Re: ttrace: Protocal error

[John David Anglin <dave@hiauly1.hia.nrc.ca>]

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On Sat, 09 Aug 2008, Pedro Alves wrote:

> If you were really in a TARGET_WAITKIND_SYSCALL_ENTRY, this would be
> at least the second resume after the lwp exit.
> Maybe I am reading the backtrace wrong though.  If you have the patience,
> showing what GDB outputs when you do a "run" after setting
> "set debug infrun 1" would help.

Attached.

Ignoring protocol errors seems to work.  Used the following.  Note
there is a conflict with your change.

Index: inf-ttrace.c
===================================================================
RCS file: /cvs/src/src/gdb/inf-ttrace.c,v
retrieving revision 1.30
diff -u -3 -p -r1.30 inf-ttrace.c
--- inf-ttrace.c	9 Jul 2008 22:23:05 -0000	1.30
+++ inf-ttrace.c	9 Aug 2008 18:35:51 -0000
@@ -787,12 +804,16 @@ inf_ttrace_kill (void)
 static int
 inf_ttrace_resume_callback (struct thread_info *info, void *arg)
 {
-  if (!ptid_equal (info->ptid, inferior_ptid))
+  /* There is a race condition in detecting when a thread is stopped.
+     So, we need to resume "dying" threads and ignore protocol errors
+     that occur from resuming threads that aren't stopped.  */
+  if (!ptid_equal (info->ptid, inferior_ptid) && !is_exited (info->ptid))
     {
       pid_t pid = ptid_get_pid (info->ptid);
       lwpid_t lwpid = ptid_get_lwp (info->ptid);
 
-      if (ttrace (TT_LWP_CONTINUE, pid, lwpid, TT_NOPC, 0, 0) == -1)
+      if (ttrace (TT_LWP_CONTINUE, pid, lwpid, TT_NOPC, 0, 0) == -1
+	  && errno != EPROTO)
 	perror_with_name (("ttrace"));
     }
 
Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)

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(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y

Starting program: /mnt/gnu/gcc/objdir/hppa2.0w-hp-hpux11.11/libgomp/testsuite/vla6.x3g 
infrun: wait_for_inferior (treat_exec_as_sigtrap=1)
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x91d0
infrun: quietly stopped
infrun: stop_stepping
infrun: resume (step=0, signal=0), stepping_over_breakpoint=0
infrun: wait_for_inferior (treat_exec_as_sigtrap=1)
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x19f8
infrun: quietly stopped
infrun: stop_stepping
warning: Private mapping of shared library text was not specified
by the executable; setting a breakpoint in a shared library which
is not privately mapped will not work.  See the HP-UX 11i v3 chatr
manpage for methods to privately map shared library text.
infrun: proceed (addr=0xffffffff, signal=0, step=0)
infrun: resume (step=0, signal=0), stepping_over_breakpoint=0
infrun: wait_for_inferior (treat_exec_as_sigtrap=0)
[New process 5170, lwp 7674424]
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_SPURIOUS
infrun: resume (step=0, signal=0), stepping_over_breakpoint=0
infrun: prepare_to_wait
[process 5170, lwp 7674424 exited]
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_SPURIOUS
infrun: resume (step=0, signal=0), stepping_over_breakpoint=0
0xc00268dc in ?? ()
ttrace: Protocol error.