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[binutils-gdb] Initialize last_resume_kind for remote fork child


https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=bfacd19d64c76b740a4a9c18dce4277e4a9afde5

commit bfacd19d64c76b740a4a9c18dce4277e4a9afde5
Author: Don Breazeal <donb@codesourcery.com>
Date:   Thu May 28 13:12:01 2015 -0700

    Initialize last_resume_kind for remote fork child
    
    This patch fixes some intermittent test failures in
    gdb.base/foll-vfork.exp where a vfork child would be (incorrectly)
    resumed when handling the vfork event.  In this case the result
    was a subsequent event reported to the client side as a SIGTRAP
    delivered to the as-yet-unknown child thread.
    
    The new thread was resumed (incorrectly) in linux-low.c when
    resume_stopped_resumed_lwps was called from
    linux_wait_for_event_filtered after the vfork event had been
    handled in handle_extended_wait.
    
    Gdbserver/linux-low.c's add_thread function creates threads with
    last_resume_kind == resume_continue by default.  This field is
    used by resume_stopped_resumed_lwps to decide whether to perform
    the resume:
    
    static void
    resume_stopped_resumed_lwps (struct inferior_list_entry *entry) {
      struct thread_info *thread = (struct thread_info *) entry;
      struct lwp_info *lp = get_thread_lwp (thread);
    
      if (lp->stopped
          && !lp->status_pending_p
          && thread->last_resume_kind != resume_stop
          && thread->last_status.kind == TARGET_WAITKIND_IGNORE)
        {
    
    So the fix is to make sure to set thread->last_resume_kind to
    resume_stop.  Here we do that for new fork children in
    gdbserver/linux-low.c:handle_extended_wait.
    
    In addition, it seemed prudent to initialize lwp_info.status_pending_p
    for the new fork child.  I also rearranged the initialization code
    so that all of the lwp_info initialization was together, rather than
    intermixed with thread_info and process_info initialization.
    
    Tested native, native-gdbserver, native-extended-gdbserver on
    x86_64 GNU/Linux.
    
    gdb/gdbserver/
    
    	* linux-low.c (handle_extended_wait): Initialize
    	thread_info.last_resume_kind for new fork children.

Diff:
---
 gdb/gdbserver/ChangeLog   | 5 +++++
 gdb/gdbserver/linux-low.c | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 0f30c66..4e4f429 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2015-05-28  Don Breazeal  <donb@codesourcery.com>
+
+	* linux-low.c (handle_extended_wait): Initialize
+	thread_info.last_resume_kind for new fork children.
+
 2015-05-15  Pedro Alves  <palves@redhat.com>
 
 	* target.h (target_handle_new_gdb_connection): Rewrite using if
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 9f3ea48..d763c66 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -457,6 +457,7 @@ handle_extended_wait (struct lwp_info *event_lwp, int wstat)
 	  struct process_info *parent_proc;
 	  struct process_info *child_proc;
 	  struct lwp_info *child_lwp;
+	  struct thread_info *child_thr;
 	  struct target_desc *tdesc;
 
 	  ptid = ptid_build (new_pid, new_pid, 0);
@@ -479,6 +480,10 @@ handle_extended_wait (struct lwp_info *event_lwp, int wstat)
 	  child_lwp = add_lwp (ptid);
 	  gdb_assert (child_lwp != NULL);
 	  child_lwp->stopped = 1;
+	  child_lwp->must_set_ptrace_flags = 1;
+	  child_lwp->status_pending_p = 0;
+	  child_thr = get_lwp_thread (child_lwp);
+	  child_thr->last_resume_kind = resume_stop;
 	  parent_proc = get_thread_process (event_thr);
 	  child_proc->attached = parent_proc->attached;
 	  clone_all_breakpoints (&child_proc->breakpoints,
@@ -488,7 +493,6 @@ handle_extended_wait (struct lwp_info *event_lwp, int wstat)
 	  tdesc = xmalloc (sizeof (struct target_desc));
 	  copy_target_description (tdesc, parent_proc->tdesc);
 	  child_proc->tdesc = tdesc;
-	  child_lwp->must_set_ptrace_flags = 1;
 
 	  /* Clone arch-specific process data.  */
 	  if (the_low_target.new_fork != NULL)


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