From a25d8bf9c5b2c9d3671f4508c9132485c65c3773 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 24 Mar 2015 21:01:29 +0000 Subject: [PATCH] Fix "thread apply all" with exited threads I noticed that "thread apply all" sometimes crashes. The problem is that thread_apply_all_command doesn take exited threads into account, and we qsort and then walk more elements than there really ever were put in the array. Valgrind shows: The current thread has terminated. See `help thread'. (gdb) thread apply all p 1 Thread 1 (Thread 0x7ffff7fc2740 (LWP 29579)): $1 = 1 ==29576== Use of uninitialised value of size 8 ==29576== at 0x639CA8: set_thread_refcount (thread.c:1337) ==29576== by 0x5C2C7B: do_my_cleanups (cleanups.c:155) ==29576== by 0x5C2CE8: do_cleanups (cleanups.c:177) ==29576== by 0x63A191: thread_apply_all_command (thread.c:1477) ==29576== by 0x50374D: do_cfunc (cli-decode.c:105) ==29576== by 0x506865: cmd_func (cli-decode.c:1893) ==29576== by 0x7562CB: execute_command (top.c:476) ==29576== by 0x647DA4: command_handler (event-top.c:494) ==29576== by 0x648367: command_line_handler (event-top.c:692) ==29576== by 0x7BF7C9: rl_callback_read_char (callback.c:220) ==29576== by 0x64784C: rl_callback_read_char_wrapper (event-top.c:171) ==29576== by 0x647CB5: stdin_event_handler (event-top.c:432) ==29576== ... This can happen easily today as linux-nat.c/linux-thread-db.c are forgetting to purge non-current exited threads. But even with that fixed, we can always do "thread apply all" with an exited thread selected, which won't be deleted until the user switches to another thread. That's what the test added by this commit exercises. Tested on x86_64 Fedora 20. gdb/ChangeLog: 2015-03-24 Pedro Alves * thread.c (thread_apply_all_command): Take exited threads into account. gdb/testsuite/ChangeLog: 2015-03-24 Pedro Alves * gdb.threads/no-unwaited-for-left.exp: Test "thread apply all". --- gdb/ChangeLog | 5 +++++ gdb/testsuite/ChangeLog | 4 ++++ .../gdb.threads/no-unwaited-for-left.exp | 4 ++++ gdb/thread.c | 15 ++++++++++----- 4 files changed, 23 insertions(+), 5 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 2cd79a5242e..a5abe28e14d 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2015-03-24 Pedro Alves + + * thread.c (thread_apply_all_command): Take exited threads into + account. + 2015-03-24 Pedro Alves * infrun.c (resume, proceed): Mention diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 824d6fc54bb..9d9c086446d 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2015-03-24 Pedro Alves + + * gdb.threads/no-unwaited-for-left.exp: Test "thread apply all". + 2015-03-24 Pedro Alves * gdb.threads/schedlock.exp (test_step): No longer expect that diff --git a/gdb/testsuite/gdb.threads/no-unwaited-for-left.exp b/gdb/testsuite/gdb.threads/no-unwaited-for-left.exp index 3bb333689ad..518301e7bcc 100644 --- a/gdb/testsuite/gdb.threads/no-unwaited-for-left.exp +++ b/gdb/testsuite/gdb.threads/no-unwaited-for-left.exp @@ -65,3 +65,7 @@ gdb_test "continue" \ gdb_test "info threads" \ "\r\n\[ \t\]*Id\[ \t\]+Target\[ \t\]+Id\[ \t\]+Frame\[ \t\]*\r\n *3 *Thread \[^\r\n\]* \[^\r\n\]*.*The current thread has terminated.*" \ "only thread 3 left, main thread terminated" + +# Make sure thread apply all works when we have exited threads in the +# list. +gdb_test "thread apply all print 999" " = 999" "thread apply all with exited thread" diff --git a/gdb/thread.c b/gdb/thread.c index 01eb2ba94f4..ec398f578d2 100644 --- a/gdb/thread.c +++ b/gdb/thread.c @@ -1434,9 +1434,10 @@ thread_apply_all_command (char *cmd, int from_tty) execute_command. */ saved_cmd = xstrdup (cmd); make_cleanup (xfree, saved_cmd); - tc = thread_count (); - if (tc) + /* Note this includes exited threads. */ + tc = thread_count (); + if (tc != 0) { struct thread_info **tp_array; struct thread_info *tp; @@ -1446,8 +1447,6 @@ thread_apply_all_command (char *cmd, int from_tty) command. */ tp_array = xmalloc (sizeof (struct thread_info *) * tc); make_cleanup (xfree, tp_array); - ta_cleanup.tp_array = tp_array; - ta_cleanup.count = tc; ALL_NON_EXITED_THREADS (tp) { @@ -1455,9 +1454,15 @@ thread_apply_all_command (char *cmd, int from_tty) tp->refcount++; i++; } + /* Because we skipped exited threads, we may end up with fewer + threads in the array than the total count of threads. */ + gdb_assert (i <= tc); - qsort (tp_array, i, sizeof (*tp_array), tp_array_compar); + if (i != 0) + qsort (tp_array, i, sizeof (*tp_array), tp_array_compar); + ta_cleanup.tp_array = tp_array; + ta_cleanup.count = i; make_cleanup (set_thread_refcount, &ta_cleanup); for (k = 0; k != i; k++) -- 2.30.2