perf tools: Fix ppid for synthesized fork events

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@gmail.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Mario <jmario@redhat.com>
Link: http://lkml.kernel.org/r/1427747758-18510-2-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 50 insertions, 33 deletions

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 023dd3548a94..5516236df6ab 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -51,29 +51,32 @@ static struct perf_sample synth_sample = {
 
 /*
  * Assumes that the first 4095 bytes of /proc/pid/stat contains
- * the comm and tgid.
+ * the comm, tgid and ppid.
  */
-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[4096];
         int fd;
         size_t size = 0, n;
-        pid_t tgid = -1;
-        char *nl, *name, *tgids;
+        char *nl, *name, *tgids, *ppids;
+
+        *tgid = -1;
+        *ppid = -1;
 
         snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
         fd = open(filename, O_RDONLY);
         if (fd < 0) {
                 pr_debug("couldn't open %s\n", filename);
-                return 0;
+                return -1;
         }
 
         n = read(fd, bf, sizeof(bf) - 1);
         close(fd);
         if (n <= 0) {
-                pr_warning("Couldn't get COMM and tgid for pid %d\n",
+                pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n",
                            pid);
                 return -1;
         }
@@ -81,6 +84,7 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
         name = strstr(bf, "Name:");
         tgids = strstr(bf, "Tgid:");
+        ppids = strstr(bf, "PPid:");
 
         if (name) {
                 name += 5;  /* strlen("Name:") */
@@ -103,32 +107,45 @@ static pid_t perf_event__get_comm_tgid(pid_t pid, char *comm, size_t len)
 
         if (tgids) {
                 tgids += 5;  /* strlen("Tgid:") */
-                tgid = atoi(tgids);
+                *tgid = atoi(tgids);
         } else {
                 pr_debug("Tgid: string not found for pid %d\n", pid);
         }
 
-        return tgid;
+        if (ppids) {
+                ppids += 5;  /* strlen("PPid:") */
+                *ppid = atoi(ppids);
+        } else {
+                pr_debug("PPid: string not found for pid %d\n", pid);
+        }
+
+        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;
@@ -138,8 +155,8 @@ 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,
@@ -147,27 +164,27 @@ static pid_t perf_event__synthesize_comm(struct perf_tool *tool,
                                          perf_event__handler_t process,
                                          struct machine *machine)
 {
-        pid_t tgid = perf_event__prepare_comm(event, pid, machine);
+        pid_t tgid, ppid;
 
-        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;
 }
 
 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;
@@ -359,7 +376,7 @@ 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) {
@@ -394,12 +411,12 @@ 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