rcutree_trace.c

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/*
 * Read-Copy Update tracing for classic 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, 2008
 *
 * Papers:  http://www.rdrop.com/users/paulmck/RCU
 *
 * For detailed explanation of Read-Copy Update mechanism see -
 *      Documentation/RCU
 *
 */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/mutex.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>

#define RCU_TREE_NONCORE
#include "rcutree.h"

static int show_rcubarrier(struct seq_file *m, void *unused)
{
    struct rcu_state *rsp;

    for_each_rcu_flavor(rsp)
        seq_printf(m, "%s: bcc: %d nbd: %lu\n",
               rsp->name,
               atomic_read(&rsp->barrier_cpu_count),
               rsp->n_barrier_done);
    return 0;
}

static int rcubarrier_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcubarrier, NULL);
}

static const struct file_operations rcubarrier_fops = {
    .owner = THIS_MODULE,
    .open = rcubarrier_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

#ifdef CONFIG_RCU_BOOST

static char convert_kthread_status(unsigned int kthread_status)
{
    if (kthread_status > RCU_KTHREAD_MAX)
        return '?';
    return "SRWOY"[kthread_status];
}

#endif /* #ifdef CONFIG_RCU_BOOST */

static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
{
    if (!rdp->beenonline)
        return;
    seq_printf(m, "%3d%cc=%lu g=%lu pq=%d qp=%d",
           rdp->cpu,
           cpu_is_offline(rdp->cpu) ? '!' : ' ',
           rdp->completed, rdp->gpnum,
           rdp->passed_quiesce, rdp->qs_pending);
    seq_printf(m, " dt=%d/%llx/%d df=%lu",
           atomic_read(&rdp->dynticks->dynticks),
           rdp->dynticks->dynticks_nesting,
           rdp->dynticks->dynticks_nmi_nesting,
           rdp->dynticks_fqs);
    seq_printf(m, " of=%lu", rdp->offline_fqs);
    seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
           rdp->qlen_lazy, rdp->qlen,
           ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
            rdp->nxttail[RCU_NEXT_TAIL]],
           ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
            rdp->nxttail[RCU_NEXT_READY_TAIL]],
           ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
            rdp->nxttail[RCU_WAIT_TAIL]],
           ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
#ifdef CONFIG_RCU_BOOST
    seq_printf(m, " kt=%d/%c ktl=%x",
           per_cpu(rcu_cpu_has_work, rdp->cpu),
           convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
                      rdp->cpu)),
           per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
#endif /* #ifdef CONFIG_RCU_BOOST */
    seq_printf(m, " b=%ld", rdp->blimit);
    seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
           rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
}

static int show_rcudata(struct seq_file *m, void *unused)
{
    int cpu;
    struct rcu_state *rsp;

    for_each_rcu_flavor(rsp) {
        seq_printf(m, "%s:\n", rsp->name);
        for_each_possible_cpu(cpu)
            print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu));
    }
    return 0;
}

static int rcudata_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcudata, NULL);
}

static const struct file_operations rcudata_fops = {
    .owner = THIS_MODULE,
    .open = rcudata_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
{
    if (!rdp->beenonline)
        return;
    seq_printf(m, "%d,%s,%lu,%lu,%d,%d",
           rdp->cpu,
           cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
           rdp->completed, rdp->gpnum,
           rdp->passed_quiesce, rdp->qs_pending);
    seq_printf(m, ",%d,%llx,%d,%lu",
           atomic_read(&rdp->dynticks->dynticks),
           rdp->dynticks->dynticks_nesting,
           rdp->dynticks->dynticks_nmi_nesting,
           rdp->dynticks_fqs);
    seq_printf(m, ",%lu", rdp->offline_fqs);
    seq_printf(m, ",%ld,%ld,\"%c%c%c%c\"", rdp->qlen_lazy, rdp->qlen,
           ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
            rdp->nxttail[RCU_NEXT_TAIL]],
           ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
            rdp->nxttail[RCU_NEXT_READY_TAIL]],
           ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
            rdp->nxttail[RCU_WAIT_TAIL]],
           ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
#ifdef CONFIG_RCU_BOOST
    seq_printf(m, ",%d,\"%c\"",
           per_cpu(rcu_cpu_has_work, rdp->cpu),
           convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
                      rdp->cpu)));
#endif /* #ifdef CONFIG_RCU_BOOST */
    seq_printf(m, ",%ld", rdp->blimit);
    seq_printf(m, ",%lu,%lu,%lu\n",
           rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
}

