libio: Add hold/drop iop reference

Check iop reference count in close() and return -1 with errno set to
EBUSY in case the file descriptor is still in use.

Update #3132.

19 files changed, 141 insertions, 44 deletions

diff --git a/cpukit/libcsupport/include/rtems/libio.h b/cpukit/libcsupport/include/rtems/libio.h
index 2a67496800..804929915a 100644
--- a/cpukit/libcsupport/include/rtems/libio.h
+++ b/cpukit/libcsupport/include/rtems/libio.h
@@ -37,6 +37,7 @@
 #include <rtems.h>
 #include <rtems/fs.h>
 #include <rtems/chain.h>
+#include <rtems/score/atomic.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -1319,7 +1320,7 @@ extern const rtems_filesystem_limits_and_options_t
 struct rtems_libio_tt {
   rtems_driver_name_t                    *driver;
   off_t                                   offset;    /* current offset into file */
-  uint32_t                                flags;
+  Atomic_Uint                             flags;
   rtems_filesystem_location_info_t        pathinfo;
   uint32_t                                data0;     /* private to "driver" */
   void                                   *data1;     /* ... */
@@ -1371,12 +1372,13 @@ typedef struct {
 #define LIBIO_FLAGS_APPEND        0x0200U  /* all writes append */
 #define LIBIO_FLAGS_CLOSE_ON_EXEC 0x0800U  /* close on process exec() */
 #define LIBIO_FLAGS_READ_WRITE    (LIBIO_FLAGS_READ | LIBIO_FLAGS_WRITE)
+#define LIBIO_FLAGS_REFERENCE_INC 0x1000U
 
 /** @} */
 
-static inline uint32_t rtems_libio_iop_flags( const rtems_libio_t *iop )
+static inline unsigned int rtems_libio_iop_flags( const rtems_libio_t *iop )
 {
-  return iop->flags;
+  return _Atomic_Load_uint( &iop->flags, ATOMIC_ORDER_RELAXED );
 }
 
 /**
diff --git a/cpukit/libcsupport/include/rtems/libio_.h b/cpukit/libcsupport/include/rtems/libio_.h
index adf137d2f6..dc1fe9808a 100644
--- a/cpukit/libcsupport/include/rtems/libio_.h
+++ b/cpukit/libcsupport/include/rtems/libio_.h
@@ -104,7 +104,11 @@ static inline void rtems_libio_iop_flags_initialize(
   uint32_t       flags
 )
 {
-  iop->flags = LIBIO_FLAGS_OPEN | flags;
+  _Atomic_Store_uint(
+    &iop->flags,
+    LIBIO_FLAGS_OPEN | flags,
+    ATOMIC_ORDER_RELEASE
+  );
 }
 
 /**
@@ -115,16 +119,12 @@ static inline void rtems_libio_iop_flags_initialize(
  *
  * @return The previous flags.
  */
-static inline uint32_t rtems_libio_iop_flags_set(
+static inline unsigned int rtems_libio_iop_flags_set(
   rtems_libio_t *iop,
-  uint32_t       set
+  unsigned int   set
 )
 {
-  uint32_t flags;
-
-  flags = iop->flags;
-  iop->flags = flags | set;
-  return flags;
+  return _Atomic_Fetch_or_uint( &iop->flags, set, ATOMIC_ORDER_RELAXED );
 }
 
 /**
@@ -135,16 +135,12 @@ static inline uint32_t rtems_libio_iop_flags_set(
  *
  * @return The previous flags.
  */
-static inline uint32_t rtems_libio_iop_flags_clear(
+static inline unsigned int rtems_libio_iop_flags_clear(
   rtems_libio_t *iop,
-  uint32_t       clear
+  unsigned int   clear
 )
 {
-  uint32_t flags;
-
-  flags = iop->flags;
-  iop->flags = flags & ~clear;
-  return flags;
+  return _Atomic_Fetch_and_uint( &iop->flags, ~clear, ATOMIC_ORDER_RELAXED );
 }
 
 /**
@@ -161,6 +157,36 @@ static inline rtems_libio_t *rtems_libio_iop( int fd )
   return &rtems_libio_iops[ fd ];
 }
 
