From ac741625b0926a0329627beca52174edd69e587b Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Thu, 14 Sep 2017 15:21:14 +0200
Subject: libio: Use FIFO for iop free list

Update #3136.
---
 cpukit/libcsupport/include/rtems/libio_.h  |  3 ++-
 cpukit/libcsupport/src/libio.c             | 23 +++++++++++++++--------
 cpukit/libcsupport/src/libio_init.c        | 10 +++++++---
 cpukit/libcsupport/src/resource_snapshot.c |  2 +-
 4 files changed, 25 insertions(+), 13 deletions(-)

(limited to 'cpukit')

diff --git a/cpukit/libcsupport/include/rtems/libio_.h b/cpukit/libcsupport/include/rtems/libio_.h
index dc1fe9808a..cf4ea78f7e 100644
--- a/cpukit/libcsupport/include/rtems/libio_.h
+++ b/cpukit/libcsupport/include/rtems/libio_.h
@@ -66,7 +66,8 @@ extern rtems_id                          rtems_libio_semaphore;
 
 extern const uint32_t rtems_libio_number_iops;
 extern rtems_libio_t rtems_libio_iops[];
-extern rtems_libio_t *rtems_libio_iop_freelist;
+extern void *rtems_libio_iop_free_head;
+extern void **rtems_libio_iop_free_tail;
 
 extern const rtems_filesystem_file_handlers_r rtems_filesystem_null_handlers;
 
diff --git a/cpukit/libcsupport/src/libio.c b/cpukit/libcsupport/src/libio.c
index 26fa7b2f67..0abb082a66 100644
--- a/cpukit/libcsupport/src/libio.c
+++ b/cpukit/libcsupport/src/libio.c
@@ -108,14 +108,21 @@ int rtems_libio_to_fcntl_flags( unsigned int flags )
 
 rtems_libio_t *rtems_libio_allocate( void )
 {
-  rtems_libio_t *iop = NULL;
+  rtems_libio_t *iop;
 
   rtems_libio_lock();
 
-  if (rtems_libio_iop_freelist) {
-    iop = rtems_libio_iop_freelist;
-    rtems_libio_iop_freelist = iop->data1;
-    memset( iop, 0, sizeof(*iop) );
+  iop = rtems_libio_iop_free_head;
+
+  if ( iop != NULL ) {
+    void *next;
+
+    next = iop->data1;
+    rtems_libio_iop_free_head = next;
+
+    if ( next == NULL ) {
+      rtems_libio_iop_free_tail = &rtems_libio_iop_free_head;
+    }
   }
 
   rtems_libio_unlock();
@@ -131,9 +138,9 @@ void rtems_libio_free(
 
   rtems_libio_lock();
 
-    iop->flags = 0;
-    iop->data1 = rtems_libio_iop_freelist;
-    rtems_libio_iop_freelist = iop;
+  iop = memset( iop, 0, sizeof( *iop ) );
+  *rtems_libio_iop_free_tail = iop;
+  rtems_libio_iop_free_tail = &iop->data1;
 
   rtems_libio_unlock();
 }
diff --git a/cpukit/libcsupport/src/libio_init.c b/cpukit/libcsupport/src/libio_init.c
index 3fa9e0995f..9c24b146ea 100644
--- a/cpukit/libcsupport/src/libio_init.c
+++ b/cpukit/libcsupport/src/libio_init.c
@@ -38,8 +38,11 @@
  *  File descriptor Table Information
  */
 
-rtems_id           rtems_libio_semaphore;
-rtems_libio_t     *rtems_libio_iop_freelist;
+rtems_id rtems_libio_semaphore;
+
+void *rtems_libio_iop_free_head;
+
+void **rtems_libio_iop_free_tail = &rtems_libio_iop_free_head;
 
 static void rtems_libio_init( void )
 {
@@ -50,10 +53,11 @@ static void rtems_libio_init( void )
 
     if (rtems_libio_number_iops > 0)
     {
-        iop = rtems_libio_iop_freelist = &rtems_libio_iops[0];
+        iop = rtems_libio_iop_free_head = &rtems_libio_iops[0];
         for (i = 0 ; (i + 1) < rtems_libio_number_iops ; i++, iop++)
           iop->data1 = iop + 1;
         iop->data1 = NULL;
+        rtems_libio_iop_free_tail = &iop->data1;
     }
 
   /*
diff --git a/cpukit/libcsupport/src/resource_snapshot.c b/cpukit/libcsupport/src/resource_snapshot.c
index d0dda9f7ca..9e026ff222 100644
--- a/cpukit/libcsupport/src/resource_snapshot.c
+++ b/cpukit/libcsupport/src/resource_snapshot.c
@@ -87,7 +87,7 @@ static int open_files(void)
 
   rtems_libio_lock();
 
-  iop = rtems_libio_iop_freelist;
+  iop = rtems_libio_iop_free_head;
   while (iop != NULL) {
     ++free_count;
 
-- 
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