Re: [PATCH] GDB checkpoint can't/shouldn't be possible with multiple threads on Linux

[Kevin Pouget <kevin.pouget@gmail.com>]

On Tue, Apr 12, 2011 at 9:41 AM, Pedro Alves <pedro@codesourcery.com> wrote:
> Small nit I should have caught before:
>
> On Tuesday 12 April 2011 14:27:49, Kevin Pouget wrote:
>> +static int
>> +inf_has_multiple_thread_cb (struct thread_info *tp, void *data)
>> +{
>> +  int *has_multiple_threads = (int *) data;
>
> can you rename this local as well, in line with the other
> local in the other function?  To "count", or "count_p", or something
> like that.  Thanks.  (pre-approved)

fixed with count_p, thanks


Kevin

--
2011-04-12 Kevin Pouget <kevin.pouget@st.com>

	PR threads/12628

	* linux-fork.c (checkpoint_command): Disallow checkpointing of
	processes with multiple threads.
	(inf_has_multiple_thread_cb): New function.
	(inf_has_multiple_threads): New function.
--

diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 7f654af..de512c3 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -616,6 +616,33 @@ linux_fork_checkpointing_p (int pid)
   return (checkpointing_pid == pid);
 }

+/* Callback for iterate over threads.  Used to check whether
+   the current inferior is multi-threaded.  Returns true as soon
+   as it sees the second thread of the current inferior.  */
+
+static int
+inf_has_multiple_thread_cb (struct thread_info *tp, void *data)
+{
+  int *count_p = (int *) data;
+
+  if (current_inferior ()->pid == ptid_get_pid (tp->ptid))
+    (*count_p)++;
+
+  /* Stop the iteration if multiple threads have been detected.  */
+  return *count_p > 1;
+}
+
+/* Return true if the current inferior is multi-threaded.  */
+
+static int
+inf_has_multiple_threads (void)
+{
+  int count = 0;
+
+  iterate_over_threads (inf_has_multiple_thread_cb, &count);
+  return (count > 1);
+}
+
 static void
 checkpoint_command (char *args, int from_tty)
 {
@@ -628,6 +655,14 @@ checkpoint_command (char *args, int from_tty)
   pid_t retpid;
   struct cleanup *old_chain;

+  if (!target_has_execution)
+    error (_("The program is not being run."));
+
+  /* Ensure that the inferior is not multithreaded.  */
+  update_thread_list ();
+  if (inf_has_multiple_threads ())
+    error (_("checkpoint: can't checkpoint multiple threads."));
+
   /* Make the inferior fork, record its (and gdb's) state.  */

   if (lookup_minimal_symbol ("fork", NULL, NULL) != NULL)