Completes the implemenation of the core shared memory logic: shmget(), shmctl(), shmat(), and shmdt(). This is still some unfinish platform-specific code that needs to be done before we can begin testing.

2 files changed, 223 insertions, 21 deletions

diff --git a/nuttx/mm/shm/shmat.c b/nuttx/mm/shm/shmat.c
index a76327e13..3a9bc4c08 100755..100644
--- a/nuttx/mm/shm/shmat.c
+++ b/nuttx/mm/shm/shmat.c
@@ -42,6 +42,12 @@
 #include <sys/shm.h>
 #include <errno.h>
 
+#include <nuttx/sched.h>
+#include <nuttx/arch.h>
+#include <nuttx/pgalloc.h>
+
+#include "shm/shm.h"
+
 #ifdef CONFIG_MM_SHM
 
 /****************************************************************************
@@ -94,7 +100,8 @@
  * Returned Value:
  *   Upon successful completion, shmat() will increment the value of
  *   shm_nattch in the data structure associated with the shared memory ID
- *   of the attached shared memory segment and return the segment's start address.
+ *   of the attached shared memory segment and return the segment's start
+ *   address.
  *
  *   Otherwise, the shared memory segment will not be attached, shmat() will
  *   return -1, and errno will be set to indicate the error.
@@ -119,8 +126,91 @@
 
 FAR void *shmat(int shmid, FAR const void *shmaddr, int shmflg)
 {
-#warning Not implemented
-  set_errno(ENOSYS);
+  FAR struct shm_region_s *region;
+  FAR struct task_group_s *group;
+  FAR struct tcb_s *tcb;
+  uintptr_t vaddr;
+  unsigned int npages;
+  int ret;
+
+  /* Get the region associated with the shmid */
+
+  DEBUGASSERT(shmid >= 0 && shmid < CONFIG_ARCH_SHM_MAXREGIONS);
+  region =  &g_shminfo.si_region[shmid];
+  DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
+
+  /* Get the TCB and group containing our virtual memory allocator */
+
+  tcb = sched_self();
+  DEBUGASSERT(tcb && tcb->group);
+  group = tcb->group;
+  DEBUGASSERT(group->tg_shm.gs_handle != NULL &&
+              group->tg_shm.gs_vaddr[shmid] == 0);
+
+  /* Get exclusive access to the region data structure */
+
+  ret = sem_wait(&region->sr_sem);
+  if (ret < 0)
+    {
+      shmdbg("sem_wait failed: %d\n", ret);
+      goto errout;
+    }
+
+  /* Set aside a virtual address space to span this physical region */
+
+  vaddr = (uintptr_t)gran_alloc(group->tg_shm.gs_handle,
+                                region->sr_ds.shm_segsz);
+  if (vaddr == 0)
+    {
+      shmdbg("gran_alloc() failed\n");
+      ret = -ENOMEM;
+      goto errout_with_semaphore;
+    }
+
+  /* Convert the region size to pages */
+
+  npages = MM_PGALIGNUP(region->sr_ds.shm_segsz);
+
+  /* Attach, i.e, map, on shared memory region to the user virtual address. */
+
+  ret = up_shmat(region->sr_pages, npages, vaddr);
+  if (ret < 0)
+    {
+      shmdbg("up_shmat() failed\n");
+      goto errout_with_vaddr;
+    }
+
+  /* Save the virtual address of the region.  We will need that in shmat()
+   * to do the reverse lookup:  Give the virtual address of the region to
+   * detach, we need to get the region table index.
+   */
+
+  group->tg_shm.gs_vaddr[shmid] = vaddr;
+
+  /* Increment the count of processes attached to this region */
+
+  region->sr_ds.shm_nattch++;
+
+  /* Save the process ID of the the last operation */
+
+  region->sr_ds.shm_lpid = tcb->pid;
+
+  /* Save the time of the last shmat() */
+
+  region->sr_ds.shm_atime = time(NULL);
+
+  /* Release our lock on the entry */
+
+  sem_post(&region->sr_sem);
+  return (FAR void *)vaddr;
+
+errout_with_vaddr:
+  gran_free(group->tg_shm.gs_handle, (FAR void *)vaddr,
+            region->sr_ds.shm_segsz);
+errout_with_semaphore:
+  sem_post(&region->sr_sem);
+  set_errno(-ret);
+errout:
   return (FAR void *)ERROR;
 }
 
diff --git a/nuttx/mm/shm/shmdt.c b/nuttx/mm/shm/shmdt.c
index a350e5ca0..8acfc6197 100755..100644
--- a/nuttx/mm/shm/shmdt.c
+++ b/nuttx/mm/shm/shmdt.c
@@ -33,17 +33,23 @@
  *
  ****************************************************************************/
 
-/****************************************************************************

- * Included Files

- ****************************************************************************/

-

-#include <nuttx/config.h>

-

-#include <sys/shm.h>

-#include <errno.h>

-

-#ifdef CONFIG_MM_SHM

-

+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/shm.h>
+#include <errno.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/sched.h>
+#include <nuttx/shm.h>
+
+#include "shm/shm.h"
+
+#ifdef CONFIG_MM_SHM
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -87,13 +93,119 @@
  *     The value of shmaddr is not the data segment start address of a
  *     shared memory segment.
  *
- ****************************************************************************/

-

+ ****************************************************************************/
+
 int shmdt(FAR const void *shmaddr)
-{

-#warning Not implemented

-  set_errno(ENOSYS);

-  return ERROR;

-}

+{
+  FAR struct shm_region_s *region;
+  FAR struct task_group_s *group;
+  FAR struct tcb_s *tcb;
+  unsigned int npages;
+  int shmid;
+  int ret;
+
+  /* Get the TCB and group containing our virtual memory allocator */
+
+  tcb = sched_self();
+  DEBUGASSERT(tcb && tcb->group);
+  group = tcb->group;
+  DEBUGASSERT(group->tg_shm.gs_handle != NULL);
+
+  /* Perform the reverse lookup to get the shmid corresponding to this
+   * shmaddr.
+   */
+
+  for (shmid = 0;
+       shmid < CONFIG_ARCH_SHM_MAXREGIONS &&
+       group->tg_shm.gs_vaddr[shmid] != (uintptr_t)shmaddr;
+       shmid++);
+
+  if (shmid >= CONFIG_ARCH_SHM_MAXREGIONS)
+    {
+      shmdbg("No region matching this virtual address: %p\n", shmaddr);
+      ret = -EINVAL;
+      goto errout_with_errno;
+    }
+
+  /* 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 = sem_wait(&region->sr_sem);
+  if (ret < 0)
+    {
+      shmdbg("sem_wait failed: %d\n", ret);
+      goto errout;
+    }
+
+  /* Free the virtual address space */
+
+  gran_free(group->tg_shm.gs_handle, (FAR void *)shmaddr,
+            region->sr_ds.shm_segsz);
+
+  /* Convert the region size to pages */
+
+  npages = MM_PGALIGNUP(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)
+    {
+      shmdbg("up_shmdt() failed\n");
+    }
+
+  /* Indicate that there is no longer any mapping for this region. */
+
+  group->tg_shm.gs_vaddr[shmid] = 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 the last operation */
+
+  region->sr_ds.shm_lpid = tcb->pid;
+
+  /* Save the time of the last shmdt() */
+
+  region->sr_ds.shm_dtime = time(NULL);
+
+  /* Release our lock on the entry */
+
+  sem_post(&region->sr_sem);
+  return OK;
+
+errout_with_errno:
+  set_errno(-ret);
+errout:
+  return ERROR;
+}
 
 #endif /* CONFIG_MM_SHM */