/* * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition * Internal non-public definitions that provide either classic * or preemptible semantics. * * 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) 2010 Linaro * * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> */ #include <linux/kthread.h>#include <linux/module.h>#include <linux/debugfs.h>#include <linux/seq_file.h> /* Global control variables for rcupdate callback mechanism. */struct rcu_ctrlblk {	struct rcu_head *rcucblist;	/* List of pending callbacks (CBs). */	struct rcu_head **donetail;	/* ->next pointer of last "done" CB. */	struct rcu_head **curtail;	/* ->next pointer of last CB. */	RCU_TRACE(long qlen);		/* Number of pending CBs. */	RCU_TRACE(unsigned long gp_start); /* Start time for stalls. */	RCU_TRACE(unsigned long ticks_this_gp); /* Statistic for stalls. */	RCU_TRACE(unsigned long jiffies_stall); /* Jiffies at next stall. */	RCU_TRACE(const char *name);	/* Name of RCU type. */}; /* Definition for rcupdate control block. */static struct rcu_ctrlblk rcu_sched_ctrlblk = {	.donetail	= &rcu_sched_ctrlblk.rcucblist,	.curtail	= &rcu_sched_ctrlblk.rcucblist,	RCU_TRACE(.name = "rcu_sched")}; static struct rcu_ctrlblk rcu_bh_ctrlblk = {	.donetail	= &rcu_bh_ctrlblk.rcucblist,	.curtail	= &rcu_bh_ctrlblk.rcucblist,	RCU_TRACE(.name = "rcu_bh")}; #ifdef CONFIG_DEBUG_LOCK_ALLOC#include <linux/kernel_stat.h> int rcu_scheduler_active __read_mostly;EXPORT_SYMBOL_GPL(rcu_scheduler_active); /* * During boot, we forgive RCU lockdep issues.  After this function is * invoked, we start taking RCU lockdep issues seriously. */void __init rcu_scheduler_starting(void){	WARN_ON(nr_context_switches() > 0);	rcu_scheduler_active = 1;} #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ #ifdef CONFIG_RCU_TRACE static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n){	unsigned long flags; 	local_irq_save(flags);	rcp->qlen -= n;	local_irq_restore(flags);} /* * Dump statistics for TINY_RCU, such as they are. */static int show_tiny_stats(struct seq_file *m, void *unused){	seq_printf(m, "rcu_sched: qlen: %ld\n", rcu_sched_ctrlblk.qlen);	seq_printf(m, "rcu_bh: qlen: %ld\n", rcu_bh_ctrlblk.qlen);	return 0;} static int show_tiny_stats_open(struct inode *inode, struct file *file){	return single_open(file, show_tiny_stats, NULL);} static const struct file_operations show_tiny_stats_fops = {	.owner = THIS_MODULE,	.open = show_tiny_stats_open,	.read = seq_read,	.llseek = seq_lseek,	.release = single_release,}; static struct dentry *rcudir; static int __init rcutiny_trace_init(void){	struct dentry *retval; 	rcudir = debugfs_create_dir("rcu", NULL);	if (!rcudir)		goto free_out;	retval = debugfs_create_file("rcudata", 0444, rcudir,				     NULL, &show_tiny_stats_fops);	if (!retval)		goto free_out;	return 0;free_out:	debugfs_remove_recursive(rcudir);	return 1;} static void __exit rcutiny_trace_cleanup(void){	debugfs_remove_recursive(rcudir);} module_init(rcutiny_trace_init);module_exit(rcutiny_trace_cleanup); MODULE_AUTHOR("Paul E. McKenney");MODULE_DESCRIPTION("Read-Copy Update tracing for tiny implementation");MODULE_LICENSE("GPL"); static void check_cpu_stall(struct rcu_ctrlblk *rcp){	unsigned long j;	unsigned long js; 	if (rcu_cpu_stall_suppress)		return;	rcp->ticks_this_gp++;	j = jiffies;	js = rcp->jiffies_stall;	if (*rcp->curtail && ULONG_CMP_GE(j, js)) {		pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",		       rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,		       jiffies - rcp->gp_start, rcp->qlen);		dump_stack();	}	if (*rcp->curtail && ULONG_CMP_GE(j, js))		rcp->jiffies_stall = jiffies +			3 * rcu_jiffies_till_stall_check() + 3;	else if (ULONG_CMP_GE(j, js))		rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();} static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp){	rcp->ticks_this_gp = 0;	rcp->gp_start = jiffies;	rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();} static void check_cpu_stalls(void){	RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk));	RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk));} #endif /* #ifdef CONFIG_RCU_TRACE */