sensor:Fixed the problem of user information lag in cross-core communication "stublist".

drivers/sensors/sensor.c

@@ -456,9 +456,17 @@ static ssize_t sensor_do_samples(FAR struct sensor_upperhalf_s *upper,
 
   if (user->state.interval == UINT32_MAX)
     {
-      ret = circbuf_peekat(&upper->buffer,
-                           user->bufferpos * upper->state.esize,
-                           buffer, len);
+      if (buffer != NULL)
+        {
+          ret = circbuf_peekat(&upper->buffer,
+                               user->bufferpos * upper->state.esize,
+                               buffer, len);
+        }
+      else
+        {
+          ret = len;
+        }
+
       user->bufferpos += nums;
       circbuf_peekat(&upper->timing,
                      (user->bufferpos - 1) * TIMING_BUF_ESIZE,
@@ -506,9 +514,17 @@ static ssize_t sensor_do_samples(FAR struct sensor_upperhalf_s *upper,
               ((user->state.generation + user->state.interval) << 1);
       if (delta >= 0)
         {
-          ret += circbuf_peekat(&upper->buffer,
-                                (pos - 1) * upper->state.esize,
-                                buffer + ret, upper->state.esize);
+          if (buffer != NULL)
+            {
+              ret += circbuf_peekat(&upper->buffer,
+                                    (pos - 1) * upper->state.esize,
+                                    buffer + ret, upper->state.esize);
+            }
+          else
+            {
+              ret += upper->state.esize;
+            }
+
           user->bufferpos = pos;
           user->state.generation += user->state.interval;
           if (ret >= len)
@@ -701,14 +717,19 @@ static ssize_t sensor_read(FAR struct file *filep, FAR char *buffer,
   FAR struct sensor_user_s *user = filep->f_priv;
   ssize_t ret;
 
-  if (!buffer || !len)
+  if (!len)
     {
       return -EINVAL;
     }
 
   nxrmutex_lock(&upper->lock);
   if (lower->ops->fetch)
     {
+      if (buffer == NULL)
+        {
+          return -EINVAL;
+        }
+
       if (!(filep->f_oflags & O_NONBLOCK))
         {
           nxrmutex_unlock(&upper->lock);
@@ -738,11 +759,18 @@ static ssize_t sensor_read(FAR struct file *filep, FAR char *buffer,
     }
   else if (lower->persist)
     {
-      /* Persistent device can get latest old data if not updated. */
+      if (buffer == NULL)
+        {
+          ret = upper->state.esize;
+        }
+      else
+        {
+          /* Persistent device can get latest old data if not updated. */
 
-      ret = circbuf_peekat(&upper->buffer,
-                           (user->bufferpos - 1) * upper->state.esize,
-                           buffer, upper->state.esize);
+          ret = circbuf_peekat(&upper->buffer,
+                               (user->bufferpos - 1) * upper->state.esize,
+                               buffer, upper->state.esize);
+        }
     }
   else
     {

drivers/sensors/sensor_rpmsg.c

@@ -1132,6 +1132,8 @@ static int sensor_rpmsg_publish_handler(FAR struct rpmsg_endpoint *ept,
 {
   FAR struct sensor_rpmsg_data_s *msg = data;
   FAR struct sensor_rpmsg_cell_s *cell;
+  FAR struct sensor_rpmsg_stub_s *stub;
+  FAR struct sensor_rpmsg_stub_s *stmp;
   FAR struct sensor_rpmsg_dev_s *dev;
   size_t written = sizeof(*msg);
 
@@ -1154,6 +1156,22 @@ static int sensor_rpmsg_publish_handler(FAR struct rpmsg_endpoint *ept,
         }
 
       dev->push_event(dev->upper, cell->data, cell->len);
+
+      /* When the remote core publishes a message, the subscribed cores will
+       * receive the message. When the subscribed core publishes a new
+       * message, it will take away the message published by the remote core,
+       * so all stublist information needs to be updated.
+       */
+
+      sensor_rpmsg_lock(dev);
+      list_for_every_entry_safe(&dev->stublist, stub, stmp,
+                                struct sensor_rpmsg_stub_s, node)
+        {
+          file_read(&stub->file, NULL, cell->len);
+        }
+
+      sensor_rpmsg_unlock(dev);
+
       written += sizeof(*cell) + cell->len + 0x7;
       written &= ~0x7;
     }