+/**
+ * @brief Holds a refernece to the iop.
+ *
+ * @param[in] iop The iop.
+ *
+ * @return The flags corresponding to the specified iop.
+ */
+static inline unsigned int rtems_libio_iop_hold( rtems_libio_t *iop )
+{
+  return _Atomic_Fetch_add_uint(
+    &iop->flags,
+    LIBIO_FLAGS_REFERENCE_INC,
+    ATOMIC_ORDER_ACQUIRE
+  );
+}
+
+/**
+ * @brief Drops a refernece to the iop.
+ *
+ * @param[in] iop The iop.
+ */
+static inline void rtems_libio_iop_drop( rtems_libio_t *iop )
+{
+  _Atomic_Fetch_sub_uint(
+    &iop->flags,
+    LIBIO_FLAGS_REFERENCE_INC,
+    ATOMIC_ORDER_RELEASE
+  );
+}
+
 /*
  *  rtems_libio_iop_to_descriptor
  *
@@ -192,13 +218,14 @@ static inline rtems_libio_t *rtems_libio_iop( int fd )
  */
 #define LIBIO_GET_IOP( _fd, _iop ) \
   do { \
-    uint32_t _flags; \
+    unsigned int _flags; \
     if ( (uint32_t) ( _fd ) >= rtems_libio_number_iops ) { \
       rtems_set_errno_and_return_minus_one( EBADF ); \
     } \
     _iop = rtems_libio_iop( _fd ); \
-    _flags = _iop->flags; \
+    _flags = rtems_libio_iop_hold( _iop ); \
     if ( ( _flags & LIBIO_FLAGS_OPEN ) == 0 ) { \
+      rtems_libio_iop_drop( _iop ); \
       rtems_set_errno_and_return_minus_one( EBADF ); \
     } \
   } while ( 0 )
@@ -211,16 +238,17 @@ static inline rtems_libio_t *rtems_libio_iop( int fd )
  */
 #define LIBIO_GET_IOP_WITH_ACCESS( _fd, _iop, _access_flags, _access_error ) \
   do { \
-    uint32_t _flags; \
-    uint32_t _mandatory; \
+    unsigned int _flags; \
+    unsigned int _mandatory; \
     if ( (uint32_t) ( _fd ) >= rtems_libio_number_iops ) { \
       rtems_set_errno_and_return_minus_one( EBADF ); \
     } \
     _iop = rtems_libio_iop( _fd ); \
-    _flags = _iop->flags; \
+    _flags = rtems_libio_iop_hold( _iop ); \
     _mandatory = LIBIO_FLAGS_OPEN | ( _access_flags ); \
     if ( ( _flags & _mandatory ) != _mandatory ) { \
       int _error; \
+      rtems_libio_iop_drop( _iop ); \
       if ( ( _flags & LIBIO_FLAGS_OPEN ) == 0 ) { \
         _error = EBADF; \
       } else { \
@@ -357,12 +385,12 @@ rtems_libio_t *rtems_libio_allocate(void);
 /**
  * Convert UNIX fnctl(2) flags to ones that RTEMS drivers understand
  */
-uint32_t rtems_libio_fcntl_flags( int fcntl_flags );
+unsigned int rtems_libio_fcntl_flags( int fcntl_flags );
 
 /**
  * Convert RTEMS internal flags to UNIX fnctl(2) flags
  */
-int rtems_libio_to_fcntl_flags( uint32_t flags );
+int rtems_libio_to_fcntl_flags( unsigned int flags );
 
 /**
  * This routine frees the resources associated with an IOP (file descriptor)
@@ -932,7 +960,7 @@ static inline ssize_t rtems_libio_iovec_eval(
   int                        fd,
   const struct iovec        *iov,
   int                        iovcnt,
-  uint32_t                   flags,
+  unsigned int               flags,
   rtems_libio_iovec_adapter  adapter
 )
 {
@@ -978,6 +1006,7 @@ static inline ssize_t rtems_libio_iovec_eval(
     total = ( *adapter )( iop, iov, iovcnt, total );
   }
 
+  rtems_libio_iop_drop( iop );
   return total;
 }
 
diff --git a/cpukit/libcsupport/src/close.c b/cpukit/libcsupport/src/close.c
index 7eaeb64fea..d478e231c6 100644
--- a/cpukit/libcsupport/src/close.c
+++ b/cpukit/libcsupport/src/close.c
@@ -24,12 +24,45 @@ int close(
   int  fd
 )
 {
-  rtems_libio_t      *iop;
-  int                 rc;
+  rtems_libio_t *iop;
+  unsigned int   flags;
+  int            rc;
 
-  LIBIO_GET_IOP( fd, iop );
+  if ( (uint32_t) fd >= rtems_libio_number_iops ) {
+    rtems_set_errno_and_return_minus_one( EBADF );
+  }
 
