diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 5cbc4bb..252d15ba 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -170,7 +170,8 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
 	u32 index;		/* device index number */
 	spinlock_t sfd_lock;	/* protect file descriptor list for device */
 	struct list_head sfds;
-	struct rw_semaphore o_sem;	/* exclude open should hold this rwsem */
+	struct semaphore or_sem;  /* protect co-incidental opens and releases */
+	wait_queue_head_t open_wait;	/* waits associated with O_EXCL */
 	volatile char detached;	/* 0->attached, 1->detached pending removal */
 	char exclude;		/* opened for exclusive access */
 	char sgdebug;		/* 0->off, 1->sense, 9->dump dev, 10-> all devs */
@@ -232,6 +233,16 @@ static int sfds_list_empty(Sg_device *sdp)
 }
 
 static int
+open_wait_event(Sg_device *sdp, int excl_case)
+{
+	int retval;
+
+	retval = wait_event_interruptible(sdp->open_wait, (sdp->detached ||
+		    (excl_case ? (!sdp->exclude) : sfds_list_empty(sdp))));
+	return sdp->detached ? -ENODEV : retval;
+}
+
+static int
 sg_open(struct inode *inode, struct file *filp)
 {
 	int dev = iminor(inode);
@@ -239,7 +250,7 @@ sg_open(struct inode *inode, struct file *filp)
 	struct request_queue *q;
 	Sg_device *sdp;
 	Sg_fd *sfp;
-	int retval;
+	int alone, retval;
 
 	nonseekable_open(inode, filp);
 	SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags));
@@ -260,59 +271,81 @@ sg_open(struct inode *inode, struct file *filp)
 	if (retval)
 		goto sdp_put;
 
+	/* scsi_block_when_processing_errors() may block so bypass
+	 * check if O_NONBLOCK. Permits SCSI commands to be issued
+	 * during error recovery. Tread carefully. */
 	if (!((flags & O_NONBLOCK) ||
 	      scsi_block_when_processing_errors(sdp->device))) {
 		retval = -ENXIO;
 		/* we are in error recovery for this device */
-		goto error_out;
+		goto error_upped;
 	}
 
+	down(&sdp->or_sem);
+	alone = sfds_list_empty(sdp);
 	if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE))) {
 		retval = -EPERM; /* Can't lock it with read only access */
 		goto error_out;
 	}
 	if (flags & O_NONBLOCK) {
 		if (flags & O_EXCL) {
-			if (!down_write_trylock(&sdp->o_sem)) {
+			if (!alone) {
 				retval = -EBUSY;
 				goto error_out;
 			}
 		} else {
-			if (!down_read_trylock(&sdp->o_sem)) {
+			if (sdp->exclude) {
 				retval = -EBUSY;
 				goto error_out;
 			}
 		}
 	} else {
-		if (flags & O_EXCL)
-			down_write(&sdp->o_sem);
-		else
-			down_read(&sdp->o_sem);
+		if (flags & O_EXCL) {
+			while (!alone) {
+				up(&sdp->or_sem);
+				retval = open_wait_event(sdp, 0);
+				if (retval) /* -ERESTARTSYS or -ENODEV */
+					goto error_upped;
+				down(&sdp->or_sem);
+				alone = sfds_list_empty(sdp);
+			}
+		} else {
+			while (sdp->exclude) {
+				up(&sdp->or_sem);
+				retval = open_wait_event(sdp, 1);
+				if (retval) /* -ERESTARTSYS or -ENODEV */
+					goto error_upped;
+				down(&sdp->or_sem);
+				alone = sfds_list_empty(sdp);
+			}
+		}
 	}
 	/* Since write lock is held, no need to check sfd_list */
 	if (flags & O_EXCL)
 		sdp->exclude = 1;	/* used by release lock */
 
-	if (sfds_list_empty(sdp)) {	/* no existing opens on this device */
+	if (alone) {	/* no existing opens on this device */
 		sdp->sgdebug = 0;
 		q = sdp->device->request_queue;
 		sdp->sg_tablesize = queue_max_segments(q);
 	}
 	sfp = sg_add_sfp(sdp, dev);
-	if (!IS_ERR(sfp))
+	if (!IS_ERR(sfp)) {
 		filp->private_data = sfp;
 		/* retval is already provably zero at this point because of the
 		 * check after retval = scsi_autopm_get_device(sdp->device))
 		 */
-	else {
+		up(&sdp->or_sem);
+	} else {
 		retval = PTR_ERR(sfp);
 
 		if (flags & O_EXCL) {
 			sdp->exclude = 0;	/* undo if error */
-			up_write(&sdp->o_sem);
-		} else
-			up_read(&sdp->o_sem);
+			wake_up_interruptible(&sdp->open_wait);
+		}
 error_out:
+		up(&sdp->or_sem);
+error_upped:
 		scsi_autopm_put_device(sdp->device);
 sdp_put:
 		scsi_device_put(sdp->device);
@@ -333,17 +366,18 @@ sg_release(struct inode *inode, struct file *filp)
 
 	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
 		return -ENXIO;
+	down(&sdp->or_sem);
 	SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
 
 	excl = sdp->exclude;
-	sdp->exclude = 0;
 	if (excl)
-		up_write(&sdp->o_sem);
-	else
-		up_read(&sdp->o_sem);
+		sdp->exclude = 0;
 
 	scsi_autopm_put_device(sdp->device);
 	kref_put(&sfp->f_ref, sg_remove_sfp);
+	if (excl || sfds_list_empty(sdp))
+		wake_up_interruptible(&sdp->open_wait);
+	up(&sdp->or_sem);
 	return 0;
 }
 
@@ -1393,7 +1427,8 @@ static Sg_device *sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
 	sdp->device = scsidp;
 	spin_lock_init(&sdp->sfd_lock);
 	INIT_LIST_HEAD(&sdp->sfds);
-	init_rwsem(&sdp->o_sem);
+	sema_init(&sdp->or_sem, 1);
+	init_waitqueue_head(&sdp->open_wait);
 	sdp->sg_tablesize = queue_max_segments(q);
 	sdp->index = k;
 	kref_init(&sdp->d_ref);