[commit+7.8] [patch+7.8?] Fix 'gcore' with exited threads

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Thu, 21 Aug 2014 13:32:57 +0200, Pedro Alves wrote:
> On 08/17/2014 10:16 PM, Jan Kratochvil wrote:
> > On Mon, 23 Jun 2014 17:06:37 +0200, Pedro Alves wrote:
> >> > What does the log show ?
> > gcore .../gdb/testsuite/gdb.threads/gcore-thread0.test^M
> > Cannot find new threads: debugger service failed^M
> > (gdb) FAIL: gdb.threads/gcore-thread.exp: save a zeroed-threads corefile
> > +
> > core .../gdb/testsuite/gdb.threads/gcore-thread0.test^M
> > ".../gdb/testsuite/gdb.threads/gcore-thread0.test" is not a core dump: File format not recognized^M
> > (gdb) FAIL: gdb.threads/gcore-thread.exp: core0file: re-load generated corefile (bad file format)
> 
> Thanks.  It'd be good to have this in the commit log.

I have put it to the commit log.
For the record as discussed in the past and not to repeat myself I just do not
agree with this statement.


> Otherwise OK.

Checked in: 22fd09ae995556cc1b898afe3d5901eb161d1102

> IMO, this is good for 7.8.

Checked in: 14adc931130880d75eccc023cbaec68790960235


Thanks,
Jan

commit 22fd09ae995556cc1b898afe3d5901eb161d1102
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Thu Aug 21 20:36:20 2014 +0200

    Fix 'gcore' with exited threads
    
    Program received signal SIGABRT, Aborted.
    [...]
    (gdb) gcore foobar
    Couldn't get registers: No such process.
    (gdb) info threads
    [...]
    (gdb) gcore foobar
    Saved corefile foobar
    (gdb)
    
    gcore tries to access the exited thread:
    [Thread 0x7ffff7fce700 (LWP 6895) exited]
    ptrace(PTRACE_GETREGS, 6895, 0, 0x7fff18167dd0) = -1 ESRCH (No such process)
    
    Without the TRY_CATCH protection testsuite FAILs for:
    	gcore .../gdb/testsuite/gdb.threads/gcore-thread0.test
    	Cannot find new threads: debugger service failed
    	(gdb) FAIL: gdb.threads/gcore-thread.exp: save a zeroed-threads corefile
    	+
    	core .../gdb/testsuite/gdb.threads/gcore-thread0.test
    	".../gdb/testsuite/gdb.threads/gcore-thread0.test" is not a core dump: File format not recognized
    	(gdb) FAIL: gdb.threads/gcore-thread.exp: core0file: re-load generated corefile (bad file format)
    Maybe the TRY_CATCH could be more inside update_thread_list().
    
    Similar update_thread_list() call is IMO missing in procfs_make_note_section()
    but I do not have where to verify that change.
    
    gdb/ChangeLog
    2014-08-21  Jan Kratochvil  <jan.kratochvil@redhat.com>
    
    	* linux-tdep.c (linux_corefile_thread_callback): Ignore THREAD_EXITED.
    	(linux_make_corefile_notes): call update_thread_list, protected against
    	exceptions.
    
    gdb/testsuite/ChangeLog
    2014-08-21  Jan Kratochvil  <jan.kratochvil@redhat.com>
    
    	* gdb.threads/gcore-stale-thread.c: New file.
    	* gdb.threads/gcore-stale-thread.exp: New file.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index bf7f618..e8f652f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2014-08-21  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* linux-tdep.c (linux_corefile_thread_callback): Ignore THREAD_EXITED.
+	(linux_make_corefile_notes): call update_thread_list, protected against
+	exceptions.
+
 2014-08-21  Pedro Alves  <palves@redhat.com>
 
 	* infcmd.c (attach_command): Remove comment.
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index d0f1106..dae59c5 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -1194,6 +1194,11 @@ linux_corefile_thread_callback (struct thread_info *info, void *data)
 {
   struct linux_corefile_thread_data *args = data;
 
