source: rtems/cpukit/rtems/src/taskwakeafter.c @ f6b7b7ba

4.11
Last change on this file since f6b7b7ba was f6b7b7ba, checked in by Sebastian Huber <sebastian.huber@…>, on Jun 18, 2014 at 10:11:04 AM

score: Fix _Thread_Delay_ended() on SMP

Suppose we have two tasks A and B and two processors. Task A is about
to delete task B. Now task B calls rtems_task_wake_after(1) on the
other processor. Task B will block on the Giant lock. Task A
progresses with the task B deletion until it has to wait for
termination. Now task B obtains the Giant lock, sets its state to
STATES_DELAYING, initializes its watchdog timer and waits. Eventually
_Thread_Delay_ended() is called, but now _Thread_Get() returned NULL
since the thread is already marked as deleted. Thus task B remained
forever in the STATES_DELAYING state.

Instead of passing the thread identifier use the thread control block
directly via the watchdog user argument. This makes
_Thread_Delay_ended() also a bit more efficient.

  • Property mode set to 100644
File size: 1.1 KB
Line 
1/**
2 *  @file
3 *
4 *  @brief RTEMS Task Wake After
5 *  @ingroup ClassicTasks
6 */
7
8/*
9 *  COPYRIGHT (c) 1989-1999.
10 *  On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.rtems.org/license/LICENSE.
15 */
16
17#if HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <rtems/rtems/tasks.h>
22#include <rtems/score/threadimpl.h>
23#include <rtems/score/watchdogimpl.h>
24
25rtems_status_code rtems_task_wake_after(
26  rtems_interval ticks
27)
28{
29  /*
30   * It is critical to obtain the executing thread after thread dispatching is
31   * disabled on SMP configurations.
32   */
33  Thread_Control *executing;
34
35  _Thread_Disable_dispatch();
36    executing = _Thread_Executing;
37
38    if ( ticks == 0 ) {
39      _Thread_Yield( executing );
40    } else {
41      _Thread_Set_state( executing, STATES_DELAYING );
42      _Watchdog_Initialize(
43        &executing->Timer,
44        _Thread_Delay_ended,
45        0,
46        executing
47      );
48      _Watchdog_Insert_ticks( &executing->Timer, ticks );
49    }
50  _Thread_Enable_dispatch();
51  return RTEMS_SUCCESSFUL;
52}
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