Flush dirty cache on close

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1250 42af7a65-404d-4744-a932-0658087f49c3

drivers/bch/Make.defs

@@ -35,6 +35,6 @@
 
 BCH_ASRCS  =
 BCH_CSRCS  = bchlib_setup.c bchlib_teardown.c bchlib_read.c bchlib_write.c \
-             bchlib_cache.c bchlib_refs.c bchlib_sem.c bchdev_register.c \
+             bchlib_cache.c bchlib_sem.c bchdev_register.c bchdev_unregister.c \
-	     bchdev_unregister.c bchdev_driver.c
+	     bchdev_driver.c
 

drivers/bch/bch_internal.h

@@ -88,8 +88,6 @@ EXTERN struct file_operations bch_fops;
  ****************************************************************************/
 
 EXTERN void bchlib_semtake(FAR struct bchlib_s *bch);
-EXTERN int  bchlib_incref(FAR struct bchlib_s *bch);
-EXTERN int  bchlib_decref(FAR struct bchlib_s *bch);
 EXTERN int  bchlib_flushsector(FAR struct bchlib_s *bch);
 EXTERN int  bchlib_readsector(FAR struct bchlib_s *bch, size_t sector);
 

drivers/bch/bchdev_driver.c

@@ -102,9 +102,26 @@ struct file_operations bch_fops =
 static int bch_open(FAR struct file *filp)
 {
   FAR struct inode *inode = filp->f_inode;
+  FAR struct bchlib_s *bch;
+  int ret;
 
   DEBUGASSERT(inode && inode->i_private);
-  return bchlib_incref((FAR struct bchlib_s *)inode->i_private);
+  bch = (FAR struct bchlib_s *)inode->i_private;
+
+  /* Increment the reference count */
+
+  bchlib_semtake(bch);
+  if (bch->refs == MAX_OPENCNT)
+    {
+      return -EMFILE;
+    }
+  else
+    {
+      bch->refs++;
+    }
+  bchlib_semgive(bch);
+
+  return ret;
 }
 
 /****************************************************************************
@@ -117,9 +134,32 @@ static int bch_open(FAR struct file *filp)
 static int bch_close(FAR struct file *filp)
 {
   FAR struct inode *inode = filp->f_inode;
+  FAR struct bchlib_s *bch;
+  int ret;
 
   DEBUGASSERT(inode && inode->i_private);
-  return bchlib_decref((FAR struct bchlib_s *)inode->i_private);
+  bch = (FAR struct bchlib_s *)inode->i_private;
+
+  /* Flush any dirty pages remaining in the cache */
+
+  bchlib_semtake(bch);
+  (void)bchlib_flushsector(bch);
+
+  /* Decrement the reference count (I don't use bchlib_decref() because I
+   * want the entire close operation to be atomic wrt other driver operations.
+   */
+
+  if (bch->refs == 0)
+    {
+      ret = -EIO;
+    }
+  else
+    {
+      bch->refs--;
+    }
+  bchlib_semgive(bch);
+
+  return ret;
 }
 
 /****************************************************************************
@@ -192,15 +232,17 @@ static int bch_ioctl(FAR struct file *filp, int cmd, unsigned long arg)
     {
       FAR struct bchlib_s **bchr = (FAR struct bchlib_s **)arg;
 
-      if (!bchr)
+      bchlib_semtake(bch);
+      if (!bchr && bch->refs < 255)
         {
           ret = -EINVAL;
         }
       else
         {
-          ret = bchlib_incref(bch);
+          bch->refs++;
           *bchr = bch;
         }
+      bchlib_semgive(bch);
     }
 
   return ret;

drivers/bch/bchdev_unregister.c

@@ -111,7 +111,9 @@ int bchdev_unregister(const char *chardev)
       return ret;
     }
 
-  /* Get a reference to the internal data structure */
+  /* Get a reference to the internal data structure.  On success, we
+   * will hold a reference count on the state structure.
+   */
 
   ret = ioctl(fd, DIOC_GETPRIV, (unsigned long)&bch);
   (void)close(fd);
@@ -122,11 +124,14 @@ int bchdev_unregister(const char *chardev)
       return -errno;
     }
 