-  rtems_libio_iop_flags_clear( iop, LIBIO_FLAGS_OPEN );
+  iop = rtems_libio_iop( fd );
+  flags = rtems_libio_iop_flags( iop );
+
+  while ( true ) {
+    unsigned int desired;
+    bool         success;
+
+    if ( ( flags & LIBIO_FLAGS_OPEN ) == 0 ) {
+      rtems_set_errno_and_return_minus_one( EBADF );
+    }
+
+    /* The expected flags */
+    flags &= LIBIO_FLAGS_REFERENCE_INC - 1U;
+
+    desired = flags & ~LIBIO_FLAGS_OPEN;
+    success = _Atomic_Compare_exchange_uint(
+      &iop->flags,
+      &flags,
+      desired,
+      ATOMIC_ORDER_ACQ_REL,
+      ATOMIC_ORDER_RELAXED
+    );
+
+    if ( success ) {
+      break;
+    }
+
+    if ( ( flags & ~( LIBIO_FLAGS_REFERENCE_INC - 1U ) ) != 0 ) {
+      rtems_set_errno_and_return_minus_one( EBUSY );
+    }
+  }
 
   rc = (*iop->pathinfo.handlers->close_h)( iop );
 
diff --git a/cpukit/libcsupport/src/fchdir.c b/cpukit/libcsupport/src/fchdir.c
index ece73ab3ec..df37458ead 100644
--- a/cpukit/libcsupport/src/fchdir.c
+++ b/cpukit/libcsupport/src/fchdir.c
@@ -59,6 +59,7 @@ int fchdir( int fd )
     }
   }
   rtems_filesystem_instance_unlock( &iop->pathinfo );
+  rtems_libio_iop_drop( iop );
 
   if ( rv == 0 ) {
     rv = rtems_filesystem_chdir( &loc );
diff --git a/cpukit/libcsupport/src/fchmod.c b/cpukit/libcsupport/src/fchmod.c
index 126b015501..13e7fdd380 100644
--- a/cpukit/libcsupport/src/fchmod.c
+++ b/cpukit/libcsupport/src/fchmod.c
@@ -75,5 +75,7 @@ int fchmod( int fd, mode_t mode )
 
   rtems_filesystem_instance_unlock( &iop->pathinfo );
 
+  rtems_libio_iop_drop( iop );
+
   return rv;
 }
diff --git a/cpukit/libcsupport/src/fchown.c b/cpukit/libcsupport/src/fchown.c
index bd787d89e3..8c3d9b2c6c 100644
--- a/cpukit/libcsupport/src/fchown.c
+++ b/cpukit/libcsupport/src/fchown.c
@@ -72,5 +72,7 @@ int fchown( int fd, uid_t owner, gid_t group )
 
   rtems_filesystem_instance_unlock( &iop->pathinfo );
 
+  rtems_libio_iop_drop( iop );
+
   return rv;
 }
diff --git a/cpukit/libcsupport/src/fcntl.c b/cpukit/libcsupport/src/fcntl.c
index a7fcfbc041..ddbf5538f9 100644
--- a/cpukit/libcsupport/src/fcntl.c
+++ b/cpukit/libcsupport/src/fcntl.c
@@ -213,6 +213,8 @@ static int vfcntl(
       ret = -1;
     }
   }
+
+  rtems_libio_iop_drop( iop );
   return ret;
 }
 
diff --git a/cpukit/libcsupport/src/fdatasync.c b/cpukit/libcsupport/src/fdatasync.c
index 14e66726e6..bf90957f0f 100644
--- a/cpukit/libcsupport/src/fdatasync.c
+++ b/cpukit/libcsupport/src/fdatasync.c
@@ -28,6 +28,7 @@ int fdatasync(
 )
 {
   rtems_libio_t *iop;
+  int            rv;
 
   LIBIO_GET_IOP_WITH_ACCESS( fd, iop, LIBIO_FLAGS_WRITE, EBADF );
 
@@ -35,5 +36,7 @@ int fdatasync(
    *  Now process the fdatasync().
    */
 
-  return (*iop->pathinfo.handlers->fdatasync_h)( iop );
+  rv = (*iop->pathinfo.handlers->fdatasync_h)( iop );
+  rtems_libio_iop_drop( iop );
+  return rv;
 }
diff --git a/cpukit/libcsupport/src/fpathconf.c b/cpukit/libcsupport/src/fpathconf.c
index db323136c7..d08ac9c776 100644
--- a/cpukit/libcsupport/src/fpathconf.c
+++ b/cpukit/libcsupport/src/fpathconf.c
@@ -82,9 +82,11 @@ long fpathconf(
       return_value = the_limits->posix_sync_io;
       break;
     default:
-      rtems_set_errno_and_return_minus_one( EINVAL );
+      errno = EINVAL;
+      return_value = -1;
       break;
   }
 
