_try_flip_m1; + sp->rcu_try_flip_me1 += cp->rcu_try_flip_me1; + sp->rcu_try_flip_m2 += cp->rcu_try_flip_m2; + } +} + +static ssize_t rcustats_read(struct file *filp, char __user *buffer, + size_t count, loff_t *ppos) +{ + struct rcupreempt_trace trace; + ssize_t bcount; + int cnt = 0; + + rcupreempt_trace_sum(&trace); + mutex_lock(&rcupreempt_trace_mutex); + snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt, + "ggp=%ld rcc=%ld\n", + rcu_batches_completed(), + trace.rcu_check_callbacks); + snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt, + "na=%ld nl=%ld wa=%ld wl=%ld da=%ld dl=%ld dr=%ld di=%d\n" + "1=%d e1=%d i1=%ld ie1=%ld g1=%ld a1=%ld ae1=%ld a2=%ld\n" + "z1=%ld ze1=%ld z2=%ld m1=%ld me1=%ld m2=%ld\n", + + trace.next_add, trace.next_length, + trace.wait_add, trace.wait_length, + trace.done_add, trace.done_length, + trace.done_remove, atomic_read(&trace.done_invoked), + atomic_read(&trace.rcu_try_flip_1), + atomic_read(&trace.rcu_try_flip_e1), + trace.rcu_try_flip_i1, trace.rcu_try_flip_ie1, + trace.rcu_try_flip_g1, + trace.rcu_try_flip_a1, trace.rcu_try_flip_ae1, + trace.rcu_try_flip_a2, + trace.rcu_try_flip_z1, trace.rcu_try_flip_ze1, + trace.rcu_try_flip_z2, + trace.rcu_try_flip_m1, trace.rcu_try_flip_me1, + trace.rcu_try_flip_m2); + bcount = simple_read_from_buffer(buffer, count, ppos, + rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); + mutex_unlock(&rcupreempt_trace_mutex); + return bcount; +} + +static ssize_t rcugp_read(struct file *filp, char __user *buffer, + size_t count, loff_t *ppos) +{ + long oldgp = rcu_batches_completed(); + ssize_t bcount; + + mutex_lock(&rcupreempt_trace_mutex); + synchronize_rcu(); + snprintf(rcupreempt_trace_buf, RCUPREEMPT_TRACE_BUF_SIZE, + "oldggp=%ld newggp=%ld\n", oldgp, rcu_batches_completed()); + bcount = simple_read_from_buffer(buffer, count, ppos, + rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); + mutex_unlock(&rcupreempt_trace_mutex); + return bcount; +} + +static ssize_t rcuctrs_read(struct file *filp, char __user *buffer, + size_t count, loff_t *ppos) +{ + int cnt = 0; + int cpu; + int f = rcu_batches_completed() & 0x1; + ssize_t bcount; + + mutex_lock(&rcupreempt_trace_mutex); + + cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE, + "CPU last cur F M\n"); + for_each_online_cpu(cpu) { + int *flipctr = rcupreempt_flipctr(cpu); + cnt += snprintf(&rcupreempt_trace_buf[cnt], + RCUPREEMPT_TRACE_BUF_SIZE - cnt, + "%3d %4d %3d %d %d\n", + cpu, + flipctr[!f], + flipctr[f], + rcupreempt_flip_flag(cpu), + rcupreempt_mb_flag(cpu)); + } + cnt += snprintf(&rcupreempt_trace_buf[cnt], + RCUPREEMPT_TRACE_BUF_SIZE - cnt, + "ggp = %ld, state = %s\n", + rcu_batches_completed(), + rcupreempt_try_flip_state_name()); + cnt += snprintf(&rcupreempt_trace_buf[cnt], + RCUPREEMPT_TRACE_BUF_SIZE - cnt, + "\n"); + bcount = simple_read_from_buffer(buffer, count, ppos, + rcupreempt_trace_buf, strlen(rcupreempt_trace_buf)); + mutex_unlock(&rcupreempt_trace_mutex); + return bcount; +} + +static struct file_operations rcustats_fops = { + .owner = THIS_MODULE, + .read = rcustats_read, +}; + +static struct file_operations rcugp_fops = { + .owner = THIS_MODULE, + .read = rcugp_read, +}; + +static struct file_operations rcuctrs_fops = { + .owner = THIS_MODULE, + .read = rcuctrs_read, +}; + +static struct dentry *rcudir, *statdir, *ctrsdir, *gpdir; +static int rcupreempt_debugfs_init(void) +{ + rcudir = debugfs_create_dir("rcu", NULL); + if (!rcudir) + goto out; + statdir = debugfs_create_file("rcustats", 0444, rcudir, + NULL, &rcustats_fops); + if (!statdir) + goto free_out; + + gpdir = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops); + if (!gpdir) + goto free_out; + + ctrsdir = debugfs_create_file("rcuctrs", 0444, rcudir, + NULL, &rcuctrs_fops); + if (!ctrsdir) + goto free_out; + return 0; +free_out: + if (statdir) + debugfs_remove(statdir); + if (gpdir) + debugfs_remove(gpdir); + debugfs_remove(rcudir); +out: + return 1; +} + +static int __init rcupreempt_trace_init(void) +{ + mutex_init(&rcupreempt_trace_mutex); + rcupreempt_trace_buf = kmalloc(RCUPREEMPT_TRACE_BUF_SIZE, GFP_KERNEL); + if (!rcupreempt_trace_buf) + return 1; + return rcupreempt_debugfs_init(); +} + +static void __exit rcupreempt_trace_cleanup(void) +{ + debugfs_remove(statdir); + debugfs_remove(gpdir); + debugfs_remove(ctrsdir); + debugfs_remove(rcudir); + kfree(rcupreempt_trace_buf); +} + + +module_init(rcupreempt_trace_init); +module_exit(rcupreempt_trace_cleanup); - 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/