-  /* Lock out context switches */
+  /* Lock out context switches.  If there are no other references
+   * and no context switches, then we can assume that we can safely
+   * teardown the driver.
+   */
 
   sched_lock();
 
-  /* Check if the internal structure is non-busy (we hold one reference) */
+  /* Check if the internal structure is non-busy (we hold one reference). */
 
   if (bch->refs > 1)
     {
@@ -134,7 +139,10 @@ int bchdev_unregister(const char *chardev)
       goto errout_with_lock;
     }
 
-  /* Unregister the driver (this cannot suspend) */
+  /* Unregister the driver (this cannot suspend or we lose our non-preemptive
+   * state!).  Once the driver is successfully unregistered, we can assume
+   * we have exclusive access to the state instance.
+   */
 
   ret = unregister_driver(chardev);
   if (ret < 0)
@@ -149,7 +157,7 @@ int bchdev_unregister(const char *chardev)
   return bchlib_teardown(bch);
 
 errout_with_lock:
+  bch->refs--;
   sched_unlock();
-  bchlib_decref(bch);
   return ret;
 }

drivers/bch/bchlib_cache.c

@@ -79,6 +79,9 @@
  * Description:
  *   Flush the current contents of the sector buffer (if dirty)
  *
+ * Assumptions:
+ *   Caller must assume mutual exclusion
+ *
  ****************************************************************************/
 
 int bchlib_flushsector(FAR struct bchlib_s *bch)
@@ -105,6 +108,9 @@ int bchlib_flushsector(FAR struct bchlib_s *bch)
  * Description:
  *   Flush the current contents of the sector buffer (if dirty)
  *
+ * Assumptions:
+ *   Caller must assume mutual exclusion
+ *
  ****************************************************************************/
 
 int bchlib_readsector(FAR struct bchlib_s *bch, size_t sector)

drivers/bch/bchlib_refs.c

@@ -1,123 +0,0 @@
-/****************************************************************************
- * drivers/bch/bchlib_refs.c
- *
- *   Copyright (C) 2008 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- *    used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
-
-/****************************************************************************
- * Compilation Switches
- ****************************************************************************/
-
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/config.h>
-
-#include <sys/types.h>
-#if 0
-#include <sys/stat.h>
-#include <sys/ioctl.h>
-
-#include <unistd.h>
-#include <string.h>
-#include <fcntl.h>
-#include <sched.h>
-
-#include <nuttx/fs.h>
-#include <nuttx/ioctl.h>
-#endif
-
-#include <semaphore.h>
-#include <errno.h>
-#include <assert.h>
-#include <debug.h>
-
-#include "bch_internal.h"
-
-/****************************************************************************
- * Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
-
-/****************************************************************************
- * Public Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
-/****************************************************************************
- * Public Functions
- ****************************************************************************/
-
-/****************************************************************************
- * Name: bchlib_incref
- ****************************************************************************/
-
-int bchlib_incref(FAR struct bchlib_s *bch)
-{
-  bchlib_semtake(bch);
-  if (bch->refs == MAX_OPENCNT)
-    {
-      return -EMFILE;
-    }
-  else
-    {
-      bch->refs++;
-    }
-  bchlib_semgive(bch);
-  return OK;
-}
-
-/****************************************************************************
- * Name: bchlib_decref
- ****************************************************************************/
-
-int bchlib_decref(FAR struct bchlib_s *bch)
-{
-  bchlib_semtake(bch);
-  if (bch->refs == 0)
-    {
-      return -EIO;
-    }
-  else
-    {
-      bch->refs--;
-    }
-  bchlib_semgive(bch);
-  return OK;
-}

include/nuttx/fs.h

@@ -392,7 +392,9 @@ EXTERN int loteardown(const char *devname);
 EXTERN int bchdev_register(const char *blkdev, const char *chardev, boolean readonly);
 EXTERN int bchdev_unregister(const char *chardev);
 
-/* Low level, direct access: */
+/* Low level, direct access.  NOTE:  low-level access and character driver access
+ * are incompatible.  One and only one access method should be implemented.
+ */
 
 EXTERN int bchlib_setup(const char *blkdev, boolean readonly, FAR void **handle);
 EXTERN int bchlib_teardown(FAR void *handle);