USB: g_mass_storage: most data moved to fsg_common

Most of the data from fsg_dev have been moved to fsg_common
structure.  The fsg_dev structure holds only endpoint dependent
data.  The fsg_common structure has a fsg pointer which points
to active fsg_dev structure -- endpoints are referenced via this
pointer.

This fixes the problem of several threads created when a single
instance of MSF is used in several USB configurations.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 648 insertions, 582 deletions

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index 5eaf22db7fc..a6cec37768a 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -312,14 +312,26 @@ static const char fsg_string_interface[] = "Mass Storage";
 
 /*-------------------------------------------------------------------------*/
 
+struct fsg_dev;
+
 
 /* Data shared by all the FSG instances. */
 struct fsg_common {
 	struct usb_gadget	*gadget;
+	struct fsg_dev		*fsg;
+	struct fsg_dev		*prev_fsg;
 
 	/* filesem protects: backing files in use */
 	struct rw_semaphore	filesem;
 
+	/* lock protects: state, all the req_busy's */
+	spinlock_t		lock;
+
+	struct usb_ep		*ep0;		/* Copy of gadget->ep0 */
+	struct usb_request	*ep0req;	/* Copy of cdev->req */
+	unsigned int		ep0_req_tag;
+	const char		*ep0req_name;
+
 	struct fsg_buffhd	*next_buffhd_to_fill;
 	struct fsg_buffhd	*next_buffhd_to_drain;
 	struct fsg_buffhd	buffhds[FSG_NUM_BUFFERS];
@@ -332,10 +344,28 @@ struct fsg_common {
 	struct fsg_lun		*luns;
 	struct fsg_lun		*curlun;
 
+	unsigned int		bulk_out_maxpacket;
+	enum fsg_state		state;		/* For exception handling */
+	unsigned int		exception_req_tag;
+
+	u8			config, new_config;
+	enum data_direction	data_dir;
+	u32			data_size;
+	u32			data_size_from_cmnd;
+	u32			tag;
+	u32			residue;
+	u32			usb_amount_left;
+
 	unsigned int		can_stall:1;
 	unsigned int		free_storage_on_release:1;
+	unsigned int		phase_error:1;
+	unsigned int		short_packet_received:1;
+	unsigned int		bad_lun_okay:1;
+	unsigned int		running:1;
 
-	const char		*thread_name;
+	int			thread_wakeup_needed;
+	struct completion	thread_notifier;
+	struct task_struct	*thread_task;
 
 	/* Vendor (8 chars), product (16 chars), release (4
 	 * hexadecimal digits) and NUL byte */
@@ -367,52 +397,32 @@ struct fsg_config {
 
 struct fsg_dev {
 	struct usb_function	function;
-	struct usb_composite_dev *cdev;
 	struct usb_gadget	*gadget;	/* Copy of cdev->gadget */
 	struct fsg_common	*common;
 
 	u16			interface_number;
 
-	/* lock protects: state, all the req_busy's */
-	spinlock_t		lock;
-
-	struct usb_ep		*ep0;		/* Copy of gadget->ep0 */
-	struct usb_request	*ep0req;	/* Copy of cdev->req */
-	unsigned int		ep0_req_tag;
-	const char		*ep0req_name;
-
-	unsigned int		bulk_out_maxpacket;
-	enum fsg_state		state;		/* For exception handling */
-	unsigned int		exception_req_tag;
-
-	u8			config, new_config;
-
-	unsigned int		running:1;
 	unsigned int		bulk_in_enabled:1;
 	unsigned int		bulk_out_enabled:1;
-	unsigned int		phase_error:1;
-	unsigned int		short_packet_received:1;
-	unsigned int		bad_lun_okay:1;
-	unsigned int		can_stall:1;
 
 	unsigned long		atomic_bitflags;
-#define REGISTERED		0
-#define IGNORE_BULK_OUT		1
+#define IGNORE_BULK_OUT		0
 
 	struct usb_ep		*bulk_in;
 	struct usb_ep		*bulk_out;
+};
 
-	int			thread_wakeup_needed;
-	struct completion	thread_notifier;
-	struct task_struct	*thread_task;
 
