[binutils-gdb] gdbserver/Linux: unbreak non-stop

[Pedro Alves <palves at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=91baf43fa70827325272667c8e7a86c553c767dc

commit 91baf43fa70827325272667c8e7a86c553c767dc
Author: Pedro Alves <palves@redhat.com>
Date:   Thu Mar 19 16:51:09 2015 +0000

    gdbserver/Linux: unbreak non-stop
    
    The previous change added an assertion that is catching yet another
    bug in count_events_callback/select_event_lwp_callback:
    
      (gdb)
      PASS: gdb.mi/mi-nonstop.exp: interrupted
      mi_expect_interrupt: expecting: \*stopped,(reason="signal-received",signal-name="0",signal-meaning="Signal 0"|reason="signal-received",signal-name="SIGINT",signal-meaning="Interrupt")[^
      ]*
    
      /home/pedro/gdb/mygit/src/gdb/gdbserver/linux-low.c:2329: A problem internal to GDBserver has been detected.
      select_event_lwp: Assertion `num_events > 0' failed.
      =thread-group-exited,id="i1"
    
    Certainly select_event_lwp_callback should always at least find one
    event, as it's only called because an event triggered (though we may
    have more than one: the point of the function is randomly picking
    one).
    
    An LWP that GDB previously asked to continue/step (thus is resumed)
    and gets a vCont;t request ends up with last_resume_kind ==
    resume_stop.  These functions in gdbserver used to filter out events
    that weren't going to be reported to GDB; I think the last_resume_kind
    kind check used to make sense at that point, but it no longer does.
    
    gdb/gdbserver/ChangeLog:
    2015-03-19  Pedro Alves  <palves@redhat.com>
    
    	* linux-low.c (count_events_callback, select_event_lwp_callback):
    	No longer check whether the thread has resume_stop as last resume
    	kind.

Diff:
---
 gdb/gdbserver/ChangeLog   | 6 ++++++
 gdb/gdbserver/linux-low.c | 4 +---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index df8f9ab..0383e67 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,9 @@
+2015-03-19  Pedro Alves  <palves@redhat.com>
+
+	* linux-low.c (count_events_callback, select_event_lwp_callback):
+	No longer check whether the thread has resume_stop as last resume
+	kind.
+
 2015-03-19 Pedro Alves  <palves@redhat.com>
 
 	* linux-low.c (count_events_callback, select_event_lwp_callback):
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index e53e0fc..2b988ec 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -2245,7 +2245,6 @@ count_events_callback (struct inferior_list_entry *entry, void *data)
 
   /* Count only resumed LWPs that have an event pending. */
   if (thread->last_status.kind == TARGET_WAITKIND_IGNORE
-      && thread->last_resume_kind != resume_stop
       && lp->status_pending_p)
     (*count)++;
 
@@ -2280,8 +2279,7 @@ select_event_lwp_callback (struct inferior_list_entry *entry, void *data)
   gdb_assert (selector != NULL);
 
   /* Select only resumed LWPs that have an event pending. */
-  if (thread->last_resume_kind != resume_stop
-      && thread->last_status.kind == TARGET_WAITKIND_IGNORE
+  if (thread->last_status.kind == TARGET_WAITKIND_IGNORE
       && lp->status_pending_p)
     if ((*selector)-- == 0)
       return 1;