static int show_rcudata_csv(struct seq_file *m, void *unused)
{
    int cpu;
    struct rcu_state *rsp;

    seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pq\",");
    seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
    seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
#ifdef CONFIG_RCU_BOOST
    seq_puts(m, "\"kt\",\"ktl\"");
#endif /* #ifdef CONFIG_RCU_BOOST */
    seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
    for_each_rcu_flavor(rsp) {
        seq_printf(m, "\"%s:\"\n", rsp->name);
        for_each_possible_cpu(cpu)
            print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu));
    }
    return 0;
}

static int rcudata_csv_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcudata_csv, NULL);
}

static const struct file_operations rcudata_csv_fops = {
    .owner = THIS_MODULE,
    .open = rcudata_csv_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

#ifdef CONFIG_RCU_BOOST

static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
{
    seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
           rnp->grplo, rnp->grphi,
           "T."[list_empty(&rnp->blkd_tasks)],
           "N."[!rnp->gp_tasks],
           "E."[!rnp->exp_tasks],
           "B."[!rnp->boost_tasks],
           convert_kthread_status(rnp->boost_kthread_status),
           rnp->n_tasks_boosted, rnp->n_exp_boosts,
           rnp->n_normal_boosts);
    seq_printf(m, "j=%04x bt=%04x\n",
           (int)(jiffies & 0xffff),
           (int)(rnp->boost_time & 0xffff));
    seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
           rnp->n_balk_blkd_tasks,
           rnp->n_balk_exp_gp_tasks,
           rnp->n_balk_boost_tasks,
           rnp->n_balk_notblocked,
           rnp->n_balk_notyet,
           rnp->n_balk_nos);
}

static int show_rcu_node_boost(struct seq_file *m, void *unused)
{
    struct rcu_node *rnp;

    rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
        print_one_rcu_node_boost(m, rnp);
    return 0;
}

static int rcu_node_boost_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcu_node_boost, NULL);
}

static const struct file_operations rcu_node_boost_fops = {
    .owner = THIS_MODULE,
    .open = rcu_node_boost_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

/*
 * Create the rcuboost debugfs entry.  Standard error return.
 */
static int rcu_boost_trace_create_file(struct dentry *rcudir)
{
    return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
                    &rcu_node_boost_fops);
}

#else /* #ifdef CONFIG_RCU_BOOST */

static int rcu_boost_trace_create_file(struct dentry *rcudir)
{
    return 0;  /* There cannot be an error if we didn't create it! */
}

#endif /* #else #ifdef CONFIG_RCU_BOOST */

static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
{
    unsigned long gpnum;
    int level = 0;
    struct rcu_node *rnp;

    gpnum = rsp->gpnum;
    seq_printf(m, "%s: c=%lu g=%lu s=%d jfq=%ld j=%x ",
           rsp->name, rsp->completed, gpnum, rsp->fqs_state,
           (long)(rsp->jiffies_force_qs - jiffies),
           (int)(jiffies & 0xffff));
    seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
           rsp->n_force_qs, rsp->n_force_qs_ngp,
           rsp->n_force_qs - rsp->n_force_qs_ngp,
           rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen);
    for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
        if (rnp->level != level) {
            seq_puts(m, "\n");
            level = rnp->level;
        }
        seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
               rnp->qsmask, rnp->qsmaskinit,
               ".G"[rnp->gp_tasks != NULL],
               ".E"[rnp->exp_tasks != NULL],
               ".T"[!list_empty(&rnp->blkd_tasks)],
               rnp->grplo, rnp->grphi, rnp->grpnum);
    }
    seq_puts(m, "\n");
}

static int show_rcuhier(struct seq_file *m, void *unused)
{
    struct rcu_state *rsp;

    for_each_rcu_flavor(rsp)
        print_one_rcu_state(m, rsp);
    return 0;
}

static int rcuhier_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcuhier, NULL);
}

static const struct file_operations rcuhier_fops = {
    .owner = THIS_MODULE,
    .open = rcuhier_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
{
    unsigned long flags;
    unsigned long completed;
    unsigned long gpnum;
    unsigned long gpage;
    unsigned long gpmax;
    struct rcu_node *rnp = &rsp->node[0];

