[PATCH -tip 3/7] perf probe: Use the last field name as the argument name

Masami Hiramatsu
2010-03-29T20:30:55Z

Set the last field name to the argument name when the argument
is refering a data-structure member.

e.g.
./perf probe --add 'vfs_read file->f_mode'
Add new event:
probe:vfs_read (on vfs_read with f_mode=file->f_mode)

This probe records file->f_mode, but the argument name becomes "f_mode".

This enables perf-trace command to parse trace event format correctly.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
---

tools/perf/Documentation/perf-probe.txt | 2 +-
tools/perf/util/probe-event.c | 4 ++++
2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 0657cf4..d781fc5 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -87,7 +87,7 @@ Each probe argument follows below syntax.

[NAME=]LOCALVAR|$retval|%REG|@SYMBOL

-'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), or kprobe-tracer argument format (e.g. $retval, %ax, etc).
+'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)

LINE SYNTAX
-----------
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index ab6f53d..19de8b7 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -481,6 +481,10 @@ static void parse_perf_probe_arg(const char *str, struct perf_probe_arg *arg)
} while (tmp);
(*fieldp)->name = xstrdup(str);
pr_debug("%s(%d)\n", (*fieldp)->name, (*fieldp)->ref);
+
+ /* If no name is specified, set the last field name */
+ if (!arg->name)
+ arg->name = xstrdup((*fieldp)->name);
}

/* Parse perf-probe event command */