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211 lines
7.2 KiB
211 lines
7.2 KiB
/************************************************************************ |
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* sched/mq_notify.c |
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* |
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* Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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************************************************************************/ |
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/************************************************************************ |
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* Included Files |
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************************************************************************/ |
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#include <nuttx/config.h> |
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#include <signal.h> |
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#include <mqueue.h> |
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#include <sched.h> |
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#include <errno.h> |
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#include "os_internal.h" |
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#include "mq_internal.h" |
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/************************************************************************ |
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* Definitions |
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************************************************************************/ |
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/************************************************************************ |
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* Private Type Declarations |
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************************************************************************/ |
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/************************************************************************ |
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* Global Variables |
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************************************************************************/ |
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/************************************************************************ |
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* Private Variables |
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************************************************************************/ |
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/************************************************************************ |
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* Private Functions |
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************************************************************************/ |
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/************************************************************************ |
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* Public Functions |
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************************************************************************/ |
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/************************************************************************ |
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* Name: mq_notify |
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* |
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* Description: |
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* If "notification" is not NULL, this function connects the task with |
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* the message queue such that the specified signal will be sent to the |
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* task whenever the message changes from empty to non-empty. Only one |
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* notification can be attached to a message queue. |
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* |
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* If "notification" is NULL, the attached notification is detached (if |
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* it was held by the calling task) and the queue is available to attach |
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* another notification. |
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* |
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* When the notification is sent to the registered process, its |
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* registration will be removed. The message queue will then be |
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* available for registration. |
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* |
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* Parameters: |
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* mqdes - Message queue descriptor |
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* notification - Real-time signal structure containing: |
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* sigev_notify - Should be SIGEV_SIGNAL (but actually ignored) |
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* sigev_signo - The signo to use for the notification |
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* sigev_value - Value associated with the signal |
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* |
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* Return Value: |
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* On success mq_notify() returns 0; on error, -1 is returned, with |
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* errno set to indicate the error. |
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* |
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* EBADF The descriptor specified in mqdes is invalid. |
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* EBUSY Another process has already registered to receive notification |
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* for this message queue. |
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* EINVAL sevp->sigev_notify is not one of the permitted values; or |
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* sevp->sigev_notify is SIGEV_SIGNAL and sevp->sigev_signo is not a |
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* valid signal number. |
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* ENOMEM |
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* Insufficient memory. |
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* |
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* Assumptions: |
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* |
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* POSIX Compatibility: |
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* int mq_notify(mqd_t mqdes, const struct sigevent *notification); |
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* |
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* The notification will be sent to the registered task even if another |
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* task is waiting for the message queue to become non-empty. This is |
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* inconsistent with the POSIX specification which says, "If a process |
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* has registered for notification of message a arrival at a message |
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* queue and some process is blocked in mq_receive() waiting to receive |
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* a message when a message arrives at the queue, the arriving message |
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* message shall satisfy mq_receive()... The resulting behavior is as if |
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* the message queue remains empty, and no notification shall be sent." |
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* |
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************************************************************************/ |
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int mq_notify(mqd_t mqdes, const struct sigevent *notification) |
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{ |
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_TCB *rtcb; |
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msgq_t *msgq; |
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int errval; |
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/* Was a valid message queue descriptor provided? */ |
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if (!mqdes) |
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{ |
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/* No.. return EBADF */ |
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errval = EBADF; |
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goto errout; |
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} |
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/* Get a pointer to the message queue */ |
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sched_lock(); |
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msgq = mqdes->msgq; |
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/* Get the current process ID */ |
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rtcb = (_TCB*)g_readytorun.head; |
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/* Is there already a notification attached */ |
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if (!msgq->ntmqdes) |
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{ |
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/* No... Have we been asked to establish one? */ |
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if (notification) |
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{ |
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/* Yes... Was a valid signal number supplied? */ |
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if (!GOOD_SIGNO(notification->sigev_signo)) |
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{ |
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/* No... Return EINVAL */ |
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errval = EINVAL; |
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goto errout; |
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} |
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/* Yes... Assign it to the current task. */ |
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msgq->ntvalue.sival_ptr = notification->sigev_value.sival_ptr; |
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msgq->ntsigno = notification->sigev_signo; |
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msgq->ntpid = rtcb->pid; |
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msgq->ntmqdes = mqdes; |
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} |
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} |
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/* Yes... a notification is attached. Does this task own it? |
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* Is it trying to remove it? |
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*/ |
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else if ((msgq->ntpid != rtcb->pid) || (notification)) |
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{ |
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/* This thread does not own the notification OR it is |
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* not trying to remove it. Return EBUSY. |
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*/ |
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errval = EBUSY; |
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goto errout; |
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} |
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else |
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{ |
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/* Yes, the notification belongs to this thread. Allow the |
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* thread to detach the notification. |
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*/ |
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msgq->ntpid = INVALID_PROCESS_ID; |
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msgq->ntsigno = 0; |
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msgq->ntvalue.sival_ptr = NULL; |
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msgq->ntmqdes = NULL; |
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} |
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sched_unlock(); |
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return OK; |
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errout: |
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set_errno(errval); |
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sched_unlock(); |
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return ERROR; |
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}
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