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    SubjectRe: [PATCH] v3 rudimentary tracing for Classic RCU

    trivial ported it to seq_file.
    seq_file are very good for the output buffer.

    Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
    ---
    diff --git a/kernel/rcuclassic_trace.c b/kernel/rcuclassic_trace.c
    index d19780b..f19217c
    --- a/kernel/rcuclassic_trace.c
    +++ b/kernel/rcuclassic_trace.c
    @@ -23,157 +23,167 @@
    * 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 <asm/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>

    -static DEFINE_MUTEX(rcuclassic_trace_mutex);
    -static char *rcuclassic_trace_buf;
    -#define RCUCLASSIC_TRACE_BUF_SIZE (128 * num_possible_cpus() + 100)
    +static struct rcu_data *get_rcu_data_bh(int cpu)
    +{
    + return &per_cpu(rcu_bh_data, cpu);
    +}

    -static int print_one_rcu_data(struct rcu_data *rdp, char *buf, char *ebuf)
    +static struct rcu_data *get_rcu_data(int cpu)
    {
    - int cnt = 0;
    + return &per_cpu(rcu_data, cpu);
    +}

    +static int show_rcu_data(struct seq_file *m, void *v)
    +{
    + struct rcu_data *rdp = v;
    if (!rdp->beenonline)
    return 0;
    - cnt += snprintf(&buf[cnt], ebuf - &buf[cnt],
    - "%3d%cqb=%ld b=%ld pq=%d qsp=%d ql=%ld bl=%ld\n",
    - rdp->cpu, cpu_is_offline(rdp->cpu) ? '!' : ' ',
    - rdp->quiescbatch, rdp->batch, rdp->passed_quiesc,
    - rdp->qs_pending, rdp->qlen, rdp->blimit);
    - return cnt;
    +
    + seq_printf(m, "processor\t: %d", rdp->cpu);
    + if (cpu_is_offline(rdp->cpu))
    + seq_puts(m, "!\n");
    + else
    + seq_puts(m, "\n");
    + seq_printf(m, "quiescbatch\t: %ld\n", rdp->quiescbatch);
    + seq_printf(m, "batch\t: %ld\n", rdp->batch);
    + seq_printf(m, "passed_quiesc\t: %d\n", rdp->passed_quiesc);
    + seq_printf(m, "qs_pending\t: %d\n", rdp->qs_pending);
    + seq_printf(m, "qlen\t: %ld\n", rdp->qlen);
    + seq_printf(m, "blimit\t: %ld\n", rdp->blimit);
    + seq_puts(m, "\n\n");
    + return 0;
    }

    -#define PRINT_RCU_DATA(name, buf, ebuf) \
    - do { \
    - int _p_r_d_i; \
    - \
    - for_each_possible_cpu(_p_r_d_i) \
    - (buf) += print_one_rcu_data(&per_cpu(name, _p_r_d_i), \
    - buf, ebuf); \
    - } while (0)
    -
    -static ssize_t rcudata_read(struct file *filp, char __user *buffer,
    - size_t count, loff_t *ppos)
    +static void *c_start(struct seq_file *m, loff_t *pos)
    {
    - ssize_t bcount;
    - char *buf = rcuclassic_trace_buf;
    - char *ebuf = &rcuclassic_trace_buf[RCUCLASSIC_TRACE_BUF_SIZE];
    -
    - mutex_lock(&rcuclassic_trace_mutex);
    - buf += snprintf(buf, ebuf - buf, "rcu:\n");
    - PRINT_RCU_DATA(rcu_data, buf, ebuf);
    - buf += snprintf(buf, ebuf - buf, "rcu_bh:\n");
    - PRINT_RCU_DATA(rcu_bh_data, buf, ebuf);
    - bcount = simple_read_from_buffer(buffer, count, ppos,
    - rcuclassic_trace_buf, strlen(rcuclassic_trace_buf));
    - mutex_unlock(&rcuclassic_trace_mutex);
    - return bcount;
    + typedef struct rcu_data *(*get_data_func)(int);
    +
    + if (*pos == 0) /* just in case, cpu 0 is not the first */
    + *pos = first_cpu(cpu_possible_map);
    + else
    + *pos = next_cpu_nr(*pos - 1, cpu_possible_map);
    + if ((*pos) < nr_cpu_ids)
    + return ((get_data_func)m->private)(*pos);
    + return NULL;
    }

