[components/lwp] clear ref to parent on waitpid() (#7741)

Signed-off-by: shell <smokewood@qq.com>

components/drivers/ipc/pipe.c

@@ -7,6 +7,8 @@
  * Date           Author       Notes
  * 2012-09-30     Bernard      first version.
  * 2017-11-08     JasonJiaJie  fix memory leak issue when close a pipe.
+ * 2023-06-28     shell        return POLLHUP when writer closed its channel on poll()
+ *                             fix flag test on pipe_fops_open()
  */
 #include <rthw.h>
 #include <rtdevice.h>
@@ -65,12 +67,12 @@ static int pipe_fops_open(struct dfs_file *fd)
 
     rt_mutex_take(&pipe->lock, RT_WAITING_FOREVER);
 
-    if ((fd->flags & O_RDONLY) == O_RDONLY)
+    if ((fd->flags & O_ACCMODE) == O_RDONLY)
     {
         pipe->reader = 1;
     }
 
-    if ((fd->flags & O_WRONLY) == O_WRONLY)
+    if ((fd->flags & O_ACCMODE) == O_WRONLY)
     {
         pipe->writer = 1;
     }
@@ -362,6 +364,10 @@ static int pipe_fops_poll(struct dfs_file *fd, rt_pollreq_t *req)
         {
             mask |= POLLIN;
         }
+        else if (pipe->writer == 0)
+        {
+            mask = POLLHUP;
+        }
     }
 
     if (mode & 2)

components/lwp/lwp_pid.c

@@ -7,6 +7,8 @@
  * Date           Author       Notes
  * 2019-10-16     zhangjun     first version
  * 2021-02-20     lizhirui     fix warning
+ * 2023-06-26     shell        clear ref to parent on waitpid()
+ *                             Remove recycling of lwp on waitpid() and leave it to defunct routine
  */
 
 #include <rthw.h>
@@ -672,6 +674,7 @@ pid_t waitpid(pid_t pid, int *status, int options)
 
     if (ret != -1)
     {
+        /* delete from sibling list of its parent */
         struct rt_lwp **lwp_node;
 
         *status = lwp->lwp_ret;
@@ -682,9 +685,7 @@ pid_t waitpid(pid_t pid, int *status, int options)
             lwp_node = &(*lwp_node)->sibling;
         }
         (*lwp_node) = lwp->sibling;
-
-        lwp_pid_put(pid);
-        rt_free(lwp);
+        lwp->parent = RT_NULL;
     }
 
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