[PATCH 23/30] perf thread: Introduce method to set comm from /proc/pid/self

From: Arnaldo Carvalho de Melo
Date: Wed Apr 27 2016 - 10:35:20 EST


From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Will be used for lazy comm loading in 'perf trace'.

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Milian Wolff <milian.wolff@xxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-7ogbkuoka1y2qsmcckqxvl5m@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/thread.c | 19 +++++++++++++++++++
tools/perf/util/thread.h | 2 ++
2 files changed, 21 insertions(+)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index de2036d1251b..45fcb715a36b 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -10,6 +10,8 @@
#include "comm.h"
#include "unwind.h"

+#include <api/fs/fs.h>
+
int thread__init_map_groups(struct thread *thread, struct machine *machine)
{
struct thread *leader;
@@ -153,6 +155,23 @@ int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
return 0;
}

+int thread__set_comm_from_proc(struct thread *thread)
+{
+ char path[64];
+ char *comm = NULL;
+ size_t sz;
+ int err = -1;
+
+ if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
+ thread->pid_, thread->tid) >= (int)sizeof(path)) &&
+ procfs__read_str(path, &comm, &sz) == 0) {
+ comm[sz - 1] = '\0';
+ err = thread__set_comm(thread, comm, 0);
+ }
+
+ return err;
+}
+
const char *thread__comm_str(const struct thread *thread)
{
const struct comm *comm = thread__comm(thread);
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index e214207bb13a..45fba13c800b 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -71,6 +71,8 @@ static inline int thread__set_comm(struct thread *thread, const char *comm,
return __thread__set_comm(thread, comm, timestamp, false);
}

+int thread__set_comm_from_proc(struct thread *thread);
+
int thread__comm_len(struct thread *thread);
struct comm *thread__comm(const struct thread *thread);
struct comm *thread__exec_comm(const struct thread *thread);
--
2.5.5