    -static int print_one_rcu_ctrlblk(struct rcu_ctrlblk *rcp, char *buf, char *ebuf)
    +static void *c_next(struct seq_file *m, void *v, loff_t *pos)
    {
    - int cnt = 0;
    -
    - cnt += snprintf(&buf[cnt], ebuf - &buf[cnt], "cur=%ld completed=%ld "
    - "pending=%ld s=%d\n\t",
    - rcp->cur, rcp->completed,
    - rcp->pending, rcp->signaled);
    - cnt += cpulist_scnprintf(&buf[cnt], ebuf - &buf[cnt], rcp->cpumask);
    - cnt += snprintf(&buf[cnt], ebuf - &buf[cnt], "\n");
    - return cnt;
    + (*pos)++;
    + return c_start(m, pos);
    }

    -static ssize_t rcucb_read(struct file *filp, char __user *buffer,
    - size_t count, loff_t *ppos)
    +static void c_stop(struct seq_file *m, void *v)
    {
    - ssize_t bcount;
    - char *buf = rcuclassic_trace_buf;
    - char *ebuf = &rcuclassic_trace_buf[RCUCLASSIC_TRACE_BUF_SIZE];
    -
    - mutex_lock(&rcuclassic_trace_mutex);
    - buf += snprintf(buf, ebuf - buf, "rcu: ");
    - buf += print_one_rcu_ctrlblk(&rcu_ctrlblk, buf, ebuf);
    - buf += snprintf(buf, ebuf - buf, "rcu_bh: ");
    - buf += print_one_rcu_ctrlblk(&rcu_bh_ctrlblk, buf, ebuf);
    - buf += snprintf(buf, ebuf - buf, "online: ");
    - buf += cpulist_scnprintf(buf, ebuf - buf, cpu_online_map);
    - buf += snprintf(buf, ebuf - buf, "\n");
    - bcount = simple_read_from_buffer(buffer, count, ppos,
    - rcuclassic_trace_buf, strlen(rcuclassic_trace_buf));
    - mutex_unlock(&rcuclassic_trace_mutex);
    - return bcount;
    }

    -static struct file_operations rcudata_fops = {
    - .owner = THIS_MODULE,
    - .read = rcudata_read,
    +const struct seq_operations rcu_data_seq_op = {
    + .start = c_start,
    + .next = c_next,
    + .stop = c_stop,
    + .show = show_rcu_data,
    };

    +static int rcu_data_open(struct inode *inode, struct file *file)
    +{
    + int ret = seq_open(file, &rcu_data_seq_op);
    + if (ret)
    + return ret;
    + ((struct seq_file *)file->private_data)->private = inode->i_private;
    + return 0;
    +}
    +
    +static const struct file_operations rcu_data_fops = {
    + .owner = THIS_MODULE,
    + .open = rcu_data_open,
    + .read = seq_read,
    + .llseek = seq_lseek,
    + .release = seq_release,
    +};
    +
    +static void print_one_rcu_ctrlblk(struct seq_file *m, struct rcu_ctrlblk *rcp)
    +{
    + seq_printf(m, "cur=%ld completed=%ld pending=%ld s=%d\n\t",
    + rcp->cur, rcp->completed, rcp->pending, rcp->signaled);
    + seq_cpumask(m, &rcp->cpumask);
    + seq_puts(m, "\n");
    +}
    +
    +static int show_rcucb(struct seq_file *m, void *unused)
    +{
    + seq_puts(m, "rcu: ");
    + print_one_rcu_ctrlblk(m, &rcu_ctrlblk);
    + seq_puts(m, "rcu_bh: ");
    + print_one_rcu_ctrlblk(m, &rcu_bh_ctrlblk);
    + seq_puts(m, "online: ");
    + seq_cpumask(m, &cpu_online_map);
    + seq_puts(m, "\n");
    + return 0;
    +}
    +
    +static int rcucb_open(struct inode *inode, struct file *file)
    +{
    + return single_open(file, show_rcucb, NULL);
    +}
    +
    static struct file_operations rcucb_fops = {
    - .owner = THIS_MODULE,
    - .read = rcucb_read,
    + .owner = THIS_MODULE,
    + .open = rcucb_open,
    + .read = seq_read,
    + .llseek = seq_lseek,
    + .release = single_release,
    };

