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Subject[PATCH 08/13] tracing: Use seq file for trace_clock
The buffer for the output is as small as 64 bytes, so it'll
overflow if we add more clock type. Use seq file instead.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
kernel/trace/trace.c | 24 +++++++++++++++---------
1 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e989fc9..75871e5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3327,21 +3327,18 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
return cnt;
}

-static ssize_t tracing_clock_read(struct file *filp, char __user *ubuf,
- size_t cnt, loff_t *ppos)
+static int tracing_clock_show(struct seq_file *m, void *v)
{
- char buf[64];
- int bufiter = 0;
int i;

for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
- bufiter += snprintf(buf + bufiter, sizeof(buf) - bufiter,
+ seq_printf(m,
"%s%s%s%s", i ? " " : "",
i == trace_clock_id ? "[" : "", trace_clocks[i].name,
i == trace_clock_id ? "]" : "");
- bufiter += snprintf(buf + bufiter, sizeof(buf) - bufiter, "\n");
+ seq_putc(m, '\n');

- return simple_read_from_buffer(ubuf, cnt, ppos, buf, bufiter);
+ return 0;
}

static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
@@ -3383,6 +3380,13 @@ static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
return cnt;
}

+static int tracing_clock_open(struct inode *inode, struct file *file)
+{
+ if (tracing_disabled)
+ return -ENODEV;
+ return single_open(file, tracing_clock_show, NULL);
+}
+
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
@@ -3421,8 +3425,10 @@ static const struct file_operations tracing_mark_fops = {
};

static const struct file_operations trace_clock_fops = {
- .open = tracing_open_generic,
- .read = tracing_clock_read,
+ .open = tracing_clock_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
.write = tracing_clock_write,
};

--
1.6.3


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