libio: Remove special-case reference count

The top-level IO library structures should contain no special-case data.

Update #2859.

3 files changed, 2 insertions, 72 deletions

diff --git a/cpukit/libcsupport/include/rtems/libio.h b/cpukit/libcsupport/include/rtems/libio.h
index 8226d18ba2..7022de671c 100644
--- a/cpukit/libcsupport/include/rtems/libio.h
+++ b/cpukit/libcsupport/include/rtems/libio.h
@@ -1320,7 +1320,6 @@ struct rtems_libio_tt {
   rtems_driver_name_t                    *driver;
   off_t                                   offset;    /* current offset into file */
   uint32_t                                flags;
-  uint32_t                                mapping_refcnt; /* current mappings */
   rtems_filesystem_location_info_t        pathinfo;
   uint32_t                                data0;     /* private to "driver" */
   void                                   *data1;     /* ... */
diff --git a/cpukit/libcsupport/include/rtems/libio_.h b/cpukit/libcsupport/include/rtems/libio_.h
index 695a4c45a5..c2fb975bf7 100644
--- a/cpukit/libcsupport/include/rtems/libio_.h
+++ b/cpukit/libcsupport/include/rtems/libio_.h
@@ -304,47 +304,6 @@ void rtems_libio_free(
   rtems_libio_t *iop
 );
 
-/**
- * Garbage collects the free libio in case it was previously freed but there
- * were still references to it.
- */
-void rtems_libio_check_deferred_free( rtems_libio_t *iop );
-
-/**
- * Increment the reference count tracking number of mmap mappings of a file.
- * Returns the updated reference count value.
- */
-static inline uint32_t rtems_libio_increment_mapping_refcnt(rtems_libio_t *iop)
-{
-  uint32_t refcnt;
-  rtems_libio_lock();
-  refcnt = ++iop->mapping_refcnt;
-  rtems_libio_unlock();
-  return refcnt;
-}
-
-/**
- * Decrement the reference count tracking number of mmap mappings of a file.
- * Returns the updated reference count value.
- */
-static inline uint32_t rtems_libio_decrement_mapping_refcnt(rtems_libio_t *iop)
-{
-  uint32_t refcnt;
-  rtems_libio_lock();
-  refcnt = --iop->mapping_refcnt;
-  rtems_libio_unlock();
-  return refcnt;
-}
-
-static inline bool rtems_libio_is_mapped(rtems_libio_t *iop)
-{
-  bool is_mapped;
-  rtems_libio_lock();
-  is_mapped = iop->mapping_refcnt != 0;
-  rtems_libio_unlock();
-  return is_mapped;
-}
-
 /*
  *  File System Routine Prototypes
  */
diff --git a/cpukit/libcsupport/src/libio.c b/cpukit/libcsupport/src/libio.c
index e89634f090..22be6411a2 100644
--- a/cpukit/libcsupport/src/libio.c
+++ b/cpukit/libcsupport/src/libio.c
@@ -138,36 +138,8 @@ void rtems_libio_free(
   rtems_libio_lock();
 
     iop->flags = 0;
-    /* If the mapping_refcnt is non-zero, the deferred free will be
-     * called by munmap. The iop is no longer good to use, but it cannot
-     * be recycled until the mapped file is unmapped. deferred free knows
-     * it can recycle the iop in case flags == 0 and iop->data1 == iop,
-     * since these two conditions are not otherwise satisifed at
-     * the same time. It may be possible that iop->data1 == iop when
-     * flags != 0 because data1 is private to the driver. However, flags == 0
-     * means a freed iop, and an iop on the freelist cannot store a pointer
-     * to itself in data1, or else the freelist is corrupted. We can't use
-     * NULL in data1 as an indicator because it is used by the tail of the
-     * freelist. */
-    if ( iop->mapping_refcnt == 0 ) {
-      iop->data1 = rtems_libio_iop_freelist;
-      rtems_libio_iop_freelist = iop;
-    } else {
-      iop->data1 = iop;
-    }
+    iop->data1 = rtems_libio_iop_freelist;
+    rtems_libio_iop_freelist = iop;
 
   rtems_libio_unlock();
 }
-
-void rtems_libio_check_deferred_free(
-  rtems_libio_t *iop
-)
-{
-  rtems_libio_lock();
-    if ( iop->mapping_refcnt == 0 && iop->flags == 0 && iop->data1 == iop) {
-      /* No mappings and rtems_libio_free already called, recycle the iop */
-      iop->data1 = rtems_libio_iop_freelist;
-      rtems_libio_iop_freelist = iop;
-    }
-  rtems_libio_unlock();
-}