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Subject[tip:tracing/core] tracing/events: clean up for ftrace_set_clr_event()
Commit-ID:  8f31bfe538ebafac187d2d4465a92e1d9ee6d8c2
Gitweb: http://git.kernel.org/tip/8f31bfe538ebafac187d2d4465a92e1d9ee6d8c2
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Fri, 8 May 2009 10:31:42 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 8 May 2009 14:00:35 +0200

tracing/events: clean up for ftrace_set_clr_event()

Add a helper function __ftrace_set_clr_event(), and replace some
ftrace_set_clr_event() calls with this helper, thus we don't need any
kstrdup() or kmalloc().

As a side effect, this patch fixes an issue in self tests code, which is
similar to the one fixed in commit d6bf81ef0f7474434c2a049e8bf3c9146a14dd96
("tracing: append ":*" to internal setting of system events")

It's a small issue and won't cause any bug in fact, but we should do things
right anyway.

[ Impact: prevent spurious event-enabling in tracing self-tests ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A03998E.3020503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/trace/trace_events.c | 126 ++++++++++++++++---------------------------
1 files changed, 46 insertions(+), 80 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 8d0fae3..45f1099 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -111,11 +111,44 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
}
}

-static int ftrace_set_clr_event(char *buf, int set)
+/*
+ * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
+ */
+static int __ftrace_set_clr_event(const char *match, const char *sub,
+ const char *event, int set)
{
struct ftrace_event_call *call;
+ int ret;
+
+ mutex_lock(&event_mutex);
+ list_for_each_entry(call, &ftrace_events, list) {
+
+ if (!call->name || !call->regfunc)
+ continue;
+
+ if (match &&
+ strcmp(match, call->name) != 0 &&
+ strcmp(match, call->system) != 0)
+ continue;
+
+ if (sub && strcmp(sub, call->system) != 0)
+ continue;
+
+ if (event && strcmp(event, call->name) != 0)
+ continue;
+
+ ftrace_event_enable_disable(call, set);
+
+ ret = 0;
+ }
+ mutex_unlock(&event_mutex);
+
+ return ret;
+}
+
+static int ftrace_set_clr_event(char *buf, int set)
+{
char *event = NULL, *sub = NULL, *match;
- int ret = -EINVAL;

/*
* The buf format can be <subsystem>:<event-name>
@@ -141,30 +174,7 @@ static int ftrace_set_clr_event(char *buf, int set)
event = NULL;
}

- mutex_lock(&event_mutex);
- list_for_each_entry(call, &ftrace_events, list) {
-
- if (!call->name || !call->regfunc)
- continue;
-
- if (match &&
- strcmp(match, call->name) != 0 &&
- strcmp(match, call->system) != 0)
- continue;
-
- if (sub && strcmp(sub, call->system) != 0)
- continue;
-
- if (event && strcmp(event, call->name) != 0)
- continue;
-
- ftrace_event_enable_disable(call, set);
-
- ret = 0;
- }
- mutex_unlock(&event_mutex);
-
- return ret;
+ return __ftrace_set_clr_event(match, sub, event, set);
}

/* 128 should be much more than enough */
@@ -408,18 +418,14 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
struct ftrace_event_call *call;
char buf[2];
int set = -1;
- int all = 0;
int ret;

- if (system[0] == '*')
- all = 1;
-
mutex_lock(&event_mutex);
list_for_each_entry(call, &ftrace_events, list) {
if (!call->name || !call->regfunc)
continue;

- if (!all && strcmp(call->system, system) != 0)
+ if (system && strcmp(call->system, system) != 0)
continue;

/*
@@ -480,7 +486,6 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
{
const char *system = filp->private_data;
unsigned long val;
- char *command;
char buf[64];
ssize_t ret;

@@ -500,30 +505,16 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
if (ret < 0)
return ret;

- switch (val) {
- case 0:
- case 1:
- break;
-
- default:
+ if (val != 0 && val != 1)
return -EINVAL;
- }

- /* +3 for the ":*\0" */
- command = kmalloc(strlen(system)+3, GFP_KERNEL);
- if (!command)
- return -ENOMEM;
- sprintf(command, "%s:*", system);
-
- ret = ftrace_set_clr_event(command, val);
+ ret = __ftrace_set_clr_event(NULL, system, NULL, val);
if (ret)
- goto out_free;
+ goto out;

ret = cnt;

- out_free:
- kfree(command);
-
+out:
*ppos += cnt;

return ret;
@@ -1181,7 +1172,7 @@ static __init int event_trace_init(void)
&ftrace_show_header_fops);

trace_create_file("enable", 0644, d_events,
- "*", &ftrace_system_enable_fops);
+ NULL, &ftrace_system_enable_fops);

for_each_event(call, __start_ftrace_events, __stop_ftrace_events) {
/* The linker may leave blanks */
@@ -1259,7 +1250,6 @@ static __init void event_trace_self_tests(void)
{
struct ftrace_event_call *call;
struct event_subsystem *system;
- char *sysname;
int ret;

pr_info("Running tests on trace events:\n");
@@ -1305,14 +1295,7 @@ static __init void event_trace_self_tests(void)

pr_info("Testing event system %s: ", system->name);

- /* ftrace_set_clr_event can modify the name passed in. */
- sysname = kstrdup(system->name, GFP_KERNEL);
- if (WARN_ON(!sysname)) {
- pr_warning("Can't allocate memory, giving up!\n");
- return;
- }
- ret = ftrace_set_clr_event(sysname, 1);
- kfree(sysname);
+ ret = __ftrace_set_clr_event(NULL, system->name, NULL, 1);
if (WARN_ON_ONCE(ret)) {
pr_warning("error enabling system %s\n",
system->name);
@@ -1321,14 +1304,7 @@ static __init void event_trace_self_tests(void)

event_test_stuff();

- sysname = kstrdup(system->name, GFP_KERNEL);
- if (WARN_ON(!sysname)) {
- pr_warning("Can't allocate memory, giving up!\n");
- return;
- }
- ret = ftrace_set_clr_event(sysname, 0);
- kfree(sysname);
-
+ ret = __ftrace_set_clr_event(NULL, system->name, NULL, 0);
if (WARN_ON_ONCE(ret))
pr_warning("error disabling system %s\n",
system->name);
@@ -1341,15 +1317,8 @@ static __init void event_trace_self_tests(void)
pr_info("Running tests on all trace events:\n");
pr_info("Testing all events: ");

- sysname = kmalloc(4, GFP_KERNEL);
- if (WARN_ON(!sysname)) {
- pr_warning("Can't allocate memory, giving up!\n");
- return;
- }
- memcpy(sysname, "*:*", 4);
- ret = ftrace_set_clr_event(sysname, 1);
+ ret = __ftrace_set_clr_event(NULL, NULL, NULL, 1);
if (WARN_ON_ONCE(ret)) {
- kfree(sysname);
pr_warning("error enabling all events\n");
return;
}
@@ -1357,10 +1326,7 @@ static __init void event_trace_self_tests(void)
event_test_stuff();

/* reset sysname */
- memcpy(sysname, "*:*", 4);
- ret = ftrace_set_clr_event(sysname, 0);
- kfree(sysname);
-
+ ret = __ftrace_set_clr_event(NULL, NULL, NULL, 0);
if (WARN_ON_ONCE(ret)) {
pr_warning("error disabling all events\n");
return;

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