2012-07-20 Pedro Alves <palves@redhat.com>

PR threads/11692
	PR gdb/12203

	gdb/
	* infrun.c (handle_inferior_event) <new thread>: Don't special
	case minus_one_ptid.
	<TARGET_WAITKIND_SPURIOUS>: Ditto.
	* linux-thread-db.c (thread_get_info_callback): Don't return early
	if the thread is zombie.
	(thread_from_lwp): Change return type to void.  Rewrite stale
	comment.
	(attach_thread): Don't return early if the thread is zombie,
	instead set its "dying" flag.
	(thread_db_wait): Don't return TARGET_WAITKIND_SPURIOUS anymore.
	(find_new_threads_callback): Don't return early if the thread is
	zombie.

	gdb/testsuite/
	* gdb.threads/create-fail.c: New file.
	* gdb.threads/create-fail.exp: New file.

gdb/ChangeLog

@@ -1,3 +1,21 @@
+2012-07-20  Pedro Alves  <palves@redhat.com>
+
+	PR threads/11692
+	PR gdb/12203
+
+	* infrun.c (handle_inferior_event) <new thread>: Don't special
+	case minus_one_ptid.
+	<TARGET_WAITKIND_SPURIOUS>: Ditto.
+	* linux-thread-db.c (thread_get_info_callback): Don't return early
+	if the thread is zombie.
+	(thread_from_lwp): Change return type to void.  Rewrite stale
+	comment.
+	(attach_thread): Don't return early if the thread is zombie,
+	instead set its "dying" flag.
+	(thread_db_wait): Don't return TARGET_WAITKIND_SPURIOUS anymore.
+	(find_new_threads_callback): Don't return early if the thread is
+	zombie.
+
 2012-07-20  Pedro Alves  <palves@redhat.com>
 
 	* linux-nat.c (linux_nat_wait): Dump the passed in target options.

gdb/infrun.c

@@ -3194,8 +3194,7 @@ handle_inferior_event (struct execution_control_state *ecs)
     }
 
   if (ecs->ws.kind != TARGET_WAITKIND_EXITED
-      && ecs->ws.kind != TARGET_WAITKIND_SIGNALLED
-      && !ptid_equal (ecs->ptid, minus_one_ptid))
+      && ecs->ws.kind != TARGET_WAITKIND_SIGNALLED)
     {
       ecs->event_thread = find_thread_ptid (ecs->ptid);
       /* If it's a new thread, add it to the thread database.  */
@@ -3363,8 +3362,7 @@ handle_inferior_event (struct execution_control_state *ecs)
     case TARGET_WAITKIND_SPURIOUS:
       if (debug_infrun)
         fprintf_unfiltered (gdb_stdlog, "infrun: TARGET_WAITKIND_SPURIOUS\n");
-      if (!ptid_equal (ecs->ptid, inferior_ptid)
-	  && !ptid_equal (ecs->ptid, minus_one_ptid))
+      if (!ptid_equal (ecs->ptid, inferior_ptid))
 	context_switch (ecs->ptid);
       resume (0, GDB_SIGNAL_0);
       prepare_to_wait (ecs);

gdb/linux-thread-db.c

@@ -422,11 +422,6 @@ thread_get_info_callback (const td_thrhandle_t *thp, void *argp)
   thread_ptid = ptid_build (info->pid, ti.ti_lid, 0);
   inout->thread_info = find_thread_ptid (thread_ptid);
 
-  /* In the case of a zombie thread, don't continue.  We don't want to
-     attach to it thinking it is a new thread.  */
-  if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
-    return TD_THR_ZOMBIE;
-
   if (inout->thread_info == NULL)
     {
       /* New thread.  Attach to it now (why wait?).  */
@@ -441,9 +436,9 @@ thread_get_info_callback (const td_thrhandle_t *thp, void *argp)
   return 0;
 }
 
-/* Convert between user-level thread ids and LWP ids.  */
+/* Fetch the user-level thread id of PTID.  */
 
-static ptid_t
+static void
 thread_from_lwp (ptid_t ptid)
 {
   td_thrhandle_t th;
@@ -467,22 +462,10 @@ thread_from_lwp (ptid_t ptid)
     error (_("Cannot find user-level thread for LWP %ld: %s"),
 	   GET_LWP (ptid), thread_db_err_str (err));
 
-  /* Fetch the thread info.  If we get back TD_THR_ZOMBIE, then the
-     event thread has already died.  If another gdb interface has called
-     thread_alive() previously, the thread won't be found on the thread list
-     anymore.  In that case, we don't want to process this ptid anymore
-     to avoid the possibility of later treating it as a newly
-     discovered thread id that we should add to the list.  Thus,
-     we return a -1 ptid which is also how the thread list marks a
-     dead thread.  */
+  /* Long-winded way of fetching the thread info.  */
   io.thread_db_info = info;
   io.thread_info = NULL;
-  if (thread_get_info_callback (&th, &io) == TD_THR_ZOMBIE
-      && io.thread_info == NULL)
-    return minus_one_ptid;
-
-  gdb_assert (ptid_get_tid (ptid) == 0);
-  return ptid;
+  thread_get_info_callback (&th, &io);
 }
 
 
@@ -1260,9 +1243,6 @@ attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
   if (target_has_execution)
     check_thread_signals ();
 
-  if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
-    return 0;			/* A zombie thread -- do not attach.  */
-
   /* Under GNU/Linux, we have to attach to each and every thread.  */
   if (target_has_execution
       && tp == NULL)
@@ -1297,6 +1277,8 @@ attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
   gdb_assert (ti_p->ti_tid != 0);
   private->th = *th_p;
   private->tid = ti_p->ti_tid;
+  if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
+    private->dying = 1;
 
