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Date: Fri, 8 May 2009 12:50:16 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: Li Zefan <lizf@...fujitsu.com>
Cc: Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] tracing/events: clean up for ftrace_set_clr_event()
On Fri, May 08, 2009 at 10:31:42AM +0800, Li Zefan wrote:
> 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: clean up ]
If this fixes an issue like you described, then it's more than a cleanup :)
>
> Signed-off-by: Li Zefan <lizf@...fujitsu.com>
> ---
> 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;
Neat: You can simply use !strcmp(...)
> +
> + 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;
> --
> 1.5.4.rc3
>
I haven't reviewed deeply, but it looks good and bring a rather
good simplification.
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