-	enum data_direction	data_dir;
-	u32			data_size;
-	u32			data_size_from_cmnd;
-	u32			tag;
-	u32			residue;
-	u32			usb_amount_left;
-};
+static inline int __fsg_is_set(struct fsg_common *common,
+			       const char *func, unsigned line)
+{
+	if (common->fsg)
+		return 1;
+	ERROR(common, "common->fsg is NULL in %s at %u\n", func, line);
+	return 0;
+}
+
+#define fsg_is_set(common) likely(__fsg_is_set(common, __func__, __LINE__))
 
 
 static inline struct fsg_dev *fsg_from_func(struct usb_function *f)
@@ -423,21 +433,21 @@ static inline struct fsg_dev *fsg_from_func(struct usb_function *f)
 
 typedef void (*fsg_routine_t)(struct fsg_dev *);
 
-static int exception_in_progress(struct fsg_dev *fsg)
+static int exception_in_progress(struct fsg_common *common)
 {
-	return (fsg->state > FSG_STATE_IDLE);
+	return common->state > FSG_STATE_IDLE;
 }
 
 /* Make bulk-out requests be divisible by the maxpacket size */
-static void set_bulk_out_req_length(struct fsg_dev *fsg,
+static void set_bulk_out_req_length(struct fsg_common *common,
 		struct fsg_buffhd *bh, unsigned int length)
 {
 	unsigned int	rem;
 
 	bh->bulk_out_intended_length = length;
-	rem = length % fsg->bulk_out_maxpacket;
+	rem = length % common->bulk_out_maxpacket;
 	if (rem > 0)
-		length += fsg->bulk_out_maxpacket - rem;
+		length += common->bulk_out_maxpacket - rem;
 	bh->outreq->length = length;
 }
 
@@ -463,47 +473,46 @@ static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
 /* These routines may be called in process context or in_irq */
 
 /* Caller must hold fsg->lock */
-static void wakeup_thread(struct fsg_dev *fsg)
+static void wakeup_thread(struct fsg_common *common)
 {
 	/* Tell the main thread that something has happened */
-	fsg->thread_wakeup_needed = 1;
-	if (fsg->thread_task)
-		wake_up_process(fsg->thread_task);
+	common->thread_wakeup_needed = 1;
+	if (common->thread_task)
+		wake_up_process(common->thread_task);
 }
 
 
-static void raise_exception(struct fsg_dev *fsg, enum fsg_state new_state)
+static void raise_exception(struct fsg_common *common, enum fsg_state new_state)
 {
 	unsigned long		flags;
 
 	/* Do nothing if a higher-priority exception is already in progress.
 	 * If a lower-or-equal priority exception is in progress, preempt it
 	 * and notify the main thread by sending it a signal. */
-	spin_lock_irqsave(&fsg->lock, flags);
-	if (fsg->state <= new_state) {
-		fsg->exception_req_tag = fsg->ep0_req_tag;
-		fsg->state = new_state;
-		if (fsg->thread_task)
+	spin_lock_irqsave(&common->lock, flags);
+	if (common->state <= new_state) {
+		common->exception_req_tag = common->ep0_req_tag;
+		common->state = new_state;
+		if (common->thread_task)
 			send_sig_info(SIGUSR1, SEND_SIG_FORCED,
-					fsg->thread_task);
+				      common->thread_task);
 	}
-	spin_unlock_irqrestore(&fsg->lock, flags);
+	spin_unlock_irqrestore(&common->lock, flags);
 }
 
 
 /*-------------------------------------------------------------------------*/
 
-static int ep0_queue(struct fsg_dev *fsg)
+static int ep0_queue(struct fsg_common *common)
 {
 	int	rc;
 
-	rc = usb_ep_queue(fsg->ep0, fsg->ep0req, GFP_ATOMIC);
-	fsg->ep0->driver_data = fsg;
+	rc = usb_ep_queue(common->ep0, common->ep0req, GFP_ATOMIC);
+	common->ep0->driver_data = common;
 	if (rc != 0 && rc != -ESHUTDOWN) {
-
 		/* We can't do much more than wait for a reset */
-		WARNING(fsg, "error in submission: %s --> %d\n",
-				fsg->ep0->name, rc);
+		WARNING(common, "error in submission: %s --> %d\n",
+			common->ep0->name, rc);
 	}
 	return rc;
 }
@@ -515,32 +524,32 @@ static int ep0_queue(struct fsg_dev *fsg)
 
 static void bulk_in_complete(struct usb_ep *ep, struct usb_request *req)
 {
-	struct fsg_dev		*fsg = ep->driver_data;
+	struct fsg_common	*common = ep->driver_data;
 	struct fsg_buffhd	*bh = req->context;
 
 	if (req->status || req->actual != req->length)
-		DBG(fsg, "%s --> %d, %u/%u\n", __func__,
+		DBG(common, "%s --> %d, %u/%u\n", __func__,
 				req->status, req->actual, req->length);
 	if (req->status == -ECONNRESET)		/* Request was cancelled */
 		usb_ep_fifo_flush(ep);
 