    -static struct dentry *rcudir, *datadir, *cbdir;
    -static int rcuclassic_debugfs_init(void)
    +static struct dentry *rcudir, *rcu_bh_data_file, *rcu_data_file, *rcucb_file;
    +
    +static int __init rcuclassic_trace_init(void)
    {
    rcudir = debugfs_create_dir("rcu", NULL);
    if (!rcudir)
    goto out;
    - datadir = debugfs_create_file("rcudata", 0444, rcudir,
    - NULL, &rcudata_fops);
    - if (!datadir)
    - goto free_out;
    - cbdir = debugfs_create_file("rcucb", 0444, rcudir, NULL, &rcucb_fops);
    - if (!cbdir)
    - goto free_out;
    +
    + rcu_bh_data_file = debugfs_create_file("rcu_bh_data", 0444, rcudir,
    + get_rcu_data_bh, &rcu_data_fops);
    + if (!rcu_bh_data_file)
    + goto out_rcudir;
    +
    + rcu_data_file = debugfs_create_file("rcu_data", 0444, rcudir,
    + get_rcu_data, &rcu_data_fops);
    + if (!rcu_data_file)
    + goto out_rcudata_bh_file;
    +
    + rcucb_file = debugfs_create_file("rcucb", 0444, rcudir,
    + NULL, &rcucb_fops);
    + if (!rcucb_file)
    + goto out_rcudata_file;
    return 0;
    -free_out:
    - if (datadir)
    - debugfs_remove(datadir);
    +
    +out_rcudata_file:
    + debugfs_remove(rcu_data_file);
    +out_rcudata_bh_file:
    + debugfs_remove(rcu_bh_data_file);
    +out_rcudir:
    debugfs_remove(rcudir);
    out:
    return 1;
    }

    -static int __init rcuclassic_trace_init(void)
    -{
    - int ret;
    -
    - rcuclassic_trace_buf = kmalloc(RCUCLASSIC_TRACE_BUF_SIZE, GFP_KERNEL);
    - if (!rcuclassic_trace_buf)
    - return 1;
    - ret = rcuclassic_debugfs_init();
    - if (ret)
    - kfree(rcuclassic_trace_buf);
    - return ret;
    -}
    -
    static void __exit rcuclassic_trace_cleanup(void)
    {
    - debugfs_remove(datadir);
    - debugfs_remove(cbdir);
    + debugfs_remove(rcucb_file);
    + debugfs_remove(rcu_data_file);
    + debugfs_remove(rcu_bh_data_file);
    debugfs_remove(rcudir);
    - kfree(rcuclassic_trace_buf);
    }

    -
    module_init(rcuclassic_trace_init);
    module_exit(rcuclassic_trace_cleanup);
    +
    +MODULE_AUTHOR("Paul E. McKenney");
    +MODULE_DESCRIPTION("Read-Copy Update tracing for classic implementation");
    +MODULE_LICENSE("GPL");


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      Last update: 2008-10-23 13:17    [W:0.044 / U:149.148 seconds]
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