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tracing: Apply tracer specific options from kernel command line.

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Currently, the trace_options parameter is only applied in
tracer_alloc_buffers() when global_trace.current_trace is nop_trace,
so a tracer specific option will not be applied even when the specific
tracer is also enabled from kernel command line. For example, the
'func_stack_trace' option can't be enabled with the following kernel
parameter:

  ftrace=function ftrace_filter=kfree trace_options=func_stack_trace

We can enable tracer specific options by simply apply the options again
if the specific tracer is also supplied from command line and started
in register_tracer().

To make trace_boot_options_buf can be parsed again, a comma and a space
is put back if they were replaced by strsep and strstrip respectively.

Also make register_tracer() be __init to access the __init data, and
in fact register_tracer is only called from __init code.

Link: http://lkml.kernel.org/r/1446599669-9294-1-git-send-email-hello.wjx@gmail.com

Signed-off-by: Jiaxing Wang <hello.wjx@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiaxing Wang 2015-11-04 09:14:29 +08:00 committed by Steven Rostedt
parent 627645fdb6
commit a4d1e68823
1 changed files with 36 additions and 9 deletions
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45
kernel/trace/trace.c
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@ -214,12 +214,10 @@ __setup("alloc_snapshot", boot_alloc_snapshot);
static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
static char *trace_boot_options __initdata;
static int __init set_trace_boot_options(char *str)
{
strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
trace_boot_options = trace_boot_options_buf;
return 0;
}
__setup("trace_options=", set_trace_boot_options);
@ -1223,13 +1221,15 @@ static inline int run_tracer_selftest(struct tracer *type)
static void add_tracer_options(struct trace_array *tr, struct tracer *t);
static void __init apply_trace_boot_options(void);
/**
* register_tracer - register a tracer with the ftrace system.
* @type - the plugin for the tracer
*
* Register a new plugin tracer.
*/
int register_tracer(struct tracer *type)
int __init register_tracer(struct tracer *type)
{
struct tracer *t;
int ret = 0;
@ -1288,6 +1288,9 @@ int register_tracer(struct tracer *type)
/* Do we want this tracer to start on bootup? */
tracing_set_tracer(&global_trace, type->name);
default_bootup_tracer = NULL;
apply_trace_boot_options();
/* disable other selftests, since this will break it. */
tracing_selftest_disabled = true;
#ifdef CONFIG_FTRACE_STARTUP_TEST
@ -3589,6 +3592,7 @@ static int trace_set_options(struct trace_array *tr, char *option)
int neg = 0;
int ret = -ENODEV;
int i;
size_t orig_len = strlen(option);
cmp = strstrip(option);
@ -3612,9 +3616,37 @@ static int trace_set_options(struct trace_array *tr, char *option)
mutex_unlock(&trace_types_lock);
/*
* If the first trailing whitespace is replaced with '\0' by strstrip,
* turn it back into a space.
*/
if (orig_len > strlen(option))
option[strlen(option)] = ' ';
return ret;
}
static void __init apply_trace_boot_options(void)
{
char *buf = trace_boot_options_buf;
char *option;
while (true) {
option = strsep(&buf, ",");
if (!option)
break;
if (!*option)
continue;
trace_set_options(&global_trace, option);
/* Put back the comma to allow this to be called again */
if (buf)
*(buf - 1) = ',';
}
}
static ssize_t
tracing_trace_options_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
@ -7248,12 +7280,7 @@ __init static int tracer_alloc_buffers(void)
INIT_LIST_HEAD(&global_trace.events);
list_add(&global_trace.list, &ftrace_trace_arrays);
while (trace_boot_options) {
char *option;
option = strsep(&trace_boot_options, ",");
trace_set_options(&global_trace, option);
}
apply_trace_boot_options();
register_snapshot_cmd();