tracing/filters: add TRACE_EVENT_FORMAT_NOFILTER event macro

Frederic Weisbecker suggested that the trace_special event shouldn't be
filterable; this patch adds a TRACE_EVENT_FORMAT_NOFILTER event macro
that allows an event format to be exported without having a filter
attached, and removes filtering from the trace_special event.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 36 insertions, 3 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 962e6179994a..c209d214169c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1064,7 +1064,6 @@ ftrace_trace_special(void *__tr,
                      unsigned long arg1, unsigned long arg2, unsigned long arg3,
                      int pc)
 {
-        struct ftrace_event_call *call = &event_special;
         struct ring_buffer_event *event;
         struct trace_array *tr = __tr;
         struct special_entry *entry;
@@ -1077,7 +1076,6 @@ ftrace_trace_special(void *__tr,
         entry->arg1                     = arg1;
         entry->arg2                     = arg2;
         entry->arg3                     = arg3;
-        filter_check_discard(call, entry, event);
         trace_buffer_unlock_commit(tr, event, 0, pc);
 }
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e7737281953f..3cf856fa597b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -915,6 +915,8 @@ do {									\
 #undef TRACE_EVENT_FORMAT
 #define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt)      \
         extern struct ftrace_event_call event_##call;
+#undef TRACE_EVENT_FORMAT_NOFILTER
+#define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct, tpfmt)
 #include "trace_event_types.h"
 
 #endif /* _LINUX_KERNEL_TRACE_H */
diff --git a/kernel/trace/trace_event_types.h b/kernel/trace/trace_event_types.h
index 95b147aac229..cfcecc4fd86d 100644
--- a/kernel/trace/trace_event_types.h
+++ b/kernel/trace/trace_event_types.h
@@ -57,7 +57,7 @@ TRACE_EVENT_FORMAT(context_switch, TRACE_CTX, ctx_switch_entry, ignore,
         TP_RAW_FMT("%u:%u:%u  ==+ %u:%u:%u [%03u]")
 );
 
-TRACE_EVENT_FORMAT(special, TRACE_SPECIAL, special_entry, ignore,
+TRACE_EVENT_FORMAT_NOFILTER(special, TRACE_SPECIAL, special_entry, ignore,
         TRACE_STRUCT(
                 TRACE_FIELD(unsigned long, arg1, arg1)
                 TRACE_FIELD(unsigned long, arg2, arg2)
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index f4e46616c48e..77c494f5e1d6 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -65,6 +65,22 @@ ftrace_format_##call(struct trace_seq *s)				\
         return ret;                                                     \
 }
 
+#undef TRACE_EVENT_FORMAT_NOFILTER
+#define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct,    \
+                                    tpfmt)                              \
+static int                                                              \
+ftrace_format_##call(struct trace_seq *s)                               \
+{                                                                       \
+        struct args field;                                              \
+        int ret;                                                        \
+                                                                        \
+        tstruct;                                                        \
+                                                                        \
+        trace_seq_printf(s, "\nprint fmt: \"%s\"\n", tpfmt);            \
+                                                                        \
+        return ret;                                                     \
+}
+
 #include "trace_event_types.h"
 
 #undef TRACE_ZERO_CHAR
@@ -109,6 +125,19 @@ static int ftrace_raw_init_event_##call(void)				\
         return 0;                                                       \
 }                                                                       \
 
+#undef TRACE_EVENT_FORMAT_NOFILTER
+#define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct,    \
+                                    tpfmt)                              \
+                                                                        \
+struct ftrace_event_call __used                                         \
+__attribute__((__aligned__(4)))                                         \
+__attribute__((section("_ftrace_events"))) event_##call = {             \
+        .name                   = #call,                                \
+        .id                     = proto,                                \
+        .system                 = __stringify(TRACE_SYSTEM),            \
+        .show_format            = ftrace_format_##call,                 \
+};
+
 #include "trace_event_types.h"
 
 #undef TRACE_FIELD
@@ -150,4 +179,8 @@ ftrace_define_fields_##call(void)					\
         return ret;                                                     \
 }
 
+#undef TRACE_EVENT_FORMAT_NOFILTER
+#define TRACE_EVENT_FORMAT_NOFILTER(call, proto, args, fmt, tstruct,    \
+                                    tpfmt)
+
 #include "trace_event_types.h"