 	/* Hold the lock while we update the request and buffer states */
 	smp_wmb();
-	spin_lock(&fsg->lock);
+	spin_lock(&common->lock);
 	bh->inreq_busy = 0;
 	bh->state = BUF_STATE_EMPTY;
-	wakeup_thread(fsg);
-	spin_unlock(&fsg->lock);
+	wakeup_thread(common);
+	spin_unlock(&common->lock);
 }
 
 static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
 {
-	struct fsg_dev		*fsg = ep->driver_data;
+	struct fsg_common	*common = ep->driver_data;
 	struct fsg_buffhd	*bh = req->context;
 
-	dump_msg(fsg, "bulk-out", req->buf, req->actual);
+	dump_msg(common, "bulk-out", req->buf, req->actual);
 	if (req->status || req->actual != bh->bulk_out_intended_length)
-		DBG(fsg, "%s --> %d, %u/%u\n", __func__,
+		DBG(common, "%s --> %d, %u/%u\n", __func__,
 				req->status, req->actual,
 				bh->bulk_out_intended_length);
 	if (req->status == -ECONNRESET)		/* Request was cancelled */
@@ -548,11 +557,11 @@ static void bulk_out_complete(struct usb_ep *ep, struct usb_request *req)
 
 	/* Hold the lock while we update the request and buffer states */
 	smp_wmb();
-	spin_lock(&fsg->lock);
+	spin_lock(&common->lock);
 	bh->outreq_busy = 0;
 	bh->state = BUF_STATE_FULL;
-	wakeup_thread(fsg);
-	spin_unlock(&fsg->lock);
+	wakeup_thread(common);
+	spin_unlock(&common->lock);
 }
 
 
@@ -564,12 +573,12 @@ static int fsg_setup(struct usb_function *f,
 		const struct usb_ctrlrequest *ctrl)
 {
 	struct fsg_dev		*fsg = fsg_from_func(f);
-	struct usb_request	*req = fsg->ep0req;
+	struct usb_request	*req = fsg->common->ep0req;
 	u16			w_index = le16_to_cpu(ctrl->wIndex);
 	u16			w_value = le16_to_cpu(ctrl->wValue);
 	u16			w_length = le16_to_cpu(ctrl->wLength);
 
-	if (!fsg->config)
+	if (!fsg->common->config)
 		return -EOPNOTSUPP;
 
 	switch (ctrl->bRequest) {
@@ -584,7 +593,7 @@ static int fsg_setup(struct usb_function *f,
 		/* Raise an exception to stop the current operation
 		 * and reinitialize our state. */
 		DBG(fsg, "bulk reset request\n");
-		raise_exception(fsg, FSG_STATE_RESET);
+		raise_exception(fsg->common, FSG_STATE_RESET);
 		return DELAYED_STATUS;
 
 	case USB_BULK_GET_MAX_LUN_REQUEST:
@@ -622,10 +631,10 @@ static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
 	if (ep == fsg->bulk_in)
 		dump_msg(fsg, "bulk-in", req->buf, req->length);
 
-	spin_lock_irq(&fsg->lock);
+	spin_lock_irq(&fsg->common->lock);
 	*pbusy = 1;
 	*state = BUF_STATE_BUSY;
-	spin_unlock_irq(&fsg->lock);
+	spin_unlock_irq(&fsg->common->lock);
 	rc = usb_ep_queue(ep, req, GFP_KERNEL);
 	if (rc != 0) {
 		*pbusy = 0;
@@ -642,8 +651,18 @@ static void start_transfer(struct fsg_dev *fsg, struct usb_ep *ep,
 	}
 }
 
