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mm/shm: Clean up the System-V shm driver

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Move shmdt functionality into shm_unmap, and use shm_unmap as the common
detach function.

Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>
This commit is contained in:
Jukka Laitinen 2023-01-10 17:03:04 +04:00 committed by Xiang Xiao
parent eef818e51f
commit 3ea7a6fb77
3 changed files with 106 additions and 140 deletions
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18
include/nuttx/mm/shm.h
View File

@ -164,23 +164,5 @@ FAR void *shm_alloc(FAR struct task_group_s *group, FAR void *vaddr,
void shm_free(FAR struct task_group_s *group, FAR void *vaddr, size_t size);
/****************************************************************************
* Name: shmdt_priv
*
* Description:
* This is the shmdt internal implementation of the shm driver. It takes
* the task group struct as a parameter and can handle both normal detach
* and cleanup during process exit.
*
* Input Parameters:
* group - A reference to the group structure from which to detach
* shmaddr - Virtual start address where the allocation starts.
* shmid - Id of the allocation
*
****************************************************************************/
int shmdt_priv(FAR struct task_group_s *group, FAR const void *shmaddr,
int shmid);
#endif /* CONFIG_MM_SHM */
#endif /* __INCLUDE_NUTTX_MM_SHM_H */

93
mm/shm/shmat.c
View File

@ -49,13 +49,100 @@ static int munmap_shm(FAR struct task_group_s *group,
{
FAR const void *shmaddr = entry->vaddr;
int shmid = entry->priv.i;
FAR struct shm_region_s *region;
pid_t pid;
unsigned int npages;
int ret;
if (mm_map_remove(get_group_mm(group), entry))
/* Remove the entry from the process' mappings */
ret = mm_map_remove(get_group_mm(group), entry);
if (ret < 0)
{
shmerr("ERROR: mm_map_remove() failed\n");
return ret;
}
return shmdt_priv(group, shmaddr, shmid);
/* Get the region associated with the shmid */
region = &g_shminfo.si_region[shmid];
DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
/* Get exclusive access to the region data structure */
ret = nxmutex_lock(&region->sr_lock);
if (ret < 0)
{
shmerr("ERROR: nxsem_wait failed: %d\n", ret);
return ret;
}
if (group)
{
/* Free the virtual address space */
shm_free(group, (FAR void *)shmaddr, region->sr_ds.shm_segsz);
/* Convert the region size to pages */
npages = MM_NPAGES(region->sr_ds.shm_segsz);
/* Detach, i.e, unmap, on shared memory region from a user virtual
* address.
*/
ret = up_shmdt((uintptr_t)shmaddr, npages);
/* Get pid of this process */
pid = group->tg_pid;
}
else
{
/* We are in the middle of process destruction and don't know the
* context
*/
pid = 0;
}
/* Decrement the count of processes attached to this region.
* If the count decrements to zero and there is a pending unlink,
* then destroy the shared memory region now and stop any further
* operations on it.
*/
DEBUGASSERT(region->sr_ds.shm_nattch > 0);
if (region->sr_ds.shm_nattch <= 1)
{
region->sr_ds.shm_nattch = 0;
if ((region->sr_flags & SRFLAG_UNLINKED) != 0)
{
shm_destroy(shmid);
return OK;
}
}
else
{
/* Just decrement the number of processes attached to the shared
* memory region.
*/
region->sr_ds.shm_nattch--;
}
/* Save the process ID of the last operation */
region->sr_ds.shm_lpid = pid;
/* Save the time of the last shmdt() */
region->sr_ds.shm_dtime = time(NULL);
/* Release our lock on the entry */
nxmutex_unlock(&region->sr_lock);
return ret;
}
/****************************************************************************

