cregit-Linux how code gets into the kernel

Release 4.7 kernel/rcu/tiny_plugin.h

Directory: kernel/rcu
/*
 * 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, you can access it online at
 * http://www.gnu.org/licenses/gpl-2.0.html.
 *
 * Copyright (c) 2010 Linaro
 *
 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 */

#include <linux/kthread.h>
#include <linux/init.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; }

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#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); }

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/* * 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; }

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static int show_tiny_stats_open(struct inode *inode, struct file *file) { return single_open(file, show_tiny_stats, NULL); }

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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; }

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device_initcall(rcutiny_trace_init);
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 = READ_ONCE(rcp->jiffies_stall); if (rcp->rcucblist && 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, DYNTICK_TASK_EXIT_IDLE, jiffies - rcp->gp_start, rcp->qlen); dump_stack(); WRITE_ONCE(rcp->jiffies_stall, jiffies + 3 * rcu_jiffies_till_stall_check() + 3); } else if (ULONG_CMP_GE(j, js)) { WRITE_ONCE(rcp->jiffies_stall, jiffies + rcu_jiffies_till_stall_check()); } }

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miroslav benesmiroslav benes43.20%120.00%
himangi saraogihimangi saraogi43.20%120.00%
lai jiangshanlai jiangshan10.80%120.00%
Total125100.00%5100.00%


static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp) { rcp->ticks_this_gp = 0; rcp->gp_start = jiffies; WRITE_ONCE(rcp->jiffies_stall, jiffies + rcu_jiffies_till_stall_check()); }

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static void check_cpu_stalls(void) { RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk)); RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk)); }

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#endif /* #ifdef CONFIG_RCU_TRACE */

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paul gortmakerpaul gortmaker40.70%211.76%
miroslav benesmiroslav benes40.70%15.88%
steven rostedtsteven rostedt10.17%15.88%
lai jiangshanlai jiangshan10.17%15.88%
Total575100.00%17100.00%
Directory: kernel/rcu
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