195 lines
5.8 KiB
C
195 lines
5.8 KiB
C
/****************************************************************************
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* mm/shm/shmdt.c
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*
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* Copyright (C) 2014, 2017 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 <sys/shm.h>
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#include <errno.h>
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#include <nuttx/arch.h>
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#include <nuttx/sched.h>
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#include <nuttx/mm/shm.h>
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#include "shm/shm.h"
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#ifdef CONFIG_MM_SHM
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: shmdt
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*
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* Description:
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* The shmdt() function detaches the shared memory segment located at the
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* address specified by shmaddr from the address space of the calling
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* process.
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*
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* Input Parameters:
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* shmid - Shared memory identifier
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*
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* Returned Value:
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* Upon successful completion, shmdt() will decrement the value of
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* shm_nattch in the data structure associated with the shared memory ID
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* of the attached shared memory segment and return 0.
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*
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* Otherwise, the shared memory segment will not be detached, shmdt()
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* will return -1, and errno will be set to indicate the error.
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*
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* - EINVAL
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* The value of shmaddr is not the data segment start address of a
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* shared memory segment.
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*
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****************************************************************************/
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int shmdt(FAR const void *shmaddr)
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{
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FAR struct shm_region_s *region;
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FAR struct task_group_s *group;
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FAR struct tcb_s *tcb;
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unsigned int npages;
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int shmid;
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int ret;
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/* Get the TCB and group containing our virtual memory allocator */
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tcb = sched_self();
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DEBUGASSERT(tcb && tcb->group);
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group = tcb->group;
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DEBUGASSERT(group->tg_shm.gs_handle != NULL);
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/* Perform the reverse lookup to get the shmid corresponding to this
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* shmaddr.
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*/
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for (shmid = 0;
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shmid < CONFIG_ARCH_SHM_MAXREGIONS &&
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group->tg_shm.gs_vaddr[shmid] != (uintptr_t)shmaddr;
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shmid++);
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if (shmid >= CONFIG_ARCH_SHM_MAXREGIONS)
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{
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shmerr("ERROR: No region matching this virtual address: %p\n", shmaddr);
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ret = -EINVAL;
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goto errout_with_errno;
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}
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/* Get the region associated with the shmid */
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region = &g_shminfo.si_region[shmid];
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DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
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/* Get exclusive access to the region data structure */
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ret = nxsem_wait(®ion->sr_sem);
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if (ret < 0)
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{
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shmerr("ERROR: nxsem_wait failed: %d\n", ret);
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goto errout_with_errno;
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}
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/* Free the virtual address space */
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gran_free(group->tg_shm.gs_handle, (FAR void *)shmaddr,
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region->sr_ds.shm_segsz);
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/* Convert the region size to pages */
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npages = MM_NPAGES(region->sr_ds.shm_segsz);
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/* Detach, i.e, unmap, on shared memory region from a user virtual
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* address.
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*/
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ret = up_shmdt((uintptr_t)shmaddr, npages);
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if (ret < 0)
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{
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shmerr("ERROR: up_shmdt() failed\n");
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}
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/* Indicate that there is no longer any mapping for this region. */
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group->tg_shm.gs_vaddr[shmid] = 0;
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/* Decrement the count of processes attached to this region.
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* If the count decrements to zero and there is a pending unlink,
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* then destroy the shared memory region now and stop any further
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* operations on it.
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*/
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DEBUGASSERT(region->sr_ds.shm_nattch > 0);
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if (region->sr_ds.shm_nattch <= 1)
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{
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region->sr_ds.shm_nattch = 0;
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if ((region->sr_flags & SRFLAG_UNLINKED) != 0)
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{
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shm_destroy(shmid);
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return OK;
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}
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}
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else
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{
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/* Just decrement the number of processes attached to the shared
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* memory region.
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*/
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region->sr_ds.shm_nattch--;
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}
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/* Save the process ID of the last operation */
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region->sr_ds.shm_lpid = tcb->pid;
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/* Save the time of the last shmdt() */
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region->sr_ds.shm_dtime = time(NULL);
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/* Release our lock on the entry */
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nxsem_post(®ion->sr_sem);
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return OK;
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errout_with_errno:
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set_errno(-ret);
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return ERROR;
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}
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#endif /* CONFIG_MM_SHM */
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