tracing: Add trace_options kernel command line parameter
Add trace_options to the kernel command line parameter to be able to
set options at early boot. For example, to enable stack dumps of
events, add the following:
trace_options=stacktrace
This along with the trace_event option, you can get not only
traces of the events but also the stack dumps with them.
Requested-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 37d1c70..c1434b5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -155,6 +155,18 @@
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
+
+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)
+{
+ strncpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
+ trace_boot_options = trace_boot_options_buf;
+ return 0;
+}
+__setup("trace_options=", set_trace_boot_options);
+
unsigned long long ns2usecs(cycle_t nsec)
{
nsec += 500;
@@ -2838,24 +2850,14 @@
trace_printk_start_stop_comm(enabled);
}
-static ssize_t
-tracing_trace_options_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *ppos)
+static int trace_set_options(char *option)
{
- char buf[64];
char *cmp;
int neg = 0;
- int ret;
+ int ret = 0;
int i;
- if (cnt >= sizeof(buf))
- return -EINVAL;
-
- if (copy_from_user(&buf, ubuf, cnt))
- return -EFAULT;
-
- buf[cnt] = 0;
- cmp = strstrip(buf);
+ cmp = strstrip(option);
if (strncmp(cmp, "no", 2) == 0) {
neg = 1;
@@ -2874,10 +2876,25 @@
mutex_lock(&trace_types_lock);
ret = set_tracer_option(current_trace, cmp, neg);
mutex_unlock(&trace_types_lock);
- if (ret)
- return ret;
}
+ return ret;
+}
+
+static ssize_t
+tracing_trace_options_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ trace_set_options(buf);
+
*ppos += cnt;
return cnt;
@@ -5133,6 +5150,13 @@
register_die_notifier(&trace_die_notifier);
+ while (trace_boot_options) {
+ char *option;
+
+ option = strsep(&trace_boot_options, ",");
+ trace_set_options(option);
+ }
+
return 0;
out_free_cpumask: