Change SIGINT handler for extension languages only when target terminal is ours

I see a timeout in gdb.base/random-signal.exp,

 Continuing.^M
 PASS: gdb.base/random-signal.exp: continue
 ^CPython Exception <type 'exceptions.KeyboardInterrupt'> <type
 exceptions.KeyboardInterrupt'>: ^M
 FAIL: gdb.base/random-signal.exp: stop with control-c (timeout)

it can be reproduced by running random-signal.exp with native-gdbserver
in a loop, like this, and the fail will be shown in about 20 runs,

$ (set -e; while true; do make check RUNTESTFLAGS="--target_board=native-gdbserver random-signal.exp"; done)

In the test, the program is being single-stepped for software watchpoint,
and in each internal stop, python unwinder sniffer is used,

 #0  pyuw_sniffer (self=<optimised out>, this_frame=<optimised out>, cache_ptr=0xd554f8) at /home/yao/SourceCode/gnu/gdb/git/gdb/python/py-unwind.c:608
 #1  0x00000000006a10ae in frame_unwind_try_unwinder (this_frame=this_frame@entry=0xd554e0, this_cache=this_cache@entry=0xd554f8, unwinder=0xecd540)
     at /home/yao/SourceCode/gnu/gdb/git/gdb/frame-unwind.c:107
 #2  0x00000000006a143f in frame_unwind_find_by_frame (this_frame=this_frame@entry=0xd554e0, this_cache=this_cache@entry=0xd554f8)
     at /home/yao/SourceCode/gnu/gdb/git/gdb/frame-unwind.c:163
 #3  0x000000000069dc6b in compute_frame_id (fi=0xd554e0) at /home/yao/SourceCode/gnu/gdb/git/gdb/frame.c:454
 #4  get_prev_frame_if_no_cycle (this_frame=this_frame@entry=0xd55410) at /home/yao/SourceCode/gnu/gdb/git/gdb/frame.c:1781
 #5  0x000000000069fdb9 in get_prev_frame_always_1 (this_frame=0xd55410) at /home/yao/SourceCode/gnu/gdb/git/gdb/frame.c:1955
 #6  get_prev_frame_always (this_frame=this_frame@entry=0xd55410) at /home/yao/SourceCode/gnu/gdb/git/gdb/frame.c:1971
 #7  0x00000000006a04b1 in get_prev_frame (this_frame=this_frame@entry=0xd55410) at /home/yao/SourceCode/gnu/gdb/git/gdb/frame.c:2213

when GDB goes to python extension, or other language extension, the
SIGINT handler is changed, and is restored when GDB leaves extension
language.  GDB only stays in extension language for a very short period
in this case, but if ctrl-c is pressed at that moment, python extension
will handle the SIGINT, and exceptions.KeyboardInterrupt is shown.

Language extension is used in GDB side rather than inferior side,
so GDB should only change SIGINT handler for extension language when
the terminal is ours (not inferior's).  This is what this patch does.
With this patch applied, I run random-signal.exp in a loop for 18
hours, and no fail is shown.

gdb:

2016-01-08  Yao Qi  <yao.qi@linaro.org>

	* extension.c: Include target.h.
	(set_active_ext_lang): Only call install_gdb_sigint_handler,
	check_quit_flag, and set_quit_flag if target_terminal_is_ours
	returns false.
	(restore_active_ext_lang): Likewise.
	* target.c (target_terminal_is_ours): New function.
	* target.h (target_terminal_is_ours): Declare.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 73ba8cd3aa243e0000646ea621b8db3052c41419..471d02bca8c6533d2357fe78966489f654922ace 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2016-01-08  Yao Qi  <yao.qi@linaro.org>
+
+       * extension.c: Include target.h.
+       (set_active_ext_lang): Only call install_gdb_sigint_handler,
+       check_quit_flag, and set_quit_flag if target_terminal_is_ours
+       returns false.
+       (restore_active_ext_lang): Likewise.
+       * target.c (target_terminal_is_ours): New function.
+       * target.h (target_terminal_is_ours): Declare.
+
 2016-01-07  Maciej W. Rozycki  <macro@imgtec.com>
 