+  /* It can be current thread
+     which cannot be removed by update_thread_list.  */
+  if (info->state == THREAD_EXITED)
+    return 0;
+
   if (ptid_get_pid (info->ptid) == args->pid)
     {
       struct cleanup *old_chain;
@@ -1445,6 +1450,7 @@ linux_make_corefile_notes (struct gdbarch *gdbarch, bfd *obfd, int *note_size,
   char *note_data = NULL;
   gdb_byte *auxv;
   int auxv_len;
+  volatile struct gdb_exception e;
 
   if (linux_fill_prpsinfo (&prpsinfo))
     {
@@ -1468,6 +1474,12 @@ linux_make_corefile_notes (struct gdbarch *gdbarch, bfd *obfd, int *note_size,
     }
 
   /* Thread register information.  */
+  TRY_CATCH (e, RETURN_MASK_ERROR)
+    {
+      update_thread_list ();
+    }
+  if (e.reason < 0)
+    exception_print (gdb_stderr, e);
   thread_args.gdbarch = gdbarch;
   thread_args.pid = ptid_get_pid (inferior_ptid);
   thread_args.obfd = obfd;
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 31c64ff..8689b5e 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-08-21  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.threads/gcore-stale-thread.c: New file.
+	* gdb.threads/gcore-stale-thread.exp: New file.
+
 2014-08-21  Pedro Alves  <palves@redhat.com>
 
 	* gdb.base/gcore-buffer-overflow.exp: Remove "help gcore" test.
diff --git a/gdb/testsuite/gdb.threads/gcore-stale-thread.c b/gdb/testsuite/gdb.threads/gcore-stale-thread.c
new file mode 100644
index 0000000..944acba
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/gcore-stale-thread.c
@@ -0,0 +1,48 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2014 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <pthread.h>
+#include <assert.h>
+
+static pthread_t main_thread;
+
+static void *
+start (void *arg)
+{
+  int i;
+
+  i = pthread_join (main_thread, NULL);
+  assert (i == 0);
+
+  return arg; /* break-here */
+}
+
+int
+main (void)
+{
+  pthread_t thread;
+  int i;
+
+  main_thread = pthread_self ();
+
+  i = pthread_create (&thread, NULL, start, NULL);
+  assert (i == 0);
+
+  pthread_exit (NULL);
+  assert (0);
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.threads/gcore-stale-thread.exp b/gdb/testsuite/gdb.threads/gcore-stale-thread.exp
new file mode 100644
index 0000000..291c56f
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/gcore-stale-thread.exp
@@ -0,0 +1,57 @@
+# Copyright 2014 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+standard_testfile
+set corefile [standard_output_file ${testfile}.core]
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable debug] != ""} {
+    return -1
+}
+
+clean_restart ${testfile}
+
+gdb_test_no_output "set non-stop on"
+
+if { ! [ runto_main ] } then {
+    return -1
+}
+
+gdb_test_multiple "info threads" "threads are supported" {
+    -re ".* main .*\r\n$gdb_prompt $" {
+	# OK, threads are supported.
+    }
+    -re "\r\n$gdb_prompt $" {
+	unsupported "gdb does not support threads on this target"
+	return -1
+    }
+}
+
+gdb_breakpoint ${srcfile}:[gdb_get_line_number "break-here"]
+# gdb_continue_to_breakpoint does not work as it uses "$gdb_prompt $" regex
+# which does not work due to the output: (gdb) [Thread ... exited]
+set name "continue to breakpoint: break-here"
+gdb_test_multiple "continue" $name {
+    -re "Breakpoint .* (at|in) .* break-here .*\r\n$gdb_prompt " {
+	pass $name
+    }
+}
+
+gdb_gcore_cmd "$corefile" "save a corefile"
+
+# Do not run "info threads" before "gcore" as it could workaround the bug
+# by discarding non-current exited threads.
+gdb_test "info threads" \
+         {The current thread <Thread ID 1> has terminated\.  See `help thread'\.} \
+	 "exited thread is current due to non-stop"