nuttx/can: Modify poll logic to bind can_reader_s and pollfd.

For clearing some variables corresponding with the pollfds of the felip in can_close API, we modify poll logic by binding can_reader_s and pollfd.

Signed-off-by: zhaohaiyang1 <zhaohaiyang1@xiaomi.com>

drivers/can/Kconfig

@@ -157,13 +157,6 @@ config CAN_LOOPBACK
 		driver does support loopback mode, the setting will enable it. (If the
 		driver does not, this setting will have no effect).
 
-config CAN_NPOLLWAITERS
-	int "Number of poll waiters"
-	default 2
-	---help---
-		The maximum number of threads that may be waiting on the
-		poll method.
-
 config CAN_USE_RTR
 	bool "Include RTR in CAN header"
 	default n

drivers/can/can.c

@@ -308,6 +308,21 @@ static int can_close(FAR struct file *filep)
       if (((FAR struct can_reader_s *)node) ==
           ((FAR struct can_reader_s *)filep->f_priv))
         {
+          FAR struct can_reader_s *reader = (FAR struct can_reader_s *)node;
+          FAR struct can_rxfifo_s *fifo   = &reader->fifo;
+
+          /* Unlock the binary semaphore, waking up can_read if it
+           * is blocked.
+           */
+
+          nxsem_post(&fifo->rx_sem);
+
+          /* Notify specfic poll/select waiter that they can read from the
+           * cd_recv buffer
+           */
+
+          poll_notify(&reader->cd_fds, 1, POLLHUP);
+          reader->cd_fds = NULL;
           list_delete(node);
           kmm_free(node);
           break;
@@ -953,13 +968,12 @@ static int can_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 static int can_poll(FAR struct file *filep, FAR struct pollfd *fds,
                     bool setup)
 {
-  FAR struct inode *inode = filep->f_inode;
-  FAR struct can_dev_s *dev = inode->i_private;
-  FAR struct can_reader_s *reader = NULL;
-  pollevent_t eventset = 0;
-  irqstate_t flags;
-  int ret;
-  int i;
+  FAR struct inode        *inode    = filep->f_inode;
+  FAR struct can_dev_s    *dev      = inode->i_private;
+  FAR struct can_reader_s *reader   = NULL;
+  pollevent_t              eventset = 0;
+  int                      ret      = OK;
+  irqstate_t               flags;
 
   /* Some sanity checking */
 
@@ -999,27 +1013,20 @@ static int can_poll(FAR struct file *filep, FAR struct pollfd *fds,
        * slot for the poll structure reference.
        */
 
-      for (i = 0; i < CONFIG_CAN_NPOLLWAITERS; i++)
-        {
-          /* Find an available slot */
-
-          if (dev->cd_fds[i] == NULL)
-            {
-              /* Bind the poll structure and this slot */
-
-              dev->cd_fds[i] = fds;
-              fds->priv       = &dev->cd_fds[i];
-              break;
-            }
-        }
-
-      if (i >= CONFIG_CAN_NPOLLWAITERS)
+      if (reader->cd_fds != NULL)
         {
           fds->priv = NULL;
           ret       = -EBUSY;
           goto errout;
         }
 
+      /* Have found an available slot,
+       * bind the poll structure and this slot
+       */
+
+      reader->cd_fds = fds;
+      fds->priv      = &reader->cd_fds;
+
       /* Should we immediately notify on any of the requested events?
        * First, check if the sender is full.
        */
@@ -1268,6 +1275,11 @@ int can_receive(FAR struct can_dev_s *dev, FAR struct can_hdr_s *hdr,
               nxsem_post(&fifo->rx_sem);
             }
 
+          /* Notify specfic poll/select waiter that they can read from the
+           * cd_recv buffer
+           */
+
+          poll_notify(&reader->cd_fds, 1, POLLIN);
           ret = OK;
         }
 #ifdef CONFIG_CAN_ERRORS
@@ -1280,15 +1292,6 @@ int can_receive(FAR struct can_dev_s *dev, FAR struct can_hdr_s *hdr,
 #endif
     }
 
-  /* Notify all poll/select waiters that they can read from the
-   * cd_recv buffer
-   */
-
-  if (ret == OK)
-    {
-      poll_notify(dev->cd_fds, CONFIG_CAN_NPOLLWAITERS, POLLIN);
-    }
-
   leave_critical_section(flags);
   return ret;
 }
@@ -1365,6 +1368,7 @@ int can_receive(FAR struct can_dev_s *dev, FAR struct can_hdr_s *hdr,
 
 int can_txdone(FAR struct can_dev_s *dev)
 {
+  FAR struct list_node *node;
   int ret = -ENOENT;
   irqstate_t flags;
 
@@ -1398,7 +1402,11 @@ int can_txdone(FAR struct can_dev_s *dev)
        * buffer
        */
 
-      poll_notify(dev->cd_fds, CONFIG_CAN_NPOLLWAITERS, POLLOUT);
+      list_for_every(&dev->cd_readers, node)
+        {
+          FAR struct can_reader_s *reader = (FAR struct can_reader_s *)node;
+          poll_notify(&reader->cd_fds, 1, POLLOUT);
+        }
 
       /* Are there any threads waiting for space in the sender? */
 

include/nuttx/can/can.h

@@ -801,6 +801,7 @@ struct can_reader_s
 {
   struct list_node     list;
   struct can_rxfifo_s  fifo;             /* Describes receive FIFO */
+  FAR struct pollfd   *cd_fds;
 };
 
 struct can_transv_s
@@ -825,7 +826,6 @@ struct can_dev_s
   FAR const struct can_ops_s *cd_ops;    /* Arch-specific operations */
   FAR void            *cd_priv;          /* Used by the arch-specific logic */
   FAR struct can_transv_s *cd_transv;    /* Describes CAN transceiver */
-  FAR struct pollfd   *cd_fds[CONFIG_CAN_NPOLLWAITERS];
 };
 
 /* Structures used with ioctl calls */