change sdev.access_count to an atomic_t

diff -Nru a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
@@ -889,21 +889,24 @@
 int scsi_device_get(struct scsi_device *sdev)
 {
 	struct class *class = class_get(&sdev_class);
-	int error = -ENXIO;
 
-	if (class) {
-		down_write(&class->subsys.rwsem);
-		if (!test_bit(SDEV_DEL, &sdev->sdev_state))
-			if (try_module_get(sdev->host->hostt->module)) 
-				if (get_device(&sdev->sdev_gendev)) {
-					sdev->access_count++;
-					error = 0;
-				}
-		up_write(&class->subsys.rwsem);
-		class_put(&sdev_class);
-	}
+	if (!class)
+		goto out;
+	if (test_bit(SDEV_DEL, &sdev->sdev_state))
+		goto out;
+	if (!try_module_get(sdev->host->hostt->module))
+		goto out;
+	if (!get_device(&sdev->sdev_gendev))
+		goto out_put_module;
+	atomic_inc(&sdev->access_count);
+	class_put(&sdev_class);
+	return 0;
 
-	return error;
+ out_put_module:
+	module_put(sdev->host->hostt->module);
+ out:
+	class_put(&sdev_class);
+	return -ENXIO;
 }
 
 void scsi_device_put(struct scsi_device *sdev)

@@ -913,15 +916,11 @@
 	if (!class)
 		return;
 
-	down_write(&class->subsys.rwsem);
 	module_put(sdev->host->hostt->module);
-	if (--sdev->access_count == 0) {
+	if (atomic_dec_and_test(&sdev->access_count))
 		if (test_bit(SDEV_DEL, &sdev->sdev_state))
 			device_del(&sdev->sdev_gendev);
-	}
 	put_device(&sdev->sdev_gendev);
-	up_write(&class->subsys.rwsem);
-
 	class_put(&sdev_class);
 }
 

diff -Nru a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
@@ -216,7 +216,7 @@
 	sdev = scsi_find_device(shost, channel, id, lun);
 	if (!sdev)
 		goto out;
-	if (sdev->access_count)
+	if (atomic_read(&sdev->access_count))
 		goto out;
 
 	scsi_remove_device(sdev);

diff -Nru a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
@@ -203,6 +203,7 @@
 		goto out;
 
 	memset(sdev, 0, sizeof(*sdev));
+	atomic_set(&sdev->access_count, 0);
 	sdev->vendor = scsi_null_device_strs;
 	sdev->model = scsi_null_device_strs;
 	sdev->rev = scsi_null_device_strs;

diff -Nru a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
@@ -246,7 +246,6 @@
 sdev_rd_attr (queue_depth, "%d\n");
 sdev_rd_attr (type, "%d\n");
 sdev_rd_attr (scsi_level, "%d\n");
-sdev_rd_attr (access_count, "%d\n");
 sdev_rd_attr (vendor, "%.8s\n");
 sdev_rd_attr (model, "%.16s\n");
 sdev_rd_attr (rev, "%.4s\n");

@@ -265,17 +264,14 @@
 				 size_t count)
 {
 	struct scsi_device *sdev = to_scsi_device(dev);
-	int res = count;
 
-	if (sdev->access_count)
-		/*
-		 * FIXME and scsi_proc.c: racey use of access_count,
-		 * possibly add a new arg to scsi_remove_device.
-		 */
-		res = -EBUSY;
-	else
-		scsi_remove_device(sdev);
-	return res;
+	/*
+	 * FIXME and scsi_proc.c: racey use of access_count,
+	 */
+	if (atomic_read(&sdev->access_count))
+		return -EBUSY;
+	scsi_remove_device(sdev);
+	return count;
 };
 static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
 

@@ -285,7 +281,6 @@
 	&dev_attr_queue_depth,
 	&dev_attr_type,
 	&dev_attr_scsi_level,
-	&dev_attr_access_count,
 	&dev_attr_vendor,
 	&dev_attr_model,
 	&dev_attr_rev,

@@ -415,7 +410,7 @@
 	if (class) {
 		down_write(&class->subsys.rwsem);
 		set_bit(SDEV_DEL, &sdev->sdev_state);
-		if (sdev->access_count == 0)
+		if (atomic_read(&sdev->access_count))
 			device_del(&sdev->sdev_gendev);
 		up_write(&class->subsys.rwsem);
 	}

diff -Nru a/drivers/scsi/sg.c b/drivers/scsi/sg.c
@@ -912,7 +912,7 @@
 	case SG_GET_VERSION_NUM:
 		return put_user(sg_version_num, (int *) arg);
 	case SG_GET_ACCESS_COUNT:
-		val = (sdp->device ? sdp->device->access_count : 0);
+		val = (sdp->device ? atomic_read(&sdp->device->access_count) : 0);
 		return put_user(val, (int *) arg);
 	case SG_GET_REQUEST_TABLE:
 		result = verify_area(VERIFY_WRITE, (void *) arg,

@@ -2899,7 +2899,7 @@
 			PRINT_PROC("%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\t%d\n",
 				   scsidp->host->host_no, scsidp->channel,
 				   scsidp->id, scsidp->lun, (int) scsidp->type,
-				   (int) scsidp->access_count,
+				   (int) atomic_read(&scsidp->access_count),
 				   (int) scsidp->queue_depth,
 				   (int) scsidp->device_busy,
 				   (int) scsidp->online);

diff -Nru a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
@@ -4,6 +4,7 @@
 #include <linux/device.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
+#include <asm/atomic.h>
 
 struct request_queue;
 struct scsi_cmnd;

@@ -44,7 +45,7 @@
 					 * vendor-specific cmd's */
 	unsigned sector_size;	/* size in bytes */
 
-	int access_count;	/* Count of open channels/mounts */
+	atomic_t access_count;	/* Count of open channels/mounts */
 
 	void *hostdata;		/* available to low-level driver */
 	char devfs_name[256];	/* devfs junk */