linux-nat: introduce pending_status_str

I noticed that some debug log output printing an lwp's pending status
wasn't considering lp->waitstatus.  This fixes it, by introducing a
new pending_status_str function.

Also fix the comment in gdb/linux-nat.h describing
lwp_info::waitstatus and details the description of lwp_info::status
while at it.

Change-Id: I66e5c7a363d30a925b093b195d72925ce5b6b980
Approved-By: Andrew Burgess <aburgess@redhat.com>

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index fd537d7a1d36e1b3675ca877f9fbaf27bb2f413e..fd80fd975c144be9bcbb39971a711b00742f3ac4 100644 (file)
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -255,6 +255,19 @@ is_leader (lwp_info *lp)
   return lp->ptid.pid () == lp->ptid.lwp ();
 }
 
+/* Convert an LWP's pending status to a std::string.  */
+
+static std::string
+pending_status_str (lwp_info *lp)
+{
+  gdb_assert (lwp_status_pending_p (lp));
+
+  if (lp->waitstatus.kind () != TARGET_WAITKIND_IGNORE)
+    return lp->waitstatus.to_string ();
+  else
+    return status_to_str (lp->status);
+}
+
 \f
 /* LWP accessors.  */
 
@@ -1647,8 +1660,8 @@ linux_nat_target::resume (ptid_t scope_ptid, int step, enum gdb_signal signo)
         this thread with a signal?  */
       gdb_assert (signo == GDB_SIGNAL_0);
 
-      linux_nat_debug_printf ("Short circuiting for status 0x%x",
-                             lp->status);
+      linux_nat_debug_printf ("Short circuiting for status %s",
+                             pending_status_str (lp).c_str ());
 
       if (target_can_async_p ())
        {
@@ -3137,7 +3150,7 @@ linux_nat_wait_1 (ptid_t ptid, struct target_waitstatus *ourstatus,
   if (lp != NULL)
     {
       linux_nat_debug_printf ("Using pending wait status %s for %s.",
-                             status_to_str (lp->status).c_str (),
+                             pending_status_str (lp).c_str (),
                              lp->ptid.to_string ().c_str ());
     }
 

diff --git a/gdb/linux-nat.h b/gdb/linux-nat.h
index 45534c92386edc4ac1c315306ff3a35bbce89db7..770fe9244277ab2cd04def9293508969ea3861fb 100644 (file)
--- a/gdb/linux-nat.h
+++ b/gdb/linux-nat.h
@@ -232,7 +232,9 @@ struct lwp_info : intrusive_list_node<lwp_info>
   /* The last resume GDB requested on this thread.  */
   resume_kind last_resume_kind = resume_continue;
 
-  /* If non-zero, a pending wait status.  */
+  /* If non-zero, a pending wait status.  A pending process exit is
+     recorded in WAITSTATUS, because W_EXITCODE(0,0) happens to be
+     0.  */
   int status = 0;
 
   /* When 'stopped' is set, this is where the lwp last stopped, with
@@ -260,9 +262,10 @@ struct lwp_info : intrusive_list_node<lwp_info>
   /* Non-zero if we expect a duplicated SIGINT.  */
   int ignore_sigint = 0;
 
-  /* If WAITSTATUS->KIND != TARGET_WAITKIND_SPURIOUS, the waitstatus
-     for this LWP's last event.  This may correspond to STATUS above,
-     or to a local variable in lin_lwp_wait.  */
+  /* If WAITSTATUS->KIND != TARGET_WAITKIND_IGNORE, the waitstatus for
+     this LWP's last event.  This usually corresponds to STATUS above,
+     however because W_EXITCODE(0,0) happens to be 0, a process exit
+     will be recorded here, while 'status == 0' is ambiguous.  */
   struct target_waitstatus waitstatus;
 
   /* Signal whether we are in a SYSCALL_ENTRY or