        * mips-tdep.c (mips_breakpoint_from_pc): Rename local `status'

diff --git a/gdb/extension.c b/gdb/extension.c
index 5c23bcc698f7f3d4a2855103f938a6fb402f2fa7..d2c5669e0eda5f0cae68607aa937a8a918e53c80 100644 (file)
--- a/gdb/extension.c
+++ b/gdb/extension.c
@@ -22,6 +22,7 @@
 
 #include "defs.h"
 #include <signal.h>
+#include "target.h"
 #include "auto-load.h"
 #include "breakpoint.h"
 #include "event-top.h"
@@ -746,19 +747,24 @@ set_active_ext_lang (const struct extension_language_defn *now_active)
     = XCNEW (struct active_ext_lang_state);
 
   previous->ext_lang = active_ext_lang;
+  previous->sigint_handler.handler_saved = 0;
   active_ext_lang = now_active;
 
-  /* If the newly active extension language uses cooperative SIGINT handling
-     then ensure GDB's SIGINT handler is installed.  */
-  if (now_active->language == EXT_LANG_GDB
-      || now_active->ops->check_quit_flag != NULL)
-    install_gdb_sigint_handler (&previous->sigint_handler);
-
-  /* If there's a SIGINT recorded in the cooperative extension languages,
-     move it to the new language, or save it in GDB's global flag if the newly
-     active extension language doesn't use cooperative SIGINT handling.  */
-  if (check_quit_flag ())
-    set_quit_flag ();
+  if (target_terminal_is_ours ())
+    {
+      /* If the newly active extension language uses cooperative SIGINT
+        handling then ensure GDB's SIGINT handler is installed.  */
+      if (now_active->language == EXT_LANG_GDB
+         || now_active->ops->check_quit_flag != NULL)
+       install_gdb_sigint_handler (&previous->sigint_handler);
+
+      /* If there's a SIGINT recorded in the cooperative extension languages,
+        move it to the new language, or save it in GDB's global flag if the
+        newly active extension language doesn't use cooperative SIGINT
+        handling.  */
+      if (check_quit_flag ())
+       set_quit_flag ();
+    }
 
   return previous;
 }
@@ -772,16 +778,19 @@ restore_active_ext_lang (struct active_ext_lang_state *previous)
 
   active_ext_lang = previous->ext_lang;
 
-  /* Restore the previous SIGINT handler if one was saved.  */
-  if (previous->sigint_handler.handler_saved)
-    install_sigint_handler (&previous->sigint_handler);
-
-  /* If there's a SIGINT recorded in the cooperative extension languages,
-     move it to the new language, or save it in GDB's global flag if the newly
-     active extension language doesn't use cooperative SIGINT handling.  */
-  if (check_quit_flag ())
-    set_quit_flag ();
-
+  if (target_terminal_is_ours ())
+    {
+      /* Restore the previous SIGINT handler if one was saved.  */
+      if (previous->sigint_handler.handler_saved)
+       install_sigint_handler (&previous->sigint_handler);
+
+      /* If there's a SIGINT recorded in the cooperative extension languages,
+        move it to the new language, or save it in GDB's global flag if the
+        newly active extension language doesn't use cooperative SIGINT
+        handling.  */
+      if (check_quit_flag ())
+       set_quit_flag ();
+    }
   xfree (previous);
 }
 

diff --git a/gdb/target.c b/gdb/target.c
index d331fe4204479effd9a219c9524473522a7156e3..e88d60c506c2dce7bf3f8a2d628d3a2d830950d0 100644 (file)
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -466,6 +466,14 @@ target_terminal_is_inferior (void)
 
 /* See target.h.  */
 
+int
+target_terminal_is_ours (void)
+{
+  return (terminal_state == terminal_is_ours);
+}
+
+/* See target.h.  */
+
 void
 target_terminal_inferior (void)
 {

diff --git a/gdb/target.h b/gdb/target.h
index dd2896f5a501a7b2e79fd16897cc90702cca0b6f..e1419a94e55b732b93c5e0b53d2c303681561092 100644 (file)
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1503,6 +1503,10 @@ extern int target_remove_breakpoint (struct gdbarch *gdbarch,
 
 extern int target_terminal_is_inferior (void);
 
+/* Returns true if our terminal settings are in effect.  */
+
+extern int target_terminal_is_ours (void);
+
 /* Initialize the terminal settings we record for the inferior,
    before we actually run the inferior.  */