diff mbox

Fix 'gcore' with exited threads

Message ID 20140609203020.GA22447@host2.jankratochvil.net
State Under Review
Headers show

Commit Message

Jan Kratochvil June 9, 2014, 8:30 p.m. UTC
Hi,

https://bugzilla.redhat.com/show_bug.cgi?id=1099405

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:
	FAIL: gdb.threads/gcore-thread.exp: save a zeroed-threads corefile
	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.


Jan
gdb/
2014-06-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* linux-tdep.c (linux_make_corefile_notes): call update_thread_list,
	protected against exceptions.

gdb/testsuite/
2014-06-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.threads/gcore-stale-thread.c: New file.
	* gdb.threads/gcore-stale-thread.exp: New file.

Comments

Pedro Alves June 23, 2014, 3:06 p.m. UTC | #1
On 06/09/2014 09:30 PM, Jan Kratochvil wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1099405
>
> 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)

Note this will still happen if you have the exited thread selected,
as in that case the thread can't be deleted:

$ ./gdb ~/gdb/tests/threads -ex "set non-stop on"
...
(gdb) t 2
[Switching to thread 2 (Thread 0x7ffff7fc6700 (LWP 23009))]
#0  thread_function0 (arg=0x0) at threads.c:64
64              usleep (1);  /* Loop increment.  */
(gdb) p *myp=0
$1 = 0
(gdb) c&
Continuing.
(gdb) [Thread 0x7ffff7fc6700 (LWP 23009) exited]
(gdb) thread
[Current thread is 2 (Thread 0x7ffff7fc6700 (LWP 22973)) (exited)]
(gdb) info threads
  Id   Target Id         Frame
  3    Thread 0x7ffff77c5700 (LWP 22974) "threads" (running)
  1    Thread 0x7ffff7fc7740 (LWP 22972) "threads" (running)

The current thread <Thread ID 2> has terminated.  See `help thread'.
(gdb) gcore
Couldn't get registers: No such process.
(gdb)

It seems to me linux_corefile_thread_callback should skip exited
threads too.

> Without the TRY_CATCH protection testsuite FAILs for:
> 	FAIL: gdb.threads/gcore-thread.exp: save a zeroed-threads corefile
> 	FAIL: gdb.threads/gcore-thread.exp: core0file: re-load generated corefile (bad file format)

What does the log show ?

> Maybe the TRY_CATCH could be more inside update_thread_list().

I'll assume "info threads" is failing at that point too
then.  Maybe we should downgrade whatever error is triggering
to a warning?

> Similar update_thread_list() call is IMO missing in procfs_make_note_section()
> but I do not have where to verify that change.

I wonder whether we should update the thread list in generic
code (write_gcore_file).

> +gdb_test_multiple "help gcore" "help gcore" {
> +    -re "Undefined command: .gcore.*\r\n$gdb_prompt $" {

Is this coming from copy/paste of existing tests?  I believe
this is is stale -- gcore.o has been in COMMON_OBS for a while
now.  I think the actual error will be whatever the default for
the target method throws.

> +	# gcore command not supported -- nothing to test here.
> +	unsupported "gdb does not support gcore on this target"
> +	return -1
> +    }
> +    -re "Save a core file .*\r\n$gdb_prompt $" {
> +	pass "help gcore"
> +    }
> +}
diff mbox

Patch

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index c10b8ee..fc5a943 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -1440,6 +1440,7 @@  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))
     {
@@ -1463,6 +1464,12 @@  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/gdb.threads/gcore-stale-thread.c b/gdb/testsuite/gdb.threads/gcore-stale-thread.c
new file mode 100644
index 0000000..9fba7a7
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/gcore-stale-thread.c
@@ -0,0 +1,39 @@ 
+/* 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 void *
+start (void *arg)
+{
+  return arg;
+}
+
+int
+main (void)
+{
+  pthread_t thread;
+  int i;
+
+  i = pthread_create (&thread, NULL, start, NULL);
+  assert (i == 0);
+  i = pthread_join (thread, NULL);
+  assert (i == 0);
+
+  return 0; /* break-here */
+}
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..a6677a8
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/gcore-stale-thread.exp
@@ -0,0 +1,56 @@ 
+# 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/>.
+
+# This file was written by Michael Snyder (msnyder@redhat.com)
+# This is a test for the gdb command "generate-core-file".
+
+standard_testfile
+set corefile [standard_output_file ${testfile}.core]
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable debug] != ""} {
+    return -1
+}
+
+clean_restart ${testfile}
+
+gdb_test_multiple "help gcore" "help gcore" {
+    -re "Undefined command: .gcore.*\r\n$gdb_prompt $" {
+	# gcore command not supported -- nothing to test here.
+	unsupported "gdb does not support gcore on this target"
+	return -1
+    }
+    -re "Save a core file .*\r\n$gdb_prompt $" {
+	pass "help gcore"
+    }
+}
+
+if { ! [ runto_main ] } then {
+    return -1
+}
+
+gdb_test_multiple "info threads" "threads are supported" {
+    -re ".* main .*\r\n$gdb_prompt $" {
+	# OK, threads are supported.
+    }
+    -re "\r\n$gdb_prompt $" {
+	unsupported "gdb does not support threads on this target"
+	return -1
+    }
+}
+
+gdb_breakpoint ${srcfile}:[gdb_get_line_number "break-here"]
+gdb_continue_to_breakpoint "break-here" ".* break-here .*"
+
+gdb_gcore_cmd "$corefile" "save a corefile"