+#define START_TRANSFER_OR(common, ep_name, req, pbusy, state)		\
+	if (fsg_is_set(common))						\
+		start_transfer((common)->fsg, (common)->fsg->ep_name,	\
+			       req, pbusy, state);			\
+	else
+
+#define START_TRANSFER(common, ep_name, req, pbusy, state)		\
+	START_TRANSFER_OR(common, ep_name, req, pbusy, state) (void)0
+
+
 
-static int sleep_thread(struct fsg_dev *fsg)
+static int sleep_thread(struct fsg_common *common)
 {
 	int	rc = 0;
 
@@ -655,21 +674,21 @@ static int sleep_thread(struct fsg_dev *fsg)
 			rc = -EINTR;
 			break;
 		}
-		if (fsg->thread_wakeup_needed)
+		if (common->thread_wakeup_needed)
 			break;
 		schedule();
 	}
 	__set_current_state(TASK_RUNNING);
-	fsg->thread_wakeup_needed = 0;
+	common->thread_wakeup_needed = 0;
 	return rc;
 }
 
 
 /*-------------------------------------------------------------------------*/
 
-static int do_read(struct fsg_dev *fsg)
+static int do_read(struct fsg_common *common)
 {
-	struct fsg_lun		*curlun = fsg->common->curlun;
+	struct fsg_lun		*curlun = common->curlun;
 	u32			lba;
 	struct fsg_buffhd	*bh;
 	int			rc;
@@ -681,15 +700,15 @@ static int do_read(struct fsg_dev *fsg)
 
 	/* Get the starting Logical Block Address and check that it's
 	 * not too big */
-	if (fsg->common->cmnd[0] == SC_READ_6)
-		lba = get_unaligned_be24(&fsg->common->cmnd[1]);
+	if (common->cmnd[0] == SC_READ_6)
+		lba = get_unaligned_be24(&common->cmnd[1]);
 	else {
-		lba = get_unaligned_be32(&fsg->common->cmnd[2]);
+		lba = get_unaligned_be32(&common->cmnd[2]);
 
 		/* We allow DPO (Disable Page Out = don't save data in the
 		 * cache) and FUA (Force Unit Access = don't read from the
 		 * cache), but we don't implement them. */
-		if ((fsg->common->cmnd[1] & ~0x18) != 0) {
+		if ((common->cmnd[1] & ~0x18) != 0) {
 			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 			return -EINVAL;
 		}
@@ -701,7 +720,7 @@ static int do_read(struct fsg_dev *fsg)
 	file_offset = ((loff_t) lba) << 9;
 
 	/* Carry out the file reads */
-	amount_left = fsg->data_size_from_cmnd;
+	amount_left = common->data_size_from_cmnd;
 	if (unlikely(amount_left == 0))
 		return -EIO;		/* No default reply */
 
@@ -724,9 +743,9 @@ static int do_read(struct fsg_dev *fsg)
 					partial_page);
 
 		/* Wait for the next buffer to become available */
-		bh = fsg->common->next_buffhd_to_fill;
+		bh = common->next_buffhd_to_fill;
 		while (bh->state != BUF_STATE_EMPTY) {
-			rc = sleep_thread(fsg);
+			rc = sleep_thread(common);
 			if (rc)
 				return rc;
 		}
@@ -765,7 +784,7 @@ static int do_read(struct fsg_dev *fsg)
 		}
 		file_offset  += nread;
 		amount_left  -= nread;
-		fsg->residue -= nread;
+		common->residue -= nread;
 		bh->inreq->length = nread;
 		bh->state = BUF_STATE_FULL;
 
@@ -782,9 +801,12 @@ static int do_read(struct fsg_dev *fsg)
 
 		/* Send this buffer and go read some more */
 		bh->inreq->zero = 0;
-		start_transfer(fsg, fsg->bulk_in, bh->inreq,
-				&bh->inreq_busy, &bh->state);
-		fsg->common->next_buffhd_to_fill = bh->next;
+		START_TRANSFER_OR(common, bulk_in, bh->inreq,
+			       &bh->inreq_busy, &bh->state)
+			/* Don't know what to do if
+			 * common->fsg is NULL */
+			return -EIO;
+		common->next_buffhd_to_fill = bh->next;
 	}
 
 	return -EIO;		/* No default reply */
@@ -793,9 +815,9 @@ static int do_read(struct fsg_dev *fsg)
 
