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Subject[PATCH] rcu: convert rcupreempt trace to seq file
Impact: also fix a bug in show_rcustats()

Use seq file for simplification, and the global buffer and mutex can be
removed.

While doing this, I found rcustats will never show 'ggp' and 'rcc' fields
due to a bug in show_rcustats().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
kernel/rcupreempt_trace.c | 155 ++++++++++++++++++++-------------------------
1 files changed, 69 insertions(+), 86 deletions(-)
diff --git a/kernel/rcupreempt_trace.c b/kernel/rcupreempt_trace.c
index 7c2665c..a0c8297 100644
--- a/kernel/rcupreempt_trace.c
+++ b/kernel/rcupreempt_trace.c
@@ -39,13 +39,9 @@
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
-#include <linux/mutex.h>
#include <linux/rcupreempt_trace.h>
#include <linux/debugfs.h>
-
-static struct mutex rcupreempt_trace_mutex;
-static char *rcupreempt_trace_buf;
-#define RCUPREEMPT_TRACE_BUF_SIZE 4096
+#include <linux/seq_file.h>

void rcupreempt_trace_move2done(struct rcupreempt_trace *trace)
{
@@ -170,110 +166,107 @@ static void rcupreempt_trace_sum(struct rcupreempt_trace *sp)
}
}

-static ssize_t rcustats_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
+static ssize_t show_rcustats(struct seq_file *m, void *unused)
{
struct rcupreempt_trace trace;
- ssize_t bcount;
- int cnt = 0;

rcupreempt_trace_sum(&trace);
- mutex_lock(&rcupreempt_trace_mutex);
- snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "ggp=%ld rcc=%ld\n",
- rcu_batches_completed(),
- trace.rcu_check_callbacks);
- snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "na=%ld nl=%ld wa=%ld wl=%ld da=%ld dl=%ld dr=%ld di=%d\n"
- "1=%d e1=%d i1=%ld ie1=%ld g1=%ld a1=%ld ae1=%ld a2=%ld\n"
- "z1=%ld ze1=%ld z2=%ld m1=%ld me1=%ld m2=%ld\n",

- trace.next_add, trace.next_length,
- trace.wait_add, trace.wait_length,
- trace.done_add, trace.done_length,
- trace.done_remove, atomic_read(&trace.done_invoked),
- atomic_read(&trace.rcu_try_flip_1),
- atomic_read(&trace.rcu_try_flip_e1),
- trace.rcu_try_flip_i1, trace.rcu_try_flip_ie1,
- trace.rcu_try_flip_g1,
- trace.rcu_try_flip_a1, trace.rcu_try_flip_ae1,
+ seq_printf(m, "ggp=%ld rcc=%ld\n",
+ rcu_batches_completed(),
+ trace.rcu_check_callbacks);
+
+ seq_printf(m, "na=%ld nl=%ld wa=%ld wl=%ld da=%ld dl=%ld dr=%ld di=%d\n"
+ "1=%d e1=%d i1=%ld ie1=%ld g1=%ld a1=%ld ae1=%ld a2=%ld\n"
+ "z1=%ld ze1=%ld z2=%ld m1=%ld me1=%ld m2=%ld\n",
+ trace.next_add, trace.next_length,
+ trace.wait_add, trace.wait_length,
+ trace.done_add, trace.done_length,
+ trace.done_remove, atomic_read(&trace.done_invoked),
+ atomic_read(&trace.rcu_try_flip_1),
+ atomic_read(&trace.rcu_try_flip_e1),
+ trace.rcu_try_flip_i1, trace.rcu_try_flip_ie1,
+ trace.rcu_try_flip_g1,
+ trace.rcu_try_flip_a1, trace.rcu_try_flip_ae1,
trace.rcu_try_flip_a2,
- trace.rcu_try_flip_z1, trace.rcu_try_flip_ze1,
+ trace.rcu_try_flip_z1, trace.rcu_try_flip_ze1,
trace.rcu_try_flip_z2,
- trace.rcu_try_flip_m1, trace.rcu_try_flip_me1,
- trace.rcu_try_flip_m2);
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
+ trace.rcu_try_flip_m1, trace.rcu_try_flip_me1,
+ trace.rcu_try_flip_m2);
+
+ return 0;
+}
+
+static int rcustats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcustats, NULL);
}

