[patch] Fix Linux attach to signalled/stopped processes
Pedro Alves
pedro@codesourcery.com
Fri Apr 11 22:21:00 GMT 2008
Some quick comments,
A Friday 11 April 2008 22:02:21, Daniel Jacobowitz wrote:
> + /* Pass on the last signal, if appropriate. */
> + if (lp->status == 0 && GET_LWP (lp->ptid) == GET_LWP (inferior_ptid)
> + && stop_signal != TARGET_SIGNAL_0 && signal_pass_state (stop_signal))
> + lp->status = W_STOPCODE (target_signal_to_host (stop_signal));
You're writing to lp->status of inferior_ptid, which isn't garantied
to be the main thread or the thread that got the last signal (user
may have used the "thread" command to switch threads, or we're stopped
at a breakpoint in some other thread not the main one, for example, or
the kernel decided to send the signal to some other thread because the
main one was already stopped?).
> /* We don't actually detach from the LWP that has an id equal to the
> overall process id just yet. */
> if (GET_LWP (lp->ptid) != GET_PID (lp->ptid))
>@@ -1263,14 +1343,29 @@ static void
> linux_nat_detach (char *args, int from_tty)
> {
> int pid;
>+ int status;
>+ enum target_signal sig;
>+
> if (target_can_async_p ())
> linux_nat_async (NULL, 0);
>
>- iterate_over_lwps (detach_callback, NULL);
>+ iterate_over_lwps (detach_callback, &status);
>
Passing &status seems bogus, since you're passing the status
in lp->status ?
> /* Only the initial process should be left right now. */
> gdb_assert (num_lwps == 1);
>
>+ /* Pass on any pending signal for the last LWP. */
>+ status = lwp_list->status;
>+ if (WIFSTOPPED (status) && (args == NULL || *args == '\0'))
>+ {
>+ args = alloca (8);
>+ sprintf (args, "%d", (int) WSTOPSIG (status));
>+ fprintf_unfiltered (gdb_stdlog,
>+ "LND: Sending signal %s to %s\n",
>+ args,
>+ target_pid_to_str (lwp_list->ptid));
>+ }
>+
>
I don't see where you're actually sending the signal. Even if you
did, it isn't guarantied you are passing this signal. It will miss it
if inferior_ptid isn't the main thread. See comments above.
Also, why the alloca dance instead of using
"Sending signal %d to %s\n" directly, if you're not doing anything
else with args? AKA, what's the plan for args?
What's supposed to happen if stop_signal was a SIGTRAP ?
--
Pedro Alves
More information about the Gdb-patches
mailing list