1 files changed, 227 insertions, 0 deletions
diff --git a/nuttx/sched/group_join.c b/nuttx/sched/group_join.c
new file mode 100644
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+++ b/nuttx/sched/group_join.c
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+/*****************************************************************************
+ * sched/group_join.c
+ *
+ *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Included Files
+ *****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <assert.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+
+#include "group_internal.h"
+#include "env_internal.h"
+
+#ifdef HAVE_TASK_GROUP
+
+/*****************************************************************************
+ * Pre-processor Definitions
+ *****************************************************************************/
+/* Is this worth making a configuration option? */
+
+#define GROUP_REALLOC_MEMBERS 4
+
+/*****************************************************************************
+ * Private Types
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Private Data
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Private Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Public Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Name: group_bind
+ *
+ * Description:
+ *   A thread joins the group when it is created.  This is a two step process,
+ *   first, the group must bound to the new threads TCB.  group_bind() does
+ *   this (at the return from group_join, things are a little unstable:  The
+ *   group has been bound, but tg_nmembers hs not yet been incremented).
+ *   Then, after the new thread is initialized and has a PID assigned to it,
+ *   group_join() is called, incrementing the tg_nmembers count on the group.  
+ *
+ * Parameters:
+ *   tcb - The TCB of the new "child" task that need to join the group.
+ *
+ * Return Value:
+ *   0 (OK) on success; a negated errno value on failure.
+ *
+ * Assumptions:
+ * - The parent task from which the group will be inherited is the task at
+ *   the thead of the ready to run list.
+ * - Called during thread creation in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+int group_bind(FAR _TCB *tcb)
+{
+  FAR _TCB *ptcb = (FAR _TCB *)g_readytorun.head;
+
+  DEBUGASSERT(ptcb && tcb && ptcb->group && !tcb->group);
+
+  /* Copy the group reference from the parent to the child */
+
+  tcb->group = ptcb->group;
+  return OK;
+}
+
+/*****************************************************************************
+ * Name: group_join
+ *
+ * Description:
+ *   A thread joins the group when it is created.  This is a two step process,
+ *   first, the group must bound to the new threads TCB.  group_bind() does
+ *   this (at the return from group_join, things are a little unstable:  The
+ *   group has been bound, but tg_nmembers hs not yet been incremented).
+ *   Then, after the new thread is initialized and has a PID assigned to it,
+ *   group_join() is called, incrementing the tg_nmembers count on the group.  
+ *
+ * Parameters:
+ *   tcb - The TCB of the new "child" task that need to join the group.
+ *
+ * Return Value:
+ *   0 (OK) on success; a negated errno value on failure.
+ *
+ * Assumptions:
+ * - The parent task from which the group will be inherited is the task at
+ *   the thead of the ready to run list.
+ * - Called during thread creation in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+int group_join(FAR _TCB *tcb)
+{
+  FAR struct task_group_s *group;
+#ifdef HAVE_GROUP_MEMBERS
+  int ret;
+#endif
+
+  DEBUGASSERT(tcb && tcb->group &&
+              tcb->group->tg_nmembers < UINT8_MAX);
+
+  /* Get the group from the TCB */
+
+  group = tcb->group;
+
+#ifdef HAVE_GROUP_MEMBERS
+  /* Add the member to the group */
+
+  ret = group_addmember(group, tcb->pid);
+  if (ret < 0)
+    {
+      return ret;
+    }
+#endif
+
+  group->tg_nmembers++;
+  return OK;
+}
+
+/*****************************************************************************
+ * Name: group_addmember
+ *
+ * Description:
+ *   Add a new member to a group.  
+ *
+ * Parameters:
+ *   group - The task group to add the new member
+ *   pid - The new member
+ *
+ * Return Value:
+ *   0 (OK) on success; a negated errno value on failure.
+ *
+ * Assumptions:
+ *   Called during thread creation and during reparenting in a safe context.
+ *   No special precautions are required here.
+ *
+ *****************************************************************************/
+
+#ifdef HAVE_GROUP_MEMBERS
+int group_addmember(FAR struct task_group_s *group, pid_t pid)
+{
+  DEBUGASSERT(group && group->tg_nmembers < UINT8_MAX);
+
+  /* Will we need to extend the size of the array of groups? */
+
+  if (group->tg_nmembers >= group->tg_mxmembers)
+    {
+      FAR pid_t *newmembers;
+      unsigned int newmax;
+
+      /* Yes... reallocate the array of members */
+
+      newmax = group->tg_mxmembers + GROUP_REALLOC_MEMBERS;
+      if (newmax > UINT8_MAX)
+        {
+          newmax = UINT8_MAX;
+        }
+
+      newmembers = (FAR pid_t *)
+        krealloc(group->tg_members, sizeof(pid_t) * newmax);
+
+      if (!newmembers)
+        {
+          return -ENOMEM;
+        }
+
+      /* Save the new number of members in the reallocated members array */
+
+      group->tg_members   = newmembers;
+      group->tg_mxmembers = newmax;
+    }
+
+  /* Assign this new pid to the group. */
+
+  group->tg_members[group->tg_nmembers] = pid;
+  return OK;
+}
+#endif /* HAVE_GROUP_MEMBERS */
+
+#endif /* HAVE_TASK_GROUP */