   /* Add the thread to GDB's thread list.  */
   if (tp == NULL)
@@ -1514,15 +1496,8 @@ thread_db_wait (struct target_ops *ops,
 
   if (have_threads (ptid))
     {
-      /* Change ptids back into the higher level PID + TID format.  If
-	 the thread is dead and no longer on the thread list, we will
-	 get back a dead ptid.  This can occur if the thread death
-	 event gets postponed by other simultaneous events.  In such a
-	 case, we want to just ignore the event and continue on.  */
-
-      ptid = thread_from_lwp (ptid);
-      if (GET_PID (ptid) == -1)
-	ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
+      /* Fill in the thread's user-level thread id.  */
+      thread_from_lwp (ptid);
     }
 
   return ptid;
@@ -1567,9 +1542,6 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
     error (_("find_new_threads_callback: cannot get thread info: %s"),
 	   thread_db_err_str (err));
 
-  if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
-    return 0;			/* A zombie -- ignore.  */
-
   if (ti.ti_tid == 0)
     {
       /* A thread ID of zero means that this is the main thread, but

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2012-07-20  Pedro Alves  <palves@redhat.com>
+
+	PR threads/11692
+	PR gdb/12203
+
+	* gdb.threads/create-fail.c: New file.
+	* gdb.threads/create-fail.exp: New file.
+
 2012-07-19  Pedro Alves  <palves@redhat.com>
 
 	* config/monitor.exp (gdb_load): Remove redundant ';' in for loop.

gdb/testsuite/gdb.threads/create-fail.c

@@ -0,0 +1,119 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sched.h>
+#include <errno.h>
+#include <string.h>
+#include <assert.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <assert.h>
+
+/* Count the number of tasks/threads in the PID thread group.  */
+
+static int
+count_tasks (pid_t pid)
+{
+  char path[100];
+  int count;
+  DIR *d;
+
+  snprintf (path, sizeof (path), "/proc/%d/task/", (int) pid);
+  d = opendir (path);
+  if (d == NULL)
+    return -1;
+
+  for (count = 0; readdir (d) != NULL; count++)
+    ;
+  closedir (d);
+
+  /* Account for '.' and '..'.  */
+  assert (count > 2);
+  return count - 2;
+}
+
+pthread_attr_t attr[CPU_SETSIZE];
+pthread_t thr[CPU_SETSIZE];
+
+static void *
+mythread (void *_arg)
+{
+  return NULL;
+}
+
+int
+main ()
+{
+  int i;
+
+  for (i = 0; i < CPU_SETSIZE; i++)
+    {
+      cpu_set_t set;
+      int ret;
+
+      pthread_attr_init (&attr[i]);
+      CPU_ZERO_S (sizeof (set), &set);
+      CPU_SET_S (i, sizeof (set), &set);
+
+      ret = pthread_attr_setaffinity_np (&attr[i], sizeof (set), &set);
+      if (ret != 0)
+	{
+	  fprintf (stderr, "set_affinity: %d: %s\n", ret, strerror (ret));
+	  exit (3);
+	}
+      ret = pthread_create (&thr[i], &attr[i], mythread, NULL);
+      /* Should fail with EINVAL at some point.  */
+      if (ret != 0)
+	{
+	  unsigned long t;
+
+	  fprintf (stderr, "pthread_create: %d: %s\n", ret, strerror (ret));
+
+	  /* Wait for all threads to exit.  pthread_create spawns a
+	     clone thread even in the failing case, as it can only try
+	     to set the affinity after creating the thread.  That new
+	     thread is immediately canceled (because setting the
+	     affinity fails), by killing it with a SIGCANCEL signal,
+	     which may end up in pthread_cancel/unwind paths, which
+	     may trigger a libgcc_s.so load, making the thread hit the
+	     solib-event breakpoint.  Now, if we would let the program
+	     exit without waiting, sometimes it would happen that the
+	     inferior exits just while we're handling the solib-event,
+	     resulting in errors being thrown due to failing ptrace
+	     call fails (with ESCHR), breaking the test.  */
+	  t = 16;
+	  while (count_tasks (getpid ()) > 1)
+	    {
+	      usleep (t);
+
+	      if (t < 256)
+		t *= 2;
+	    }
+
+	  /* Normal exit, because this is what we are expecting.  */
+	  exit (0);
+	}
+    }
+
+  /* Should not normally be reached.  */
+  exit (1);
+}

gdb/testsuite/gdb.threads/create-fail.exp

@@ -0,0 +1,53 @@
+# Copyright (C) 2012 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# On GNU/Linux, a creating a thread bound to an unexisting cpu spawns
+# the clone child thread for a bit, which is then immediately
+# cancelled.  The spawned child may trigger a dlopen (for libgcc_s)
+# while being cancelled, which results in a trap being reported to
+# GDB, for a thread that libthread_db considers to be TD_THR_ZOMBIE.
+# Make sure we handle that scenario properly.
+
+standard_testfile
+set executable ${testfile}
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    return -1
+}
+
+set iterations 10
+for {set i 1} {$i <= $iterations} {incr i} {
+    with_test_prefix "iteration $i" {
+
+	clean_restart ${executable}
+
+	if ![runto_main] {
+	    return -1
+	}
+
+	set test "run till end"
+	gdb_test_multiple "continue" "$test" {
+	    -re "exited with code 01.*$gdb_prompt $" {
+		pass "$test"
+	    }
+	    -re "exited with code 02.*$gdb_prompt $" {
+		unsupported "$test (too many CPUs for test?)"
+	    }
+	    -re "exited normally.*$gdb_prompt $" {
+		pass "$test"
+	    }
+	}
+    }
+}