e66c33d579
All the RCU tracepoints and functions that reference char pointers do so with just 'char *' even though they do not modify the contents of the string itself. This will cause warnings if a const char * is used in one of these functions. The RCU tracepoints store the pointer to the string to refer back to them when the trace output is displayed. As this can be minutes, hours or even days later, those strings had better be constant. This change also opens the door to allow the RCU tracepoint strings and their addresses to be exported so that userspace tracing tools can translate the contents of the pointers of the RCU tracepoints. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
175 lines
4.8 KiB
C
175 lines
4.8 KiB
C
/*
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* Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition
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* Internal non-public definitions that provide either classic
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* or preemptible semantics.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (c) 2010 Linaro
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*
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* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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*/
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#include <linux/kthread.h>
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#include <linux/module.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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/* Global control variables for rcupdate callback mechanism. */
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struct rcu_ctrlblk {
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struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */
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struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
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struct rcu_head **curtail; /* ->next pointer of last CB. */
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RCU_TRACE(long qlen); /* Number of pending CBs. */
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RCU_TRACE(unsigned long gp_start); /* Start time for stalls. */
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RCU_TRACE(unsigned long ticks_this_gp); /* Statistic for stalls. */
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RCU_TRACE(unsigned long jiffies_stall); /* Jiffies at next stall. */
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RCU_TRACE(const char *name); /* Name of RCU type. */
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};
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/* Definition for rcupdate control block. */
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static struct rcu_ctrlblk rcu_sched_ctrlblk = {
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.donetail = &rcu_sched_ctrlblk.rcucblist,
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.curtail = &rcu_sched_ctrlblk.rcucblist,
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RCU_TRACE(.name = "rcu_sched")
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};
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static struct rcu_ctrlblk rcu_bh_ctrlblk = {
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.donetail = &rcu_bh_ctrlblk.rcucblist,
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.curtail = &rcu_bh_ctrlblk.rcucblist,
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RCU_TRACE(.name = "rcu_bh")
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};
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#include <linux/kernel_stat.h>
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int rcu_scheduler_active __read_mostly;
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EXPORT_SYMBOL_GPL(rcu_scheduler_active);
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/*
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* During boot, we forgive RCU lockdep issues. After this function is
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* invoked, we start taking RCU lockdep issues seriously.
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*/
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void __init rcu_scheduler_starting(void)
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{
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WARN_ON(nr_context_switches() > 0);
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rcu_scheduler_active = 1;
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}
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#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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#ifdef CONFIG_RCU_TRACE
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static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n)
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{
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unsigned long flags;
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local_irq_save(flags);
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rcp->qlen -= n;
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local_irq_restore(flags);
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}
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/*
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* Dump statistics for TINY_RCU, such as they are.
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*/
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static int show_tiny_stats(struct seq_file *m, void *unused)
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{
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seq_printf(m, "rcu_sched: qlen: %ld\n", rcu_sched_ctrlblk.qlen);
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seq_printf(m, "rcu_bh: qlen: %ld\n", rcu_bh_ctrlblk.qlen);
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return 0;
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}
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static int show_tiny_stats_open(struct inode *inode, struct file *file)
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{
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return single_open(file, show_tiny_stats, NULL);
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}
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static const struct file_operations show_tiny_stats_fops = {
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.owner = THIS_MODULE,
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.open = show_tiny_stats_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static struct dentry *rcudir;
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static int __init rcutiny_trace_init(void)
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{
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struct dentry *retval;
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rcudir = debugfs_create_dir("rcu", NULL);
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if (!rcudir)
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goto free_out;
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retval = debugfs_create_file("rcudata", 0444, rcudir,
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NULL, &show_tiny_stats_fops);
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if (!retval)
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goto free_out;
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return 0;
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free_out:
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debugfs_remove_recursive(rcudir);
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return 1;
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}
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static void __exit rcutiny_trace_cleanup(void)
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{
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debugfs_remove_recursive(rcudir);
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}
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module_init(rcutiny_trace_init);
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module_exit(rcutiny_trace_cleanup);
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MODULE_AUTHOR("Paul E. McKenney");
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MODULE_DESCRIPTION("Read-Copy Update tracing for tiny implementation");
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MODULE_LICENSE("GPL");
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static void check_cpu_stall(struct rcu_ctrlblk *rcp)
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{
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unsigned long j;
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unsigned long js;
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if (rcu_cpu_stall_suppress)
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return;
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rcp->ticks_this_gp++;
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j = jiffies;
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js = rcp->jiffies_stall;
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if (*rcp->curtail && ULONG_CMP_GE(j, js)) {
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pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
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rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,
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jiffies - rcp->gp_start, rcp->qlen);
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dump_stack();
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}
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if (*rcp->curtail && ULONG_CMP_GE(j, js))
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rcp->jiffies_stall = jiffies +
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3 * rcu_jiffies_till_stall_check() + 3;
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else if (ULONG_CMP_GE(j, js))
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rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
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}
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static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
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{
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rcp->ticks_this_gp = 0;
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rcp->gp_start = jiffies;
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rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
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}
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static void check_cpu_stalls(void)
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{
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RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk));
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RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk));
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}
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#endif /* #ifdef CONFIG_RCU_TRACE */
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