On 09/11/2017 02:26 PM, Ziqian SUN (Zamir) wrote:
From: "Ziqian SUN (Zamir)" <[email protected]>
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) <[email protected]>
--
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);
I feel the core trace printed by WARN is not so meaningful, so I use
pr_warn instead.
+ 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)
This patch passed my own test on top of Fedora kernel 4.13.0-1.fc26.x86_64.
--
Ziqian SUN (Zamir)
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Red Hat Software (Beijing) Co.,Ltd
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Tel: +86 10 65627458
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