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Subject[PATCH 4/8] ftrace: Remove FTRACE_FL_FAILED flag
From: Steven Rostedt <srostedt@redhat.com>

Since we disable all function tracer processing if we detect
that a modification of a instruction had failed, we do not need
to track that the record has failed. No more ftrace processing
is allowed, and the FTRACE_FL_FAILED flag is pointless.

Removing this flag simplifies some of the code, but some ftrace_disabled
checks needed to be added or move around a little.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ftrace.h | 9 ++---
kernel/trace/ftrace.c | 76 +++++++++++++++++++++++++++++------------------
2 files changed, 51 insertions(+), 34 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ca29e03..2a195ff 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -147,11 +147,10 @@ extern int ftrace_text_reserved(void *start, void *end);

enum {
FTRACE_FL_FREE = (1 << 0),
- FTRACE_FL_FAILED = (1 << 1),
- FTRACE_FL_FILTER = (1 << 2),
- FTRACE_FL_ENABLED = (1 << 3),
- FTRACE_FL_NOTRACE = (1 << 4),
- FTRACE_FL_CONVERTED = (1 << 5),
+ FTRACE_FL_FILTER = (1 << 1),
+ FTRACE_FL_ENABLED = (1 << 2),
+ FTRACE_FL_NOTRACE = (1 << 3),
+ FTRACE_FL_CONVERTED = (1 << 4),
};

struct dyn_ftrace {
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 97b30f8..eb19fae 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1083,19 +1083,20 @@ static void ftrace_replace_code(int enable)
struct ftrace_page *pg;
int failed;

+ if (unlikely(ftrace_disabled))
+ return;
+
do_for_each_ftrace_rec(pg, rec) {
/*
* Skip over free records, records that have
* failed and not converted.
*/
if (rec->flags & FTRACE_FL_FREE ||
- rec->flags & FTRACE_FL_FAILED ||
!(rec->flags & FTRACE_FL_CONVERTED))
continue;

failed = __ftrace_replace_code(rec, enable);
if (failed) {
- rec->flags |= FTRACE_FL_FAILED;
ftrace_bug(failed, rec->ip);
/* Stop processing */
return;
@@ -1111,10 +1112,12 @@ ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)

ip = rec->ip;

+ if (unlikely(ftrace_disabled))
+ return 0;
+
ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
if (ret) {
ftrace_bug(ret, ip);
- rec->flags |= FTRACE_FL_FAILED;
return 0;
}
return 1;
@@ -1466,6 +1469,9 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
struct ftrace_iterator *iter = m->private;
struct dyn_ftrace *rec = NULL;

+ if (unlikely(ftrace_disabled))
+ return NULL;
+
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_next(m, pos);

@@ -1518,6 +1524,10 @@ static void *t_start(struct seq_file *m, loff_t *pos)
loff_t l;

mutex_lock(&ftrace_lock);
+
+ if (unlikely(ftrace_disabled))
+ return NULL;
+
/*
* If an lseek was done, then reset and start from beginning.
*/
@@ -1636,8 +1646,6 @@ static void ftrace_filter_reset(int enable)
if (enable)
ftrace_filtered = 0;
do_for_each_ftrace_rec(pg, rec) {
- if (rec->flags & FTRACE_FL_FAILED)
- continue;
rec->flags &= ~type;
} while_for_each_ftrace_rec();
mutex_unlock(&ftrace_lock);
@@ -1767,9 +1775,6 @@ static int ftrace_match_records(char *buff, int len, int enable)
mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {

- if (rec->flags & FTRACE_FL_FAILED)
- continue;
-
if (ftrace_match_record(rec, search, search_len, type)) {
if (not)
rec->flags &= ~flag;
@@ -1837,10 +1842,11 @@ static int ftrace_match_module_records(char *buff, char *mod, int enable)
}

mutex_lock(&ftrace_lock);
- do_for_each_ftrace_rec(pg, rec) {

- if (rec->flags & FTRACE_FL_FAILED)
- continue;
+ if (unlikely(ftrace_disabled))
+ goto out_unlock;
+
+ do_for_each_ftrace_rec(pg, rec) {

if (ftrace_match_module_record(rec, mod,
search, search_len, type)) {
@@ -1854,6 +1860,7 @@ static int ftrace_match_module_records(char *buff, char *mod, int enable)
ftrace_filtered = 1;

} while_for_each_ftrace_rec();
+ out_unlock:
mutex_unlock(&ftrace_lock);

return found;
@@ -2008,10 +2015,11 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
return -EINVAL;

mutex_lock(&ftrace_lock);
- do_for_each_ftrace_rec(pg, rec) {

- if (rec->flags & FTRACE_FL_FAILED)
- continue;
+ if (unlikely(ftrace_disabled))
+ goto out_unlock;
+
+ do_for_each_ftrace_rec(pg, rec) {

if (!ftrace_match_record(rec, search, len, type))
continue;
@@ -2218,6 +2226,10 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,

mutex_lock(&ftrace_regex_lock);

+ ret = -ENODEV;
+ if (unlikely(ftrace_disabled))
+ goto out_unlock;
+
if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;
iter = m->private;
@@ -2545,9 +2557,6 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
bool exists;
int i;

- if (ftrace_disabled)
- return -ENODEV;
-
/* decode regex */
type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
if (!not && *idx >= FTRACE_GRAPH_MAX_FUNCS)
@@ -2556,9 +2565,15 @@ ftrace_set_func(unsigned long *array, int *idx, char *buffer)
search_len = strlen(search);

mutex_lock(&ftrace_lock);
+
+ if (unlikely(ftrace_disabled)) {
+ mutex_unlock(&ftrace_lock);
+ return -ENODEV;
+ }
+
do_for_each_ftrace_rec(pg, rec) {

- if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
+ if (rec->flags & FTRACE_FL_FREE)
continue;

if (ftrace_match_record(rec, search, search_len, type)) {
@@ -2700,10 +2715,11 @@ void ftrace_release_mod(struct module *mod)
struct dyn_ftrace *rec;
struct ftrace_page *pg;

+ mutex_lock(&ftrace_lock);
+
if (ftrace_disabled)
- return;
+ goto out_unlock;

- mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {
if (within_module_core(rec->ip, mod)) {
/*
@@ -2714,6 +2730,7 @@ void ftrace_release_mod(struct module *mod)
ftrace_free_rec(rec);
}
} while_for_each_ftrace_rec();
+ out_unlock:
mutex_unlock(&ftrace_lock);
}

@@ -3108,16 +3125,17 @@ void ftrace_kill(void)
*/
int register_ftrace_function(struct ftrace_ops *ops)
{
- int ret;
-
- if (unlikely(ftrace_disabled))
- return -1;
+ int ret = -1;

mutex_lock(&ftrace_lock);

+ if (unlikely(ftrace_disabled))
+ goto out_unlock;
+
ret = __register_ftrace_function(ops);
ftrace_startup(0);

+ out_unlock:
mutex_unlock(&ftrace_lock);
return ret;
}
@@ -3145,14 +3163,14 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
- int ret;
-
- if (unlikely(ftrace_disabled))
- return -ENODEV;
+ int ret = -ENODEV;

mutex_lock(&ftrace_lock);

- ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ if (unlikely(ftrace_disabled))
+ goto out;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);

if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
goto out;
--
1.7.2.3



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