Commit-ID: d20e3b03842bfeb9d21817ff19054c277cc3eac0
Gitweb: http://git.kernel.org/tip/d20e3b03842bfeb9d21817ff19054c277cc3eac0
Author: Steven Rostedt <srostedt@xxxxxxxxxx>
AuthorDate: Mon, 2 Mar 2009 10:53:15 -0500
Commit: Steven Rostedt <srostedt@xxxxxxxxxx>
CommitDate: Mon, 2 Mar 2009 10:53:15 -0500
tracing: add TRACE_FIELD_SPECIAL to record complex entries
Tom Zanussi pointed out that the simple TRACE_FIELD was not enough to
record trace data that required memcpy. This patch addresses this issue
by adding a TRACE_FIELD_SPECIAL. The format is similar to TRACE_FIELD
but looks like so:
TRACE_FIELD_SPECIAL(type_item, item, cmd)
What TRACE_FIELD gave was:
TRACE_FIELD(type, item, assign)
The TRACE_FIELD would be used in declaring a structure:
struct {
type item;
};
And later assign it via:
entry->item = assign;
What TRACE_FIELD_SPECIAL gives us is:
In the declaration of the structure:
struct {
type_item;
};
And the assignment:
cmd;
This change log will explain the one example used in the patch:
TRACE_EVENT_FORMAT(sched_switch,
TPPROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TPARGS(rq, prev, next),
TPFMT("task %s:%d ==> %s:%d",
prev->comm, prev->pid, next->comm, next->pid),
TRACE_STRUCT(
TRACE_FIELD(pid_t, prev_pid, prev->pid)
TRACE_FIELD(int, prev_prio, prev->prio)
TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
next_comm,
TPCMD(memcpy(TRACE_ENTRY->next_comm,
next->comm,
TASK_COMM_LEN)))
TRACE_FIELD(pid_t, next_pid, next->pid)
TRACE_FIELD(int, next_prio, next->prio)
),
TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
);
The struct will be create as:
struct {
pid_t prev_pid;
int prev_prio;
char next_comm[TASK_COMM_LEN];
pid_t next_pid;
int next_prio;
};
Note the TRACE_ENTRY in the cmd part of TRACE_SPECIAL. TRACE_ENTRY will
be set by the tracer to point to the structure inside the trace buffer.
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
memcpy(entry->next_comm, next->comm, TASK_COMM_LEN);
entry->next_pid = next->pid;
entry->next_prio = next->prio
Reported-by: Tom Zanussi <tzanussi@xxxxxxxxx>
Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
---
include/trace/sched_event_types.h | 7 ++++++-
kernel/trace/trace_events_stage_1.h | 2 ++
kernel/trace/trace_events_stage_2.h | 4 ++++
kernel/trace/trace_events_stage_3.h | 14 ++++++++++++++
4 files changed, 26 insertions(+), 1 deletions(-)
diff --git a/include/trace/sched_event_types.h b/include/trace/sched_event_types.h
index ba059c1..a6de5c1 100644
--- a/include/trace/sched_event_types.h
+++ b/include/trace/sched_event_types.h
@@ -71,10 +71,15 @@ TRACE_EVENT_FORMAT(sched_switch,
TRACE_STRUCT(
TRACE_FIELD(pid_t, prev_pid, prev->pid)
TRACE_FIELD(int, prev_prio, prev->prio)
+ TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
+ next_comm,
+ TPCMD(memcpy(TRACE_ENTRY->next_comm,
+ next->comm,
+ TASK_COMM_LEN)))
TRACE_FIELD(pid_t, next_pid, next->pid)
TRACE_FIELD(int, next_prio, next->prio)
),
- TPRAWFMT("prev %d:%d ==> next %d:%d")
+ TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
);
TRACE_EVENT_FORMAT(sched_migrate_task,
diff --git a/kernel/trace/trace_events_stage_1.h b/kernel/trace/trace_events_stage_1.h
index fd3bf93..3830a73 100644
--- a/kernel/trace/trace_events_stage_1.h
+++ b/kernel/trace/trace_events_stage_1.h
@@ -30,5 +30,7 @@
#define TRACE_FIELD(type, item, assign) \
type item;
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+ type_item;
#include <trace/trace_event_types.h>
diff --git a/kernel/trace/trace_events_stage_2.h b/kernel/trace/trace_events_stage_2.h
index 3eaaef5..dc79fe3 100644
--- a/kernel/trace/trace_events_stage_2.h
+++ b/kernel/trace/trace_events_stage_2.h
@@ -39,6 +39,10 @@
#define TRACE_FIELD(type, item, assign) \
field->item,
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+ field->item,
+
#undef TPRAWFMT
#define TPRAWFMT(args...) args
diff --git a/kernel/trace/trace_events_stage_3.h b/kernel/trace/trace_events_stage_3.h
index 7a161c4..2ab65e9 100644
--- a/kernel/trace/trace_events_stage_3.h
+++ b/kernel/trace/trace_events_stage_3.h
@@ -147,6 +147,20 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
#define TRACE_FIELD(type, item, assign)\
entry->item = assign;
+#undef TRACE_FIELD
+#define TRACE_FIELD(type, item, assign)\
+ entry->item = assign;
+
+#undef TPCMD
+#define TPCMD(cmd...) cmd
+
+#undef TRACE_ENTRY
+#define TRACE_ENTRY entry
+
+#undef TRACE_FIELD_SPECIAL
+#define TRACE_FIELD_SPECIAL(type_item, item, cmd) \
+ cmd;
+
#undef TRACE_EVENT_FORMAT
#define TRACE_EVENT_FORMAT(call, proto, args, fmt, tstruct, tpfmt) \
_TRACE_FORMAT(call, PARAMS(proto), PARAMS(args), PARAMS(fmt)) \
--
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