[PATCH 2/3] tracing: Ignore mmiotrace from kernel commandline

[Steven Rostedt]

From: "Ziqian SUN (Zamir)" 

The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in kernel
commandline. With this patch, noboot is added to the tracer struct,
and when system boot with a tracer that has noboot=true, it will print
out a warning message and continue booting.

Link: http://lkml.kernel.org/r/150595-31942-1-git-send-email-z...@redhat.com

Signed-off-by: Ziqian SUN (Zamir) 
Signed-off-by: Steven Rostedt (VMware) 
---
 kernel/trace/trace.c   | 7 +++
 kernel/trace/trace.h   | 2 ++
 kernel/trace/trace_mmiotrace.c | 1 +
 3 files changed, 10 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a7fb136da891..d3ca35f38803 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5364,6 +5364,13 @@ static int tracing_set_tracer(struct trace_array *tr, 
const char *buf)
if (t == tr->current_trace)
goto out;
 
+   /* Some tracers won't work on kernel command line */
+   if (system_state < SYSTEM_RUNNING && t->noboot) {
+   pr_warn("Tracer '%s' is not allowed on command line, ignored\n",
+   t->name);
+   goto out;
+   }
+
/* Some tracers are only allowed for the top level buffer */
if (!trace_ok_for_array(t, tr)) {
ret = -EINVAL;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fb5d54d0d1b3..652c682707cd 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -444,6 +444,8 @@ struct tracer {
 #ifdef CONFIG_TRACER_MAX_TRACE
booluse_max_tr;
 #endif
+   /* True if tracer cannot be enabled in kernel param */
+   boolnoboot;
 };
 
 
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index cd7480d0a201..dca78fc48439 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -282,6 +282,7 @@ static struct tracer mmio_tracer __read_mostly =
.close  = mmio_close,
.read   = mmio_read,
.print_line = mmio_print_line,
+   .noboot = true,
 };
 
 __init static int init_mmio_trace(void)
-- 
2.13.2

[PATCH 2/3] tracing: Ignore mmiotrace from kernel commandline

[Steven Rostedt]

From: "Ziqian SUN (Zamir)" 

The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in kernel
commandline. With this patch, noboot is added to the tracer struct,
and when system boot with a tracer that has noboot=true, it will print
out a warning message and continue booting.

Link: http://lkml.kernel.org/r/150595-31942-1-git-send-email-z...@redhat.com

Signed-off-by: Ziqian SUN (Zamir) 
Signed-off-by: Steven Rostedt (VMware) 
---
 kernel/trace/trace.c   | 7 +++
 kernel/trace/trace.h   | 2 ++
 kernel/trace/trace_mmiotrace.c | 1 +
 3 files changed, 10 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a7fb136da891..d3ca35f38803 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5364,6 +5364,13 @@ static int tracing_set_tracer(struct trace_array *tr, 
const char *buf)
if (t == tr->current_trace)
goto out;
 
+   /* Some tracers won't work on kernel command line */
+   if (system_state < SYSTEM_RUNNING && t->noboot) {
+   pr_warn("Tracer '%s' is not allowed on command line, ignored\n",
+   t->name);
+   goto out;
+   }
+
/* Some tracers are only allowed for the top level buffer */
if (!trace_ok_for_array(t, tr)) {
ret = -EINVAL;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index fb5d54d0d1b3..652c682707cd 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -444,6 +444,8 @@ struct tracer {
 #ifdef CONFIG_TRACER_MAX_TRACE
booluse_max_tr;
 #endif
+   /* True if tracer cannot be enabled in kernel param */
+   boolnoboot;
 };
 
 
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index cd7480d0a201..dca78fc48439 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -282,6 +282,7 @@ static struct tracer mmio_tracer __read_mostly =
.close  = mmio_close,
.read   = mmio_read,
.print_line = mmio_print_line,
+   .noboot = true,
 };
 
 __init static int init_mmio_trace(void)
-- 
2.13.2