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Date: Sun, 26 Oct 2008 14:59:30 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Lai Jiangshan <laijs@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, rjw@...k.pl,
dipankar@...ibm.com, tglx@...uxtronix.de, andi@...stfloor.org
Subject: Re: [PATCH] v3 rudimentary tracing for Classic RCU
On Thu, Oct 23, 2008 at 07:12:09PM +0800, Lai Jiangshan wrote:
>
> trivial ported it to seq_file.
> seq_file are very good for the output buffer.
Thank you for putting this together!!! Looks good at first glance --
I will test it out.
Thanx, Paul
> Signed-off-by: Lai Jiangshan <laijs@...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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