    raw_spin_lock_irqsave(&rnp->lock, flags);
    completed = rsp->completed;
    gpnum = rsp->gpnum;
    if (rsp->completed == rsp->gpnum)
        gpage = 0;
    else
        gpage = jiffies - rsp->gp_start;
    gpmax = rsp->gp_max;
    raw_spin_unlock_irqrestore(&rnp->lock, flags);
    seq_printf(m, "%s: completed=%ld  gpnum=%lu  age=%ld  max=%ld\n",
           rsp->name, completed, gpnum, gpage, gpmax);
}

static int show_rcugp(struct seq_file *m, void *unused)
{
    struct rcu_state *rsp;

    for_each_rcu_flavor(rsp)
        show_one_rcugp(m, rsp);
    return 0;
}

static int rcugp_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcugp, NULL);
}

static const struct file_operations rcugp_fops = {
    .owner = THIS_MODULE,
    .open = rcugp_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
{
    seq_printf(m, "%3d%cnp=%ld ",
           rdp->cpu,
           cpu_is_offline(rdp->cpu) ? '!' : ' ',
           rdp->n_rcu_pending);
    seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
           rdp->n_rp_qs_pending,
           rdp->n_rp_report_qs,
           rdp->n_rp_cb_ready,
           rdp->n_rp_cpu_needs_gp);
    seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
           rdp->n_rp_gp_completed,
           rdp->n_rp_gp_started,
           rdp->n_rp_need_nothing);
}

static int show_rcu_pending(struct seq_file *m, void *unused)
{
    int cpu;
    struct rcu_data *rdp;
    struct rcu_state *rsp;

    for_each_rcu_flavor(rsp) {
        seq_printf(m, "%s:\n", rsp->name);
        for_each_possible_cpu(cpu) {
            rdp = per_cpu_ptr(rsp->rda, cpu);
            if (rdp->beenonline)
                print_one_rcu_pending(m, rdp);
        }
    }
    return 0;
}

static int rcu_pending_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcu_pending, NULL);
}

static const struct file_operations rcu_pending_fops = {
    .owner = THIS_MODULE,
    .open = rcu_pending_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static int show_rcutorture(struct seq_file *m, void *unused)
{
    seq_printf(m, "rcutorture test sequence: %lu %s\n",
           rcutorture_testseq >> 1,
           (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
    seq_printf(m, "rcutorture update version number: %lu\n",
           rcutorture_vernum);
    return 0;
}

static int rcutorture_open(struct inode *inode, struct file *file)
{
    return single_open(file, show_rcutorture, NULL);
}

static const struct file_operations rcutorture_fops = {
    .owner = THIS_MODULE,
    .open = rcutorture_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = single_release,
};

static struct dentry *rcudir;

static int __init rcutree_trace_init(void)
{
    struct dentry *retval;

    rcudir = debugfs_create_dir("rcu", NULL);
    if (!rcudir)
        goto free_out;

    retval = debugfs_create_file("rcubarrier", 0444, rcudir,
                        NULL, &rcubarrier_fops);
    if (!retval)
        goto free_out;

    retval = debugfs_create_file("rcudata", 0444, rcudir,
                        NULL, &rcudata_fops);
    if (!retval)
        goto free_out;

    retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
                        NULL, &rcudata_csv_fops);
    if (!retval)
        goto free_out;

    if (rcu_boost_trace_create_file(rcudir))
        goto free_out;

    retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
    if (!retval)
        goto free_out;

    retval = debugfs_create_file("rcuhier", 0444, rcudir,
                        NULL, &rcuhier_fops);
    if (!retval)
        goto free_out;

    retval = debugfs_create_file("rcu_pending", 0444, rcudir,
                        NULL, &rcu_pending_fops);
    if (!retval)
        goto free_out;

    retval = debugfs_create_file("rcutorture", 0444, rcudir,
                        NULL, &rcutorture_fops);
    if (!retval)
        goto free_out;
    return 0;
free_out:
    debugfs_remove_recursive(rcudir);
    return 1;
}

static void __exit rcutree_trace_cleanup(void)
{
    debugfs_remove_recursive(rcudir);
}


module_init(rcutree_trace_init);
module_exit(rcutree_trace_cleanup);

MODULE_AUTHOR("Paul E. McKenney");
MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
MODULE_LICENSE("GPL");