[PATCH 08/15] ftrace: convert ftrace_lock from a spinlock to mutex

Steven Rostedt
2009-02-17T05:42:48Z

[-- Attachment #1: 0008-ftrace-convert-ftrace_lock-from-a-spinlock-to-mutex.patch --]
[-- Type: text/plain, Size: 5480 bytes --]

From: Steven Rostedt <srostedt@redhat.com>

Impact: clean up

The older versions of ftrace required doing the ftrace list
search under atomic context. Now all the calls are in non-atomic
context. There is no reason to keep the ftrace_lock as a spinlock.

This patch converts it to a mutex.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/trace/ftrace.c | 51 ++++++++++++++++++------------------------------
1 files changed, 19 insertions(+), 32 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 45a44c4..4771732 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -61,7 +61,7 @@ int function_trace_stop;
*/
static int ftrace_disabled __read_mostly;

-static DEFINE_SPINLOCK(ftrace_lock);
+static DEFINE_MUTEX(ftrace_lock);
static DEFINE_MUTEX(ftrace_sysctl_lock);
static DEFINE_MUTEX(ftrace_start_lock);

@@ -134,8 +134,7 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)

static int __register_ftrace_function(struct ftrace_ops *ops)
{
- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);

ops->next = ftrace_list;
/*
@@ -172,7 +171,7 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
#endif
}

- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);

return 0;
}
@@ -182,8 +181,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
struct ftrace_ops **p;
int ret = 0;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);

/*
* If we are removing the last function, then simply point
@@ -224,7 +222,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
}

out:
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);

return ret;
}
@@ -233,8 +231,7 @@ static void ftrace_update_pid_func(void)
{
ftrace_func_t func;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);

if (ftrace_trace_function == ftrace_stub)
goto out;
@@ -256,7 +253,7 @@ static void ftrace_update_pid_func(void)
#endif

out:
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);
}

#ifdef CONFIG_DYNAMIC_FTRACE
@@ -358,15 +355,12 @@ void ftrace_release(void *start, unsigned long size)
if (ftrace_disabled || !start)
return;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
-
+ mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {
if ((rec->ip >= s) && (rec->ip < e))
ftrace_free_rec(rec);
} while_for_each_ftrace_rec();
-
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);
}

static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
@@ -803,8 +797,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
if (iter->flags & FTRACE_ITER_PRINTALL)
return NULL;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);
retry:
if (iter->idx >= iter->pg->index) {
if (iter->pg->next) {
@@ -833,7 +826,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
goto retry;
}
}
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);

return rec;
}
@@ -962,8 +955,7 @@ static void ftrace_filter_reset(int enable)
struct dyn_ftrace *rec;
unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);
if (enable)
ftrace_filtered = 0;
do_for_each_ftrace_rec(pg, rec) {
@@ -971,8 +963,7 @@ static void ftrace_filter_reset(int enable)
continue;
rec->flags &= ~type;
} while_for_each_ftrace_rec();
-
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);
}

static int
@@ -1151,8 +1142,7 @@ static void ftrace_match_records(char *buff, int len, int enable)

search_len = strlen(search);

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {

if (rec->flags & FTRACE_FL_FAILED)
@@ -1171,7 +1161,7 @@ static void ftrace_match_records(char *buff, int len, int enable)
if (enable && (rec->flags & FTRACE_FL_FILTER))
ftrace_filtered = 1;
} while_for_each_ftrace_rec();
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);
}

static int
@@ -1218,8 +1208,7 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable)
search_len = strlen(search);
}

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
+ mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {

if (rec->flags & FTRACE_FL_FAILED)
@@ -1236,7 +1225,7 @@ static void ftrace_match_module_records(char *buff, char *mod, int enable)
ftrace_filtered = 1;

} while_for_each_ftrace_rec();
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);
}

/*
@@ -1676,9 +1665,7 @@ ftrace_set_func(unsigned long *array, int idx, char *buffer)
if (ftrace_disabled)
return -ENODEV;

- /* should not be called from interrupt context */
- spin_lock(&ftrace_lock);
-
+ mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {

if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
@@ -1699,7 +1686,7 @@ ftrace_set_func(unsigned long *array, int idx, char *buffer)
}
} while_for_each_ftrace_rec();
out:
- spin_unlock(&ftrace_lock);
+ mutex_unlock(&ftrace_lock);

return found ? 0 : -EINVAL;
}
--
1.5.6.5

--