Remove support for thread events without PTRACE_EVENT_CLONE in GDB

Before, on systems that did not support PTRACE_EVENT_CLONE, both GDB and
GDBServer coordinated with libthread_db.so to insert breakpoints at magic
locations in libpthread.so, in order to break at thread creation and
thread death.

Support for thread events was removed from GDBServer as patch:
https://sourceware.org/ml/gdb-patches/2015-11/msg00466.html

This patch removes support for thread events in GDB.

No regressions found on Ubuntu 14.04 x86_64.

gdb/ChangeLog:

	* breakpoint.c (remove_thread_event_breakpoints): Remove.
	* breakpoint.h (remove_thread_event_breakpoints): Remove
	declaration.
	* linux-nat.c (in_pid_list_p): Remove.
	(lin_lwp_attach_lwp): Remove.
	* linux-nat.h (lin_lwp_attach_lwp): Remove declaration.
	* linux-thread-db.c (thread_db_use_events): Remove.
	(struct thread_db_info) <td_create_bp_addr>: Remove.
	<td_death_bp_addr>: Likewise.
	<td_ta_event_addr_p>: Likewise.
	<td_ta_set_event_p>: Likewise.
	<td_ta_clear_event_p>: Likewise.
	<td_ta_event_getmsg_p>: Likewise.
	<td_thr_event_enable_p>: Likewise.
	(attach_thread): Likewise.
	(detach_thread): Likewise.
	(have_threads_callback): Likewise.
	(have_threads): Likewise.
	(enable_thread_event): Likewise.
	(enable_thread_event_reporting): Likewise.
	(try_thread_db_load_1): Remove td_ta_event_addr, td_ta_set_event,
	td_ta_clear_event, td_ta_event_getmsg, td_thr_event_enable
	initializations.
	(try_thread_db_load_1): Remove enable_thread_event_reporting call.
	(disable_thread_event_reporting): Remove.
	(record_thread): Adapt to thread_db_use_event removal.
	(detach_thread): Remove.
	(thread_db_detach): Adapt to thread_db_use_event removal.
	(check_event): Remove.
	(thread_db_wait): Adapt to thread events support removal.
	(thread_db_mourn_inferior): Likewise.
	(find_new_threads_callback): Likewise.
	(find_new_threads_once): Likewise.
	(thread_db_update_thread_list): Likewise.

1 files changed, 0 insertions, 144 deletions

diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 9bc1324..95192f6 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -345,17 +345,6 @@ add_to_pid_list (struct simple_pid_list **listp, int pid, int status)
 }
 
 static int
-in_pid_list_p (struct simple_pid_list *list, int pid)
-{
-  struct simple_pid_list *p;
-
-  for (p = list; p != NULL; p = p->next)
-    if (p->pid == pid)
-      return 1;
-  return 0;
-}
-
-static int
 pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp)
 {
   struct simple_pid_list **p;
@@ -1044,139 +1033,6 @@ linux_nat_post_attach_wait (ptid_t ptid, int first, int *cloned,
   return status;
 }
 
