There is a program on remote-debugging a multi-threaded program which
uses signals.  After receiving a signal (configured to "nostop"), the
thread which receives it resumes normally but other threads leave
stopped.

I'm using gdb/snapshots/branch/gdb-6.0.90.tar.bz2 (Mar 1) on i386-linux.

The test program to reproduce this problem is attached (sigtest.c).
It creates a thread which waits SIGUSR1 and main thread sends SIGUSR1
to the thread every 10 secs.  Usual output is:

$ ./sigtest
[sigtest:26616:1024]:main
[sigtest:26618:1026]:func
[sigtest:26616:1024]:send SIGUSR1
[sigtest:26618:1026]:sigwait 10
[sigtest:26616:1024]:send SIGUSR1
[sigtest:26618:1026]:sigwait 10
...


gdb debug session log is:

(gdb) target remote localhost:50000
Remote debugging using localhost:50000
0x080480e0 in _start ()
(gdb) handle SIGUSR1 nostop
Signal        Stop      Print   Pass to program Description
SIGUSR1       No        Yes     Yes             User defined signal 1
(gdb) c
Continuing.
[New Thread 1024]
[New Thread 1026]


and gdbserver side log is:

$ ./gdbserver host:50000 ./sigtest
Process ./sigtest created; pid = 26599
Listening on port 50000
Remote debugging from host 127.0.0.1
[sigtest:26599:1024]:main
[sigtest:26601:1026]:func
[sigtest:26599:1024]:send SIGUSR1
[sigtest:26601:1026]:sigwait 10
(no more output)


ps output is:

$ ps a
  PID TTY      STAT   TIME COMMAND
26598 pts/4    S      0:00 ./gdbserver host:50000 ./sigtest
26599 pts/4    T      0:00 ./sigtest
26600 pts/4    T      0:00 ./sigtest
26601 pts/4    S      0:00 ./sigtest

PID 26601 is a thread which receives SIGUSR1.  This was resumed but
others are still stopped.


I tried "set remote verbose-resume-packet off" and got same results.

It seems gdbserver does not handle 'continue with signal' case
correctly.  I tried to fix this problem and create a patch below, and
it seems work, but I'm not sure this is a correct fix (or correct
place).

diff -up gdb-6.0.90.org/gdb/gdbserver/server.c gdb-6.0.90/gdb/gdbserver/server.c
--- gdb-6.0.90.org/gdb/gdbserver/server.c	Mon Mar  1 01:49:38 2004
+++ gdb-6.0.90/gdb/gdbserver/server.c	Wed Mar  3 23:49:42 2004
@@ -235,6 +235,8 @@ handle_v_cont (char *own_buf, char *stat
     cont_thread = resume_info[0].thread;
   else
     cont_thread = -1;
+  if (cont_thread != -1 && n == 1 && !resume_info[0].step)
+    resume_info[i].leave_stopped = 0; /* signal the thread and run others */
   set_desired_inferior (0);
 
   (*the_target->resume) (resume_info);
@@ -292,7 +294,7 @@ myresume (int step, int sig)
   resume_info[n].thread = -1;
   resume_info[n].step = 0;
   resume_info[n].sig = 0;
-  resume_info[n].leave_stopped = (cont_thread > 0);
+  resume_info[n].leave_stopped = step && (cont_thread > 0);
 
   (*the_target->resume) (resume_info);
 }


Other attached files are some session logs for gdb (set debug remote
1) and gdbserver (debug_thread = 1).

gdb.output1 and gdbserver.output1 are logs with "verbose-resume on".
gdb.output2 and gdbserver.output2 are logs with "verbose-resume off".

---
Atsushi Nemoto