-static ssize_t rcugp_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
+static ssize_t show_rcugp(struct seq_file *m, void *unused)
{
long oldgp = rcu_batches_completed();
- ssize_t bcount;

- mutex_lock(&rcupreempt_trace_mutex);
synchronize_rcu();
- snprintf(rcupreempt_trace_buf, RCUPREEMPT_TRACE_BUF_SIZE,
- "oldggp=%ld newggp=%ld\n", oldgp, rcu_batches_completed());
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
+ seq_printf(m, "oldggp=%ld newggp=%ld\n",
+ oldgp, rcu_batches_completed());
+
+ return 0;
}

-static ssize_t rcuctrs_read(struct file *filp, char __user *buffer,
- size_t count, loff_t *ppos)
+static int rcugp_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcugp, NULL);
+}
+
+static ssize_t show_rcuctrs(struct seq_file *m, void *unused)
{
- int cnt = 0;
int cpu;
int f = rcu_batches_completed() & 0x1;
- ssize_t bcount;
-
- mutex_lock(&rcupreempt_trace_mutex);

- cnt += snprintf(&rcupreempt_trace_buf[cnt], RCUPREEMPT_TRACE_BUF_SIZE,
- "CPU last cur F M\n");
+ seq_puts(m, "CPU last cur F M\n");
for_each_online_cpu(cpu) {
long *flipctr = rcupreempt_flipctr(cpu);
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "%3d %4ld %3ld %d %d\n",
- cpu,
- flipctr[!f],
- flipctr[f],
- rcupreempt_flip_flag(cpu),
- rcupreempt_mb_flag(cpu));
+ seq_printf(m, "%3d %4ld %3ld %d %d\n",
+ cpu,
+ flipctr[!f],
+ flipctr[f],
+ rcupreempt_flip_flag(cpu),
+ rcupreempt_mb_flag(cpu));
}
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "ggp = %ld, state = %s\n",
- rcu_batches_completed(),
- rcupreempt_try_flip_state_name());
- cnt += snprintf(&rcupreempt_trace_buf[cnt],
- RCUPREEMPT_TRACE_BUF_SIZE - cnt,
- "\n");
- bcount = simple_read_from_buffer(buffer, count, ppos,
- rcupreempt_trace_buf, strlen(rcupreempt_trace_buf));
- mutex_unlock(&rcupreempt_trace_mutex);
- return bcount;
+ seq_printf(m, "ggp = %ld, state = %s\n",
+ rcu_batches_completed(),
+ rcupreempt_try_flip_state_name());
+
+ return 0;
+}
+
+static int rcuctrs_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_rcuctrs, NULL);
}

static struct file_operations rcustats_fops = {
.owner = THIS_MODULE,
- .read = rcustats_read,
+ .open = rcustats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
};

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

static struct file_operations rcuctrs_fops = {
.owner = THIS_MODULE,
- .read = rcuctrs_read,
+ .open = rcuctrs_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
};

static struct dentry *rcudir, *statdir, *ctrsdir, *gpdir;
@@ -308,16 +301,7 @@ out:

static int __init rcupreempt_trace_init(void)
{
- int ret;
-
- mutex_init(&rcupreempt_trace_mutex);
- rcupreempt_trace_buf = kmalloc(RCUPREEMPT_TRACE_BUF_SIZE, GFP_KERNEL);
- if (!rcupreempt_trace_buf)
- return 1;
- ret = rcupreempt_debugfs_init();
- if (ret)
- kfree(rcupreempt_trace_buf);
- return ret;
+ return rcupreempt_debugfs_init();
}

static void __exit rcupreempt_trace_cleanup(void)
@@ -326,7 +310,6 @@ static void __exit rcupreempt_trace_cleanup(void)
debugfs_remove(gpdir);
debugfs_remove(ctrsdir);
debugfs_remove(rcudir);
- kfree(rcupreempt_trace_buf);
}


--
1.5.4.rc3


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