-/* Attach to the LWP specified by PID.  Return 0 if successful, -1 if
-   the new LWP could not be attached, or 1 if we're already auto
-   attached to this thread, but haven't processed the
-   PTRACE_EVENT_CLONE event of its parent thread, so we just ignore
-   its existance, without considering it an error.  */
-
-int
-lin_lwp_attach_lwp (ptid_t ptid)
-{
-  struct lwp_info *lp;
-  int lwpid;
-
-  gdb_assert (ptid_lwp_p (ptid));
-
-  lp = find_lwp_pid (ptid);
-  lwpid = ptid_get_lwp (ptid);
-
-  /* We assume that we're already attached to any LWP that is already
-     in our list of LWPs.  If we're not seeing exit events from threads
-     and we've had PID wraparound since we last tried to stop all threads,
-     this assumption might be wrong; fortunately, this is very unlikely
-     to happen.  */
-  if (lp == NULL)
-    {
-      int status, cloned = 0, signalled = 0;
-
-      if (ptrace (PTRACE_ATTACH, lwpid, 0, 0) < 0)
-	{
-	  if (linux_supports_tracefork ())
-	    {
-	      /* If we haven't stopped all threads when we get here,
-		 we may have seen a thread listed in thread_db's list,
-		 but not processed the PTRACE_EVENT_CLONE yet.  If
-		 that's the case, ignore this new thread, and let
-		 normal event handling discover it later.  */
-	      if (in_pid_list_p (stopped_pids, lwpid))
-		{
-		  /* We've already seen this thread stop, but we
-		     haven't seen the PTRACE_EVENT_CLONE extended
-		     event yet.  */
-		  if (debug_linux_nat)
-		    fprintf_unfiltered (gdb_stdlog,
-					"LLAL: attach failed, but already seen "
-					"this thread %s stop\n",
-					target_pid_to_str (ptid));
-		  return 1;
-		}
-	      else
-		{
-		  int new_pid;
-		  int status;
-
-		  if (debug_linux_nat)
-		    fprintf_unfiltered (gdb_stdlog,
-					"LLAL: attach failed, and haven't seen "
-					"this thread %s stop yet\n",
-					target_pid_to_str (ptid));
-
-		  /* We may or may not be attached to the LWP already.
-		     Try waitpid on it.  If that errors, we're not
-		     attached to the LWP yet.  Otherwise, we're
-		     already attached.  */
-		  gdb_assert (lwpid > 0);
-		  new_pid = my_waitpid (lwpid, &status, WNOHANG);
-		  if (new_pid == -1 && errno == ECHILD)
-		    new_pid = my_waitpid (lwpid, &status, __WCLONE | WNOHANG);
-		  if (new_pid != -1)
-		    {
-		      if (new_pid == 0)
-			{
-			  /* The child hasn't stopped for its initial
-			     SIGSTOP stop yet.  */
-			  if (debug_linux_nat)
-			    fprintf_unfiltered (gdb_stdlog,
-						"LLAL: child hasn't "
-						"stopped yet\n");
-			}
-		      else if (WIFSTOPPED (status))
-			{
-			  if (debug_linux_nat)
-			    fprintf_unfiltered (gdb_stdlog,
-						"LLAL: adding to stopped_pids\n");
-			  add_to_pid_list (&stopped_pids, lwpid, status);
-			}
-		      return 1;
-		    }
-		}
-	    }
-
-	  /* If we fail to attach to the thread, issue a warning,
-	     but continue.  One way this can happen is if thread
-	     creation is interrupted; as of Linux kernel 2.6.19, a
-	     bug may place threads in the thread list and then fail
-	     to create them.  */
-	  warning (_("Can't attach %s: %s"), target_pid_to_str (ptid),
-		   safe_strerror (errno));
-	  return -1;
-	}
-
-      if (debug_linux_nat)
-	fprintf_unfiltered (gdb_stdlog,
-			    "LLAL: PTRACE_ATTACH %s, 0, 0 (OK)\n",
-			    target_pid_to_str (ptid));
-
-      status = linux_nat_post_attach_wait (ptid, 0, &cloned, &signalled);
-      if (!WIFSTOPPED (status))
-	return 1;
-
-      lp = add_lwp (ptid);
-      lp->stopped = 1;
-      lp->last_resume_kind = resume_stop;
-      lp->cloned = cloned;
-      lp->signalled = signalled;
-      if (WSTOPSIG (status) != SIGSTOP)
-	{
-	  lp->resumed = 1;
-	  lp->status = status;
-	}
-
-      target_post_attach (ptid_get_lwp (lp->ptid));
-
-      if (debug_linux_nat)
-	{
-	  fprintf_unfiltered (gdb_stdlog,
-			      "LLAL: waitpid %s received %s\n",
-			      target_pid_to_str (ptid),
-			      status_to_str (status));
-	}
-    }
-
-  return 0;
-}
-
 static void
 linux_nat_create_inferior (struct target_ops *ops, 
 			   char *exec_file, char *allargs, char **env,