kernel/semaphore: update some comments on nsem_inode_s

Add more description on some field of struct nsem_inode_s.

Change-Id: Icb3f2fbaeba400a163787430c145c8b47586ff13
Signed-off-by: Gregory Nutt <gnutt@nuttx.org>
[Shin: backported 6c51544e from NuttX]
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>

diff --git a/os/include/tinyara/semaphore.h b/os/include/tinyara/semaphore.h
index 4e57f4e..1af82e5 100644 (file)
--- a/os/include/tinyara/semaphore.h
+++ b/os/include/tinyara/semaphore.h
@@ -75,6 +75,10 @@
 
 struct inode;
 struct nsem_inode_s {
+       /*
+        * This must be the first element of the structure. In sem_close()
+        * this structure must be cast compatible with sem_t.
+        */
        sem_t ns_sem;                   /* The contained semaphore */
 
        /* Inode payload unique to named semaphores */