cancellation points are basically function. More tested is needed and additional cancellation points must be implemented before this can be merged back to master.

fs/vfs/fs_poll.c

@@ -48,6 +48,7 @@
 
 #include <nuttx/clock.h>
 #include <nuttx/semaphore.h>
+#include <nuttx/pthread.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/net/net.h>
 
@@ -365,6 +366,10 @@ int poll(FAR struct pollfd *fds, nfds_t nfds, int timeout)
   int errcode;
   int ret;
 
+  /* poll() is a cancellation point */
+
+  enter_cancellation_point();
+
   /* This semaphore is used for signaling and, hence, should not have
    * priority inheritance enabled.
    */
@@ -425,6 +430,7 @@ int poll(FAR struct pollfd *fds, nfds_t nfds, int timeout)
     }
 
   sem_destroy(&sem);
+  leave_cancellation_point();
 
   /* Check for errors */
 

fs/vfs/fs_select.c

@@ -110,6 +110,10 @@ int select(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
   int ndx;
   int ret;
 
+  /* select() is cancellation point */
+
+  enter_cancellation_point();
+
   /* How many pollfd structures do we need to allocate? */
 
   /* Initialize the descriptor list for poll() */
@@ -134,6 +138,7 @@ int select(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
   if (!pollset)
     {
       set_errno(ENOMEM);
+      leave_cancellation_point();
       return ERROR;
     }
 
@@ -280,6 +285,7 @@ int select(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
       set_errno(errcode);
     }
 
+  leave_cancellation_point();
   return ret;
 }