135
mm/shm/shmdt.c
View File

@ -44,132 +44,31 @@
****************************************************************************/
/****************************************************************************
* Name: shmdt_priv
* Name: shmdt
*
* Description:
* The shmdt_priv() function detaches the shared memory segment located at
* The shmdt() function detaches the shared memory segment located at
* the address specified by shmaddr from the address space of the calling
* process.
*
* Input Parameters:
* shmid - Shared memory identifier
* group - Current task_group, NULL during process exit
*
* Returned Value:
* Upon successful completion, shmdt_priv() will decrement the value of
* Upon successful completion, shmdt() will decrement the value of
* shm_nattch in the data structure associated with the shared memory ID
* of the attached shared memory segment and return 0.
*
* Otherwise, the shared memory segment will not be detached, shmdt_priv()
* Otherwise, the shared memory segment will not be detached, shmdt()
* will return -1, and errno will be set to indicate the error.
*
* - EINVAL
* The value of shmaddr is not the data segment start address of a
* shared memory segment.
*
****************************************************************************/
int shmdt_priv(FAR struct task_group_s *group, FAR const void *shmaddr,
int shmid)
{
FAR struct shm_region_s *region;
pid_t pid;
unsigned int npages;
int ret;
/* Get the region associated with the shmid */
region = &g_shminfo.si_region[shmid];
DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
/* Get exclusive access to the region data structure */
ret = nxmutex_lock(&region->sr_lock);
if (ret < 0)
{
shmerr("ERROR: nxsem_wait failed: %d\n", ret);
goto errout_with_errno;
}
if (!group)
{
pid = 0;
goto on_process_exit;
}
else
{
pid = group->tg_pid;
}
/* Free the virtual address space */
shm_free(group, (FAR void *)shmaddr, region->sr_ds.shm_segsz);
/* Convert the region size to pages */
npages = MM_NPAGES(region->sr_ds.shm_segsz);
/* Detach, i.e, unmap, on shared memory region from a user virtual
* address.
*/
ret = up_shmdt((uintptr_t)shmaddr, npages);
if (ret < 0)
{
shmerr("ERROR: up_shmdt() failed\n");
}
on_process_exit:
/* Decrement the count of processes attached to this region.
* If the count decrements to zero and there is a pending unlink,
* then destroy the shared memory region now and stop any further
* operations on it.
*/
DEBUGASSERT(region->sr_ds.shm_nattch > 0);
if (region->sr_ds.shm_nattch <= 1)
{
region->sr_ds.shm_nattch = 0;
if ((region->sr_flags & SRFLAG_UNLINKED) != 0)
{
shm_destroy(shmid);
return OK;
}
}
else
{
/* Just decrement the number of processes attached to the shared
* memory region.
*/
region->sr_ds.shm_nattch--;
}
/* Save the process ID of the last operation */
region->sr_ds.shm_lpid = pid;
/* Save the time of the last shmdt() */
region->sr_ds.shm_dtime = time(NULL);
/* Release our lock on the entry */
nxmutex_unlock(&region->sr_lock);
return OK;
errout_with_errno:
set_errno(-ret);
return ERROR;
}
int shmdt(FAR const void *shmaddr)
{
FAR struct tcb_s *tcb;
FAR struct mm_map_entry_s *entry;
FAR struct task_group_s *group;
int shmid;
int ret;
/* Get the TCB and group containing our virtual memory allocator */
@ -188,28 +87,26 @@ int shmdt(FAR const void *shmaddr)
*/
entry = mm_map_find(shmaddr, 1);
if (!entry || entry->vaddr != shmaddr)
if (entry && entry->vaddr == shmaddr)
{
DEBUGASSERT(entry->munmap);
ret = entry->munmap(group, entry, entry->vaddr, entry->length);
}
else
{
ret = -EINVAL;
shmerr("ERROR: No region matching this virtual address: %p\n",
shmaddr);
mm_map_unlock();
return -EINVAL;
}
shmid = entry->priv.i;
/* Indicate that there is no longer any mapping for this region. */
if (mm_map_remove(get_group_mm(group), entry) < 0)
{
shmerr("ERROR: mm_map_remove() failed\n");
ret = -EINVAL;
}
mm_map_unlock();
}
ret = shmdt_priv(tcb->group, shmaddr, shmid);
if (ret < 0)
{
set_errno(-ret);
ret = -1;
}
return ret;