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authorSteven Rostedt <srostedt@redhat.com>2012-11-01 22:56:07 -0400
committerSteven Rostedt <rostedt@goodmis.org>2012-11-02 10:21:53 -0400
commit7bcfaf54f591a0775254c4ea679faf615152ee3a (patch)
tree697df255d0d3961b568c8e17f527f52175d7c3fa
parent0d5c6e1c19bab82fad4837108c2902f557d62a04 (diff)
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>
-rw-r--r--Documentation/kernel-parameters.txt16
-rw-r--r--kernel/trace/trace.c54
2 files changed, 55 insertions, 15 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9776f068306b..2b48c52464a1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2859,6 +2859,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
to facilitate early boot debugging.
See also Documentation/trace/events.txt
+ trace_options=[option-list]
+ [FTRACE] Enable or disable tracer options at boot.
+ The option-list is a comma delimited list of options
+ that can be enabled or disabled just as if you were
+ to echo the option name into
+
+ /sys/kernel/debug/tracing/trace_options
+
+ For example, to enable stacktrace option (to dump the
+ stack trace of each event), add to the command line:
+
+ trace_options=stacktrace
+
+ See also Documentation/trace/ftrace.txt "trace options"
+ section.
+
transparent_hugepage=
[KNL]
Format: [always|madvise|never]
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 37d1c703e3ec..c1434b5ce4d1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -155,6 +155,18 @@ static int __init set_ftrace_dump_on_oops(char *str)
}
__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 @@ static void set_tracer_flags(unsigned int mask, int enabled)
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 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
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 @@ __init static int tracer_alloc_buffers(void)
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: