Commit 9d8b172f authored Dec 09, 2015 by Masami Hiramatsu Committed by Arnaldo Carvalho de Melo Dec 10, 2015

perf tools: Make perf_session__register_idle_thread drop the refcount



Note that since the thread was already inserted to the session
list, it will be released when the session is released.
Also, in perf_session__register_idle_thread() failure path,
the thread should be put before returning.

Refcnt debugger shows that the perf_session__register_idle_thread
gets the returned thread, but the caller (__cmd_top) does not
put the returned idle thread.

  ----
  ==== [0] ====
  Unreclaimed thread@0x24e6240
  Refcount +1 => 0 at
    ./perf(thread__new+0xe5) [0x4c8a75]
    ./perf(machine__findnew_thread+0x9a) [0x4bbdba]
    ./perf(perf_session__register_idle_thread+0x28) [0x4c63c8]
    ./perf(cmd_top+0xd7d) [0x43cf6d]
    ./perf() [0x47ba35]
    ./perf(main+0x617) [0x4225b7]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f06027c5af5]
    ./perf() [0x42272d]
  Refcount +1 => 1 at
    ./perf(thread__get+0x2c) [0x4c8bcc]
    ./perf(machine__findnew_thread+0xee) [0x4bbe0e]
    ./perf(perf_session__register_idle_thread+0x28) [0x4c63c8]
    ./perf(cmd_top+0xd7d) [0x43cf6d]
    ./perf() [0x47ba35]
    ./perf(main+0x617) [0x4225b7]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f06027c5af5]
    ./perf() [0x42272d]
  Refcount +1 => 2 at
    ./perf(thread__get+0x2c) [0x4c8bcc]
    ./perf(machine__findnew_thread+0x112) [0x4bbe32]
    ./perf(perf_session__register_idle_thread+0x28) [0x4c63c8]
    ./perf(cmd_top+0xd7d) [0x43cf6d]
    ./perf() [0x47ba35]
    ./perf(main+0x617) [0x4225b7]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f06027c5af5]
    ./perf() [0x42272d]
  ----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20151209021122.10245.69707.stgit@localhost.localdomain


[ Drop the refcount in perf_session__register_idle_thread() ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 8488335c

tools/perf/builtin-top.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -964,7 +964,7 @@ static int __cmd_top(struct perf_top *top)
		if (ret)
		goto out_delete;

		if (perf_session__register_idle_thread(top->session) == NULL)
		if (perf_session__register_idle_thread(top->session) < 0)
		goto out_delete;

		machine__synthesize_threads(&top->session->machines.host, &opts->target,

tools/perf/util/session.c

+7 −4

Original line number	Diff line number	Diff line
		@@ -1311,17 +1311,20 @@ struct thread perf_session__findnew(struct perf_session session, pid_t pid)
		return machine__findnew_thread(&session->machines.host, -1, pid);
		}

		struct thread perf_session__register_idle_thread(struct perf_session session)
		int perf_session__register_idle_thread(struct perf_session *session)
		{
		struct thread *thread;
		int err = 0;

		thread = machine__findnew_thread(&session->machines.host, 0, 0);
		if (thread == NULL \|\| thread__set_comm(thread, "swapper", 0)) {
		pr_err("problem inserting idle task.\n");
		thread = NULL;
		err = -1;
		}

		return thread;
		/* machine__findnew_thread() got the thread, so put it */
		thread__put(thread);
		return err;
		}

		static void perf_session__warn_about_errors(const struct perf_session *session)
		@@ -1676,7 +1679,7 @@ int perf_session__process_events(struct perf_session *session)
		u64 size = perf_data_file__size(session->file);
		int err;

		if (perf_session__register_idle_thread(session) == NULL)
		if (perf_session__register_idle_thread(session) < 0)
		return -ENOMEM;

		if (!perf_data_file__is_pipe(session->file))

tools/perf/util/session.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -89,7 +89,7 @@ struct machine perf_session__findnew_machine(struct perf_session session, pid_
		}

		struct thread perf_session__findnew(struct perf_session session, pid_t pid);
		struct thread perf_session__register_idle_thread(struct perf_session session);
		int perf_session__register_idle_thread(struct perf_session *session);

		size_t perf_session__fprintf(struct perf_session session, FILE fp);

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