+  rtems_libio_iop_drop( iop );
   return return_value;
 }
diff --git a/cpukit/libcsupport/src/fstat.c b/cpukit/libcsupport/src/fstat.c
index 4a10d166bd..3a1241a862 100644
--- a/cpukit/libcsupport/src/fstat.c
+++ b/cpukit/libcsupport/src/fstat.c
@@ -26,6 +26,7 @@ int fstat(
 )
 {
   rtems_libio_t *iop;
+  int            rv;
 
   /*
    *  Check to see if we were passed a valid pointer.
@@ -44,7 +45,9 @@ int fstat(
    */
   memset( sbuf, 0, sizeof(struct stat) );
 
-  return (*iop->pathinfo.handlers->fstat_h)( &iop->pathinfo, sbuf );
+  rv = (*iop->pathinfo.handlers->fstat_h)( &iop->pathinfo, sbuf );
+  rtems_libio_iop_drop( iop );
+  return rv;
 }
 
 /*
diff --git a/cpukit/libcsupport/src/fsync.c b/cpukit/libcsupport/src/fsync.c
index 6332180721..428f82abd0 100644
--- a/cpukit/libcsupport/src/fsync.c
+++ b/cpukit/libcsupport/src/fsync.c
@@ -31,6 +31,7 @@ int fsync(
 )
 {
   rtems_libio_t *iop;
+  int            rv;
 
   LIBIO_GET_IOP( fd, iop );
 
@@ -38,5 +39,7 @@ int fsync(
    *  Now process the fsync().
    */
 
-  return (*iop->pathinfo.handlers->fsync_h)( iop );
+  rv = (*iop->pathinfo.handlers->fsync_h)( iop );
+  rtems_libio_iop_drop( iop );
+  return rv;
 }
diff --git a/cpukit/libcsupport/src/ftruncate.c b/cpukit/libcsupport/src/ftruncate.c
index 401510b2ff..99a9c6b5ef 100644
--- a/cpukit/libcsupport/src/ftruncate.c
+++ b/cpukit/libcsupport/src/ftruncate.c
@@ -32,6 +32,7 @@ int ftruncate( int fd, off_t length )
     LIBIO_GET_IOP_WITH_ACCESS( fd, iop, LIBIO_FLAGS_WRITE, EINVAL );
 
     rv = (*iop->pathinfo.handlers->ftruncate_h)( iop, length );
+    rtems_libio_iop_drop( iop );
   } else {
     errno = EINVAL;
     rv = -1;
diff --git a/cpukit/libcsupport/src/ioctl.c b/cpukit/libcsupport/src/ioctl.c
index 9fa7fa15a2..b2be524075 100644
--- a/cpukit/libcsupport/src/ioctl.c
+++ b/cpukit/libcsupport/src/ioctl.c
@@ -51,5 +51,6 @@ int ioctl(
   rc = (*iop->pathinfo.handlers->ioctl_h)( iop, command, buffer );
 
   va_end( ap );
+  rtems_libio_iop_drop( iop );
   return rc;
 }
diff --git a/cpukit/libcsupport/src/libio.c b/cpukit/libcsupport/src/libio.c
index 0cc2b98c0b..26fa7b2f67 100644
--- a/cpukit/libcsupport/src/libio.c
+++ b/cpukit/libcsupport/src/libio.c
@@ -58,16 +58,16 @@ static const rtems_assoc_t status_flags_assoc[] = {
   { 0, 0, 0 },
 };
 
-uint32_t rtems_libio_fcntl_flags( int fcntl_flags )
+unsigned int rtems_libio_fcntl_flags( int fcntl_flags )
 {
-  uint32_t   flags = 0;
+  unsigned int   flags = 0;
   uint32_t   access_modes;
 
   /*
    * Access mode is a small integer
    */
 
-  access_modes = (uint32_t) (fcntl_flags & O_ACCMODE);
+  access_modes = (unsigned int) (fcntl_flags & O_ACCMODE);
   fcntl_flags &= ~O_ACCMODE;
   flags = rtems_assoc_local_by_remote( access_modes_assoc, access_modes );
 
@@ -75,7 +75,7 @@ uint32_t rtems_libio_fcntl_flags( int fcntl_flags )
    * Everything else is single bits
    */
 
