Commit-ID:  5e78c69b72276853ac64070a010e6df64723dba9
Gitweb:     http://git.kernel.org/tip/5e78c69b72276853ac64070a010e6df64723dba9
Author:     He Kuang <heku...@huawei.com>
AuthorDate: Fri, 10 Apr 2015 17:35:00 +0800
Committer:  Arnaldo Carvalho de Melo <a...@redhat.com>
CommitDate: Fri, 10 Apr 2015 10:13:59 -0300

perf buildid-list: Fix segfault when show DSOs with hits

commit: f3b623b8490a ("perf tools: Reference count struct thread")
appends every thread->node to dead_threads in machine__remove_thread()
and list_del_init() this node in thread__put().

perf_event__exit_del_thread() releases thread wihout using
machine__remove_thread(), and causes a NULL pointer crash when
list_del_init(&thread->node) is called. Fix this by using
machine_remove_thread() instead of using thread__put() directly.

This problem can be reproduced as following:

  $ perf record ls
  $ perf buildid-list --with-hits
  [ 3874.195070] perf[1018]: segfault at 0 ip 00000000004b0b15 sp
  00007ffc35b44780 error 6 in perf[400000+166000]
  Segmentation fault

After this patch:
  $ perf record ls
  $ perf buildid-list --with-hits
  bc23e7c3281e542650ba4324421d6acf78f4c23e /proc/kcore
  643324cb0e969f30c56d660f167f84a150845511 [vdso]
  0000000000000000000000000000000000000000 /bin/busybox
  ...

Signed-off-by: He Kuang <heku...@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Wang Nan <wangn...@huawei.com>
Link: 
http://lkml.kernel.org/r/1428658500-6483-1-git-send-email-heku...@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
 tools/perf/util/build-id.c | 8 ++------
 tools/perf/util/machine.c  | 4 +---
 tools/perf/util/machine.h  | 1 +
 3 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index f7fb258..61867df 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -59,12 +59,8 @@ static int perf_event__exit_del_thread(struct perf_tool 
*tool __maybe_unused,
        dump_printf("(%d:%d):(%d:%d)\n", event->fork.pid, event->fork.tid,
                    event->fork.ppid, event->fork.ptid);
 
-       if (thread) {
-               rb_erase(&thread->rb_node, &machine->threads);
-               if (machine->last_match == thread)
-                       thread__zput(machine->last_match);
-               thread__put(thread);
-       }
+       if (thread)
+               machine__remove_thread(machine, thread);
 
        return 0;
 }
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 9c380a2..527e032 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -14,8 +14,6 @@
 #include "unwind.h"
 #include "linux/hash.h"
 
-static void machine__remove_thread(struct machine *machine, struct thread *th);
-
 static void dsos__init(struct dsos *dsos)
 {
        INIT_LIST_HEAD(&dsos->head);
@@ -1256,7 +1254,7 @@ out_problem:
        return 0;
 }
 
-static void machine__remove_thread(struct machine *machine, struct thread *th)
+void machine__remove_thread(struct machine *machine, struct thread *th)
 {
        if (machine->last_match == th)
                thread__zput(machine->last_match);
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index e2faf3b..6d64ced 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -120,6 +120,7 @@ int machine__init(struct machine *machine, const char 
*root_dir, pid_t pid);
 void machine__exit(struct machine *machine);
 void machine__delete_threads(struct machine *machine);
 void machine__delete(struct machine *machine);
+void machine__remove_thread(struct machine *machine, struct thread *th);
 
 struct branch_info *sample__resolve_bstack(struct perf_sample *sample,
                                           struct addr_location *al);
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