Wake up interruptible_select in remote_fileio ctrl-c handler

Message ID 1463668660-9205-1-git-send-email-yao.qi@linaro.org
State New, archived

Commit Message

Yao Qi May 19, 2016, 2:37 p.m. UTC
  As reported in PR 19998, after type ctrl-c, GDB hang there and does
not send interrupt.  It causes a fail in gdb.base/interrupt.exp.
All targets support remote fileio should be affected.

When we type ctrc-c, SIGINT is handled by remote_fileio_sig_set,
as shown below,

 #0  remote_fileio_sig_set (sigint_func=0x4495d0 <remote_fileio_ctrl_c_signal_handler(int)>) at /home/yao/SourceCode/gnu/gdb/git/gdb/remote-fileio.c:325
 #1  0x00000000004495de in remote_fileio_ctrl_c_signal_handler (signo=<optimised out>) at /home/yao/SourceCode/gnu/gdb/git/gdb/remote-fileio.c:349
 #2  <signal handler called>
 #3  0x00007ffff647ed83 in __select_nocancel () at ../sysdeps/unix/syscall-template.S:81
 #4  0x00000000005530ce in interruptible_select (n=10, readfds=readfds@entry=0x7fffffffd730, writefds=writefds@entry=0x0, exceptfds=exceptfds@entry=0x0,
    timeout=timeout@entry=0x0) at /home/yao/SourceCode/gnu/gdb/git/gdb/event-top.c:1017
 #5  0x000000000061ab20 in stdio_file_read (file=<optimised out>, buf=0x12d02e0 "\n\022-\001", length_buf=16383)
    at /home/yao/SourceCode/gnu/gdb/git/gdb/ui-file.c:577
 #6  0x000000000044a4dc in remote_fileio_func_read (buf=0x12c0360 "") at /home/yao/SourceCode/gnu/gdb/git/gdb/remote-fileio.c:583
 #7  0x0000000000449598 in do_remote_fileio_request (uiout=<optimised out>, buf_arg=buf_arg@entry=0x12c0340)
    at /home/yao/SourceCode/gnu/gdb/git/gdb/remote-fileio.c:1179

we don't set quit_serial_event,

      res = gdb_select (n, readfds, writefds, exceptfds, timeout);
  while (res == -1 && errno == EINTR);

  if (res == 1 && FD_ISSET (fd, readfds))
      errno = EINTR;
      return -1;
  return res;

we can't go out of the loop above, and that is why GDB can't send

Recently, we stop throwing exception from SIGINT handler
https://sourceware.org/ml/gdb-patches/2016-03/msg00372.html, which
is correct, because gdb_select is interruptible.  However, in the
same patch series, we add interruptible_select later as a wrapper
to gdb_select, https://sourceware.org/ml/gdb-patches/2016-03/msg00375.html
and it is not interruptible (because of the loop in it) unless
select/poll-able file descriptors are marked.

This fix in this patch is to call quit_serial_event_set, so that we can
go out of the loop above, return -1 and set errno to EINTR.

I don't have the test env to run testsuite against targets support
remote fileio.

2016-05-19  Yao Qi  <yao.qi@linaro.org>

	PR remote/19998
	* remote-fileio.c (remote_fileio_ctrl_c_signal_handler): Call
 gdb/remote-fileio.c | 2 ++
 1 file changed, 2 insertions(+)


Yao Qi June 1, 2016, 8:35 a.m. UTC | #1
Yao Qi <qiyaoltc@gmail.com> writes:

> 2016-05-19  Yao Qi  <yao.qi@linaro.org>
> 	PR remote/19998
> 	* remote-fileio.c (remote_fileio_ctrl_c_signal_handler): Call
> 	quit_serial_event_set.

I pushed it in.


diff --git a/gdb/remote-fileio.c b/gdb/remote-fileio.c
index 44817df..29c5ca3 100644
--- a/gdb/remote-fileio.c
+++ b/gdb/remote-fileio.c
@@ -348,6 +348,8 @@  remote_fileio_ctrl_c_signal_handler (int signo)
   remote_fileio_sig_set (remote_fileio_ctrl_c_signal_handler);
   remote_fio_ctrl_c_flag = 1;
+  /* Wake up interruptible_select.  */
+  quit_serial_event_set ();
 static void