perf record: Fix .tid and .pid fill-in when synthesizing events

Noticed when trying to record events for a firefox thread. We
were synthesizing both .tid and .pid with the pid passed via
--pid.

Fix it by reading /proc/PID/status and getting the tgid
to use in .pid, .tid gets the specified "pid".

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20090811192200.GF18061@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 0345aad..30b83de 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -203,46 +203,48 @@ static void sig_atexit(void)
        kill(getpid(), signr);
 }
 
-static void pid_synthesize_comm_event(pid_t pid, int full)
+static pid_t pid_synthesize_comm_event(pid_t pid, int full)
 {
        struct comm_event comm_ev;
        char filename[PATH_MAX];
        char bf[BUFSIZ];
-       int fd;
-       size_t size;
-       char *field, *sep;
+       FILE *fp;
+       size_t size = 0;
        DIR *tasks;
        struct dirent dirent, *next;
+       pid_t tgid = 0;
 
-       snprintf(filename, sizeof(filename), "/proc/%d/stat", pid);
+       snprintf(filename, sizeof(filename), "/proc/%d/status", pid);
 
-       fd = open(filename, O_RDONLY);
-       if (fd < 0) {
+       fp = fopen(filename, "r");
+       if (fd == NULL) {
                /*
                 * We raced with a task exiting - just return:
                 */
                if (verbose)
                        fprintf(stderr, "couldn't open %s\n", filename);
-               return;
+               return 0;
        }
-       if (read(fd, bf, sizeof(bf)) < 0) {
-               fprintf(stderr, "couldn't read %s\n", filename);
-               exit(EXIT_FAILURE);
-       }
-       close(fd);
 
-       /* 9027 (cat) R 6747 9027 6747 34816 9027 ... */
        memset(&comm_ev, 0, sizeof(comm_ev));
-       field = strchr(bf, '(');
-       if (field == NULL)
-               goto out_failure;
-       sep = strchr(++field, ')');
-       if (sep == NULL)
-               goto out_failure;
-       size = sep - field;
-       memcpy(comm_ev.comm, field, size++);
-
-       comm_ev.pid = pid;
+       while (!comm_ev.comm[0] || !comm_ev.pid) {
+               if (fgets(bf, sizeof(bf), fp) == NULL)
+                       goto out_failure;
+
+               if (memcmp(bf, "Name:", 5) == 0) {
+                       char *name = bf + 5;
+                       while (*name && isspace(*name))
+                               ++name;
+                       size = strlen(name) - 1;
+                       memcpy(comm_ev.comm, name, size++);
+               } else if (memcmp(bf, "Tgid:", 5) == 0) {
+                       char *tgids = bf + 5;
+                       while (*tgids && isspace(*tgids))
+                               ++tgids;
+                       tgid = comm_ev.pid = atoi(tgids);
+               }
+       }
+
        comm_ev.header.type = PERF_EVENT_COMM;
        size = ALIGN(size, sizeof(u64));
        comm_ev.header.size = sizeof(comm_ev) - (sizeof(comm_ev.comm) - size);
@@ -251,7 +253,7 @@ static void pid_synthesize_comm_event(pid_t pid, int full)
                comm_ev.tid = pid;
 
                write_output(&comm_ev, comm_ev.header.size);
-               return;
+               goto out_fclose;
        }
 
        snprintf(filename, sizeof(filename), "/proc/%d/task", pid);
@@ -268,7 +270,10 @@ static void pid_synthesize_comm_event(pid_t pid, int full)
                write_output(&comm_ev, comm_ev.header.size);
        }
        closedir(tasks);
-       return;
+
+out_fclose:
+       fclose(fp);
+       return tgid;
 
 out_failure:
        fprintf(stderr, "couldn't get COMM and pgid, malformed %s\n",
@@ -276,7 +281,7 @@ out_failure:
        exit(EXIT_FAILURE);
 }
 
-static void pid_synthesize_mmap_samples(pid_t pid)
+static void pid_synthesize_mmap_samples(pid_t pid, pid_t tgid)
 {
        char filename[PATH_MAX];
        FILE *fp;
@@ -328,7 +333,7 @@ static void pid_synthesize_mmap_samples(pid_t pid)
                        mmap_ev.len -= mmap_ev.start;
                        mmap_ev.header.size = (sizeof(mmap_ev) -
                                               (sizeof(mmap_ev.filename) - size));
-                       mmap_ev.pid = pid;
+                       mmap_ev.pid = tgid;
                        mmap_ev.tid = pid;
 
                        write_output(&mmap_ev, mmap_ev.header.size);
@@ -347,14 +352,14 @@ static void synthesize_all(void)
 
        while (!readdir_r(proc, &dirent, &next) && next) {
                char *end;
-               pid_t pid;
+               pid_t pid, tgid;
 
                pid = strtol(dirent.d_name, &end, 10);
                if (*end) /* only interested in proper numerical dirents */
                        continue;
 
-               pid_synthesize_comm_event(pid, 1);
-               pid_synthesize_mmap_samples(pid);
+               tgid = pid_synthesize_comm_event(pid, 1);
+               pid_synthesize_mmap_samples(pid, tgid);
        }
 
        closedir(proc);
@@ -567,8 +572,8 @@ static int __cmd_record(int argc, const char **argv)
                perf_header__write(header, output);
 
        if (!system_wide) {
-               pid_synthesize_comm_event(pid, 0);
-               pid_synthesize_mmap_samples(pid);
+               pid_t tgid = pid_synthesize_comm_event(pid, 0);
+               pid_synthesize_mmap_samples(pid, tgid);
        } else
                synthesize_all();