2011-10-10 Pedro Alves <pedro@codesourcery.com>

	gdb/
	* linux-nat.c (linux_handle_extended_wait): Don't resume the new
	new clone lwp if the core asked it to stop.  Don't pass on
	unexpected signals to the new clone; leave them pending instead.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e451cb6..ec2ef4e 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2011-10-10  Pedro Alves  <pedro@codesourcery.com>
 
+       * linux-nat.c (linux_handle_extended_wait): Don't resume the new
+       new clone lwp if the core asked it to stop.  Don't pass on
+       unexpected signals to the new clone; leave them pending instead.
+
+2011-10-10  Pedro Alves  <pedro@codesourcery.com>
+
        * linux-nat.c (resume_lwp): Remove redundant debug output.
 
 2011-10-10  Pedro Alves  <pedro@codesourcery.com>

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 099f8ed..0cb4096 100644 (file)
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -2237,7 +2237,29 @@ linux_handle_extended_wait (struct lwp_info *lp, int status,
              new_lp->signalled = 1;
            }
          else
-           status = 0;
+           {
+             struct thread_info *tp;
+
+             /* When we stop for an event in some other thread, and
+                pull the thread list just as this thread has cloned,
+                we'll have seen the new thread in the thread_db list
+                before handling the CLONE event (glibc's
+                pthread_create adds the new thread to the thread list
+                before clone'ing, and has the kernel fill in the
+                thread's tid on the clone call with
+                CLONE_PARENT_SETTID).  If that happened, and the core
+                had requested the new thread to stop, we'll have
+                killed it with SIGSTOP.  But since SIGSTOP is not an
+                RT signal, it can only be queued once.  We need to be
+                careful to not resume the LWP if we wanted it to
+                stop.  In that case, we'll leave the SIGSTOP pending.
+                It will later be reported as TARGET_SIGNAL_0.  */
+             tp = find_thread_ptid (new_lp->ptid);
+             if (tp != NULL && tp->stop_requested)
+               new_lp->last_resume_kind = resume_stop;
+             else
+               status = 0;
+           }
 
          if (non_stop)
            {
@@ -2266,39 +2288,37 @@ linux_handle_extended_wait (struct lwp_info *lp, int status,
                }
            }
 
+         if (status != 0)
+           {
+             /* We created NEW_LP so it cannot yet contain STATUS.  */
+             gdb_assert (new_lp->status == 0);
+
+             /* Save the wait status to report later.  */
+             if (debug_linux_nat)
+               fprintf_unfiltered (gdb_stdlog,
+                                   "LHEW: waitpid of new LWP %ld, "
+                                   "saving status %s\n",
+                                   (long) GET_LWP (new_lp->ptid),
+                                   status_to_str (status));
+             new_lp->status = status;
+           }
+
          /* Note the need to use the low target ops to resume, to
             handle resuming with PT_SYSCALL if we have syscall
             catchpoints.  */
          if (!stopping)
            {
-             enum target_signal signo;
-
-             new_lp->stopped = 0;
              new_lp->resumed = 1;
-             new_lp->last_resume_kind = resume_continue;
 
-             signo = (status
-                      ? target_signal_from_host (WSTOPSIG (status))
-                      : TARGET_SIGNAL_0);
-
-             linux_ops->to_resume (linux_ops, pid_to_ptid (new_pid),
-                                   0, signo);
-           }
-         else
-           {
-             if (status != 0)
+             if (status == 0)
                {
-                 /* We created NEW_LP so it cannot yet contain STATUS.  */
-                 gdb_assert (new_lp->status == 0);
-
-                 /* Save the wait status to report later.  */
                  if (debug_linux_nat)
                    fprintf_unfiltered (gdb_stdlog,
-                                       "LHEW: waitpid of new LWP %ld, "
-                                       "saving status %s\n",
-                                       (long) GET_LWP (new_lp->ptid),
-                                       status_to_str (status));
-                 new_lp->status = status;
+                                       "LHEW: resuming new LWP %ld\n",
+                                       GET_LWP (new_lp->ptid));
+                 linux_ops->to_resume (linux_ops, pid_to_ptid (new_pid),
+                                       0, TARGET_SIGNAL_0);
+                 new_lp->stopped = 0;
                }
            }