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

Kevin Pouget
2011-08-31T12:45:28Z

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On Tue, Apr 12, 2011 at 3:54 PM, Kevin Pouget <kevin.pouget@gmail.com> wrote:
>
> 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

Hello,

my copyright assignment is now ready, so I regenerated the patch
against the up-to-date trunk

Cordially,

Kevin

--

2011-08-31 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.

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From aaf0bedfe6aa61ba06761dbe381770ba86bddf6a Mon Sep 17 00:00:00 2001
From: Kevin Pouget <kevin.pouget@st.com>
Date: Tue, 12 Apr 2011 10:31:40 -0400
Subject: [PATCH] Disallow checkpointing of multiple threads

Signed-off-by: Kevin Pouget <kevin.pouget@st.com>
---
gdb/linux-fork.c | 35 +++++++++++++++++++++++++++++++++++
1 files changed, 35 insertions(+), 0 deletions(-)

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)
--
1.7.6