[PATCH] perf tool: Fix ppid for synthesized fork events

From: David Ahern
Date: Thu Mar 19 2015 - 13:41:38 EST


363b785f38 added synthesized fork events and set a thread's parent id
to itself. Since we are already processing /proc/<pid>/status the ppid
can be determined properly. Make it so.

Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
---
tools/perf/util/event.c | 94 ++++++++++++++++++++++++++++---------------------
1 file changed, 53 insertions(+), 41 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index d5efa5092ce6..62bf7b71ac7b 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -49,23 +49,26 @@ static struct perf_sample synth_sample = {
.period = 1,
};

-static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
+static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len,
+ pid_t *tgid, pid_t *ppid)
{
char filename[PATH_MAX];
char bf[BUFSIZ];
FILE *fp;
size_t size = 0;
- pid_t tgid = -1;
+
+ *tgid = -1;
+ *ppid = -1;

snprintf(filename, sizeof(filename), "/proc/%d/status", pid);

fp = fopen(filename, "r");
if (fp == NULL) {
pr_debug("couldn't open %s\n", filename);
- return 0;
+ return -1;
}

- while (!comm[0] || (tgid < 0)) {
+ while (!comm[0] || (*tgid < 0) || (*ppid < 0)) {
if (fgets(bf, sizeof(bf), fp) == NULL) {
pr_warning("couldn't get COMM and pgid, malformed %s\n",
filename);
@@ -86,33 +89,45 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
char *tgids = bf + 5;
while (*tgids && isspace(*tgids))
++tgids;
- tgid = atoi(tgids);
+ *tgid = atoi(tgids);
+
+ } else if (memcmp(bf, "PPid:", 5) == 0) {
+ char *ppids = bf + 5;
+
+ while (*ppids && isspace(*ppids))
+ ++ppids;
+ *ppid = atoi(ppids);
}
}

fclose(fp);

- return tgid;
+ return 0;
}

-static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
- struct machine *machine)
+static int perf_event__prepare_comm(union perf_event *event, pid_t pid,
+ struct machine *machine,
+ pid_t *tgid, pid_t *ppid)
{
size_t size;
- pid_t tgid;
+
+ *ppid = -1;

memset(&event->comm, 0, sizeof(event->comm));

- if (machine__is_host(machine))
- tgid = perf_event__get_comm_tgid(pid, event->comm.comm,
- sizeof(event->comm.comm));
- else
- tgid = machine->pid;
+ if (machine__is_host(machine)) {
+ if (perf_event__get_comm_ids(pid, event->comm.comm,
+ sizeof(event->comm.comm),
+ tgid, ppid) != 0) {
+ return -1;
+ }
+ } else
+ *tgid = machine->pid;

- if (tgid < 0)
- goto out;
+ if (*tgid < 0)
+ return -1;

- event->comm.pid = tgid;
+ event->comm.pid = *tgid;
event->comm.header.type = PERF_RECORD_COMM;

size = strlen(event->comm.comm) + 1;
@@ -122,36 +137,35 @@ static pid_t perf_event__prepare_comm(union perf_event *event, pid_t pid,
(sizeof(event->comm.comm) - size) +
machine->id_hdr_size);
event->comm.tid = pid;
-out:
- return tgid;
+
+ return 0;
}

-static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
- union perf_event *event, pid_t pid,
- perf_event__handler_t process,
- struct machine *machine)
+static int perf_event__synthesize_comm(struct perf_tool *tool,
+ union perf_event *event, pid_t pid,
+ perf_event__handler_t process,
+ struct machine *machine,
+ pid_t *tgid, pid_t *ppid)
{
- pid_t tgid = perf_event__prepare_comm(event, pid, machine);
-
- if (tgid == -1)
- goto out;
+ if (perf_event__prepare_comm(event, pid, machine, tgid, ppid) != 0)
+ return -1;

if (process(tool, event, &synth_sample, machine) != 0)
return -1;

-out:
- return tgid;
+ return 0;
}

static int perf_event__synthesize_fork(struct perf_tool *tool,
- union perf_event *event, pid_t pid,
- pid_t tgid, perf_event__handler_t process,
+ union perf_event *event,
+ pid_t pid, pid_t tgid, pid_t ppid,
+ perf_event__handler_t process,
struct machine *machine)
{
memset(&event->fork, 0, sizeof(event->fork) + machine->id_hdr_size);

- event->fork.ppid = tgid;
- event->fork.ptid = tgid;
+ event->fork.ppid = ppid;
+ event->fork.ptid = ppid;
event->fork.pid = tgid;
event->fork.tid = pid;
event->fork.header.type = PERF_RECORD_FORK;
@@ -343,14 +357,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
char filename[PATH_MAX];
DIR *tasks;
struct dirent dirent, *next;
- pid_t tgid;
+ pid_t tgid, ppid;

/* special case: only send one comm event using passed in pid */
if (!full) {
- tgid = perf_event__synthesize_comm(tool, comm_event, pid,
- process, machine);
-
- if (tgid == -1)
+ if (perf_event__synthesize_comm(tool, comm_event, pid,
+ process, machine, &tgid, &ppid) != 0)
return -1;

return perf_event__synthesize_mmap_events(tool, mmap_event, pid, tgid,
@@ -378,12 +390,12 @@ static int __event__synthesize_thread(union perf_event *comm_event,
if (*end)
continue;

- tgid = perf_event__prepare_comm(comm_event, _pid, machine);
- if (tgid == -1)
+ if (perf_event__prepare_comm(comm_event, _pid, machine,
+ &tgid, &ppid) != 0)
return -1;

if (perf_event__synthesize_fork(tool, fork_event, _pid, tgid,
- process, machine) < 0)
+ ppid, process, machine) < 0)
return -1;
/*
* Send the prepared comm event
--
2.2.1

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