ftrace: improve seq_operation of ftrace
Impact: make ftrace position computing more sane
First remove useless ->pos field. Then we needn't check seq_printf
in .show like other place.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
Reviewed-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index cbf8b09..08b536a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -786,7 +786,6 @@
#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
struct ftrace_iterator {
- loff_t pos;
struct ftrace_page *pg;
unsigned idx;
unsigned flags;
@@ -811,6 +810,8 @@
iter->pg = iter->pg->next;
iter->idx = 0;
goto retry;
+ } else {
+ iter->idx = -1;
}
} else {
rec = &iter->pg->records[iter->idx++];
@@ -833,8 +834,6 @@
}
spin_unlock(&ftrace_lock);
- iter->pos = *pos;
-
return rec;
}
@@ -842,13 +841,15 @@
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
- loff_t l = -1;
- if (*pos > iter->pos)
- *pos = iter->pos;
+ if (*pos > 0) {
+ if (iter->idx < 0)
+ return p;
+ (*pos)--;
+ iter->idx--;
+ }
- l = *pos;
- p = t_next(m, p, &l);
+ p = t_next(m, p, pos);
return p;
}
@@ -859,21 +860,15 @@
static int t_show(struct seq_file *m, void *v)
{
- struct ftrace_iterator *iter = m->private;
struct dyn_ftrace *rec = v;
char str[KSYM_SYMBOL_LEN];
- int ret = 0;
if (!rec)
return 0;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
- ret = seq_printf(m, "%s\n", str);
- if (ret < 0) {
- iter->pos--;
- iter->idx--;
- }
+ seq_printf(m, "%s\n", str);
return 0;
}
@@ -899,7 +894,6 @@
return -ENOMEM;
iter->pg = ftrace_pages_start;
- iter->pos = 0;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
@@ -986,7 +980,6 @@
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
- iter->pos = 0;
iter->flags = enable ? FTRACE_ITER_FILTER :
FTRACE_ITER_NOTRACE;