-  flags |= rtems_assoc_local_by_remote_bitfield(
+  flags |= (unsigned int ) rtems_assoc_local_by_remote_bitfield(
     status_flags_assoc,
     (uint32_t) fcntl_flags
   );
@@ -83,7 +83,7 @@ uint32_t rtems_libio_fcntl_flags( int fcntl_flags )
   return flags;
 }
 
-int rtems_libio_to_fcntl_flags( uint32_t flags )
+int rtems_libio_to_fcntl_flags( unsigned int flags )
 {
   int fcntl_flags = 0;
 
diff --git a/cpukit/libcsupport/src/lseek.c b/cpukit/libcsupport/src/lseek.c
index 16271eba09..00307e3e0d 100644
--- a/cpukit/libcsupport/src/lseek.c
+++ b/cpukit/libcsupport/src/lseek.c
@@ -20,10 +20,13 @@
 off_t lseek( int fd, off_t offset, int whence )
 {
   rtems_libio_t *iop;
+  off_t          rv;
 
   LIBIO_GET_IOP( fd, iop );
 
-  return (*iop->pathinfo.handlers->lseek_h)( iop, offset, whence );
+  rv = (*iop->pathinfo.handlers->lseek_h)( iop, offset, whence );
+  rtems_libio_iop_drop( iop );
+  return rv;
 }
 
 /*
diff --git a/cpukit/libcsupport/src/open.c b/cpukit/libcsupport/src/open.c
index 22773454ba..8558e207d3 100644
--- a/cpukit/libcsupport/src/open.c
+++ b/cpukit/libcsupport/src/open.c
@@ -99,7 +99,11 @@ static int do_open(
   rtems_filesystem_eval_path_extract_currentloc( &ctx, &iop->pathinfo );
   rtems_filesystem_eval_path_cleanup( &ctx );
 
-  iop->flags = rtems_libio_fcntl_flags( oflag );
+  _Atomic_Store_uint(
+    &iop->flags,
+    rtems_libio_fcntl_flags( oflag ),
+    ATOMIC_ORDER_RELAXED
+  );
 
   rv = (*iop->pathinfo.handlers->open_h)( iop, path, oflag, mode );
 
diff --git a/cpukit/libcsupport/src/read.c b/cpukit/libcsupport/src/read.c
index d55ff180ae..03c39120bb 100644
--- a/cpukit/libcsupport/src/read.c
+++ b/cpukit/libcsupport/src/read.c
@@ -31,6 +31,7 @@ ssize_t read(
 )
 {
   rtems_libio_t *iop;
+  ssize_t        n;
 
   rtems_libio_check_buffer( buffer );
   rtems_libio_check_count( count );
@@ -40,7 +41,9 @@ ssize_t read(
   /*
    *  Now process the read().
    */
-  return (*iop->pathinfo.handlers->read_h)( iop, buffer, count );
+  n = (*iop->pathinfo.handlers->read_h)( iop, buffer, count );
+  rtems_libio_iop_drop( iop );
+  return n;
 }
 
 #if defined(RTEMS_NEWLIB) && !defined(HAVE__READ_R)
diff --git a/cpukit/libcsupport/src/write.c b/cpukit/libcsupport/src/write.c
index f44962afd8..a90b291ed8 100644
--- a/cpukit/libcsupport/src/write.c
+++ b/cpukit/libcsupport/src/write.c
@@ -34,6 +34,7 @@ ssize_t write(
 )
 {
   rtems_libio_t *iop;
+  ssize_t        n;
 
   rtems_libio_check_buffer( buffer );
   rtems_libio_check_count( count );
@@ -43,5 +44,7 @@ ssize_t write(
   /*
    *  Now process the write() request.
    */
-  return (*iop->pathinfo.handlers->write_h)( iop, buffer, count );
+  n = (*iop->pathinfo.handlers->write_h)( iop, buffer, count );
+  rtems_libio_iop_drop( iop );
+  return n;
 }
diff --git a/cpukit/posix/src/shmopen.c b/cpukit/posix/src/shmopen.c
index f6c9f58cb4..59e9e9da22 100644
--- a/cpukit/posix/src/shmopen.c
+++ b/cpukit/posix/src/shmopen.c
@@ -225,7 +225,7 @@ int shm_open( const char *name, int oflag, mode_t mode )
   POSIX_Shm_Control *shm;
   size_t len;
   Objects_Get_by_name_error obj_err;
-  uint32_t flags;
+  unsigned int flags;
 
   if ( shm_check_oflag( oflag ) != 0 ) {
     return -1;