Messages in this thread Patch in this message | | | From | "Ziqian SUN (Zamir)" <> | Subject | [PATCH v3] tracing: Ignore mmiotrace from kernel commandline | Date | Mon, 11 Sep 2017 14:26:35 +0800 |
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From: "Ziqian SUN (Zamir)" <zsun@redhat.com>
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.
Signed-off-by: Ziqian SUN (Zamir) <zsun@redhat.com> -- v1 -> v2 : remove unessential comment v2 -> v3 : Use tracer struct instead of a separate list to store noboot --- 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 5360b7a..48c474f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5358,6 +5358,13 @@ 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 fb5d54d..652c682 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -444,6 +444,8 @@ struct tracer { #ifdef CONFIG_TRACER_MAX_TRACE bool use_max_tr; #endif + /* True if tracer cannot be enabled in kernel param */ + bool noboot; }; diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c index cd7480d..dca78fc 100644 --- a/kernel/trace/trace_mmiotrace.c +++ b/kernel/trace/trace_mmiotrace.c @@ -282,6 +282,7 @@ static enum print_line_t mmio_print_line(struct trace_iterator *iter) .close = mmio_close, .read = mmio_read, .print_line = mmio_print_line, + .noboot = true, }; __init static int init_mmio_trace(void) -- 1.8.3.1
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