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authorSteven Rostedt <srostedt@redhat.com>2009-03-02 10:53:15 -0500
committerSteven Rostedt <srostedt@redhat.com>2009-03-02 10:53:15 -0500
commitd20e3b03842bfeb9d21817ff19054c277cc3eac0 (patch)
tree5de7ef8a95f9391a264df358336842c9301f3868
parentf2034f1e1adaac6713a6d48b5a2d4f3aa3e63ccb (diff)
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@gmail.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
-rw-r--r--include/trace/sched_event_types.h7
-rw-r--r--kernel/trace/trace_events_stage_1.h2
-rw-r--r--kernel/trace/trace_events_stage_2.h4
-rw-r--r--kernel/trace/trace_events_stage_3.h14
4 files changed, 26 insertions, 1 deletions
diff --git a/include/trace/sched_event_types.h b/include/trace/sched_event_types.h
index ba059c10b58..a6de5c1601a 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 fd3bf9382d3..3830a731424 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 3eaaef5f19e..dc79fe3a2ec 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 7a161c49deb..2ab65e95822 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)) \