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Re: Updated patch for Bug 13217 - thread apply all detach throws a SEGFAULT
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: ali_anwar <ali_anwar at codesourcery dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Thu, 27 Sep 2012 17:26:50 +0200
- Subject: Re: Updated patch for Bug 13217 - thread apply all detach throws a SEGFAULT
- References: <5062EA9B.1060505@codesourcery.com>
On Wed, 26 Sep 2012 13:44:27 +0200, ali_anwar wrote:
[...]
> --- gdb/thread.c 27 Jul 2012 00:52:36 -0000 1.149
> +++ gdb/thread.c 26 Sep 2012 09:51:13 -0000
> @@ -57,6 +57,7 @@
> struct thread_info *thread_list = NULL;
> static int highest_thread_num;
>
> +static int thread_valid (struct thread_info *);
Forward declaration not needed when all callers are after the function
definition like in this case.
> static void thread_command (char *tidstr, int from_tty);
> static void thread_apply_all_command (char *, int);
> static int thread_alive (struct thread_info *);
> @@ -73,6 +74,17 @@
> return tp;
> }
>
> +/* Return true if TP is valid thread. */
Empty line between a function comment tnd the function implementation.
Also the comment should end with two spaces:
/* Return true if TP is valid thread. */
> +static int
> +thread_valid (struct thread_info *tp)
> +{
> + struct thread_info *utp;
Two spaces, use one. Use empty line between declarations and code statements.
> + for (utp = thread_list; utp; utp = utp->next)
> + if (tp == utp)
> + return 1;
> + return 0;
> +}
> +
> void
> delete_step_resume_breakpoint (struct thread_info *tp)
> {
> @@ -1193,7 +1205,7 @@
> execute_command. */
> saved_cmd = xstrdup (cmd);
> make_cleanup (xfree, saved_cmd);
> - for (tp = thread_list; tp; tp = tp->next)
> + for (tp = thread_list; thread_valid(tp); tp = tp->next)
Space before function parameters:
thread_valid (tp)
> if (thread_alive (tp))
> {
> switch_to_thread (tp->ptid);
> @@ -1203,6 +1215,8 @@
> execute_command (cmd, from_tty);
> strcpy (cmd, saved_cmd); /* Restore exact command used
> previously. */
> + if (thread_count() == 0)
Space before function parameters:
thread_count ()
> + break;
This will not work universally. I did not try it but one can do something
like:
thread apply all call func()
Where func() will pthread_cancel some threads but not all of them. In such
case thread_count() will not be 0 but still tp->next may be invalid crashing
GDB.
You can remember 'num' and always try to find 'num + 1' thread or any higher
than 'num'.
Thanks,
Jan