175 lines
4.8 KiB
C
175 lines
4.8 KiB
C
/*
|
|
* 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 */
|