 /*-------------------------------------------------------------------------*/
 
-static int do_write(struct fsg_dev *fsg)
+static int do_write(struct fsg_common *common)
 {
-	struct fsg_lun		*curlun = fsg->common->curlun;
+	struct fsg_lun		*curlun = common->curlun;
 	u32			lba;
 	struct fsg_buffhd	*bh;
 	int			get_some_more;
@@ -816,20 +838,20 @@ static int do_write(struct fsg_dev *fsg)
 
 	/* Get the starting Logical Block Address and check that it's
 	 * not too big */
-	if (fsg->common->cmnd[0] == SC_WRITE_6)
-		lba = get_unaligned_be24(&fsg->common->cmnd[1]);
+	if (common->cmnd[0] == SC_WRITE_6)
+		lba = get_unaligned_be24(&common->cmnd[1]);
 	else {
-		lba = get_unaligned_be32(&fsg->common->cmnd[2]);
+		lba = get_unaligned_be32(&common->cmnd[2]);
 
 		/* We allow DPO (Disable Page Out = don't save data in the
 		 * cache) and FUA (Force Unit Access = write directly to the
 		 * medium).  We don't implement DPO; we implement FUA by
 		 * performing synchronous output. */
-		if ((fsg->common->cmnd[1] & ~0x18) != 0) {
+		if (common->cmnd[1] & ~0x18) {
 			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 			return -EINVAL;
 		}
-		if (fsg->common->cmnd[1] & 0x08) {	/* FUA */
+		if (common->cmnd[1] & 0x08) {	/* FUA */
 			spin_lock(&curlun->filp->f_lock);
 			curlun->filp->f_flags |= O_SYNC;
 			spin_unlock(&curlun->filp->f_lock);
@@ -843,12 +865,13 @@ static int do_write(struct fsg_dev *fsg)
 	/* Carry out the file writes */
 	get_some_more = 1;
 	file_offset = usb_offset = ((loff_t) lba) << 9;
-	amount_left_to_req = amount_left_to_write = fsg->data_size_from_cmnd;
+	amount_left_to_req = common->data_size_from_cmnd;
+	amount_left_to_write = common->data_size_from_cmnd;
 
 	while (amount_left_to_write > 0) {
 
 		/* Queue a request for more data from the host */
-		bh = fsg->common->next_buffhd_to_fill;
+		bh = common->next_buffhd_to_fill;
 		if (bh->state == BUF_STATE_EMPTY && get_some_more) {
 
 			/* Figure out how much we want to get:
@@ -887,7 +910,7 @@ static int do_write(struct fsg_dev *fsg)
 
 			/* Get the next buffer */
 			usb_offset += amount;
-			fsg->usb_amount_left -= amount;
+			common->usb_amount_left -= amount;
 			amount_left_to_req -= amount;
 			if (amount_left_to_req == 0)
 				get_some_more = 0;
@@ -897,19 +920,22 @@ static int do_write(struct fsg_dev *fsg)
 			bh->outreq->length = amount;
 			bh->bulk_out_intended_length = amount;
 			bh->outreq->short_not_ok = 1;
-			start_transfer(fsg, fsg->bulk_out, bh->outreq,
-					&bh->outreq_busy, &bh->state);
-			fsg->common->next_buffhd_to_fill = bh->next;
+			START_TRANSFER_OR(common, bulk_out, bh->outreq,
+					  &bh->outreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
 			continue;
 		}
 
 		/* Write the received data to the backing file */
-		bh = fsg->common->next_buffhd_to_drain;
+		bh = common->next_buffhd_to_drain;
 		if (bh->state == BUF_STATE_EMPTY && !get_some_more)
 			break;			/* We stopped early */
 		if (bh->state == BUF_STATE_FULL) {
 			smp_rmb();
-			fsg->common->next_buffhd_to_drain = bh->next;
+			common->next_buffhd_to_drain = bh->next;
 			bh->state = BUF_STATE_EMPTY;
 
 			/* Did something go wrong with the transfer? */
@@ -952,7 +978,7 @@ static int do_write(struct fsg_dev *fsg)
 			}
 			file_offset += nwritten;
 			amount_left_to_write -= nwritten;
-			fsg->residue -= nwritten;
+			common->residue -= nwritten;
 
 			/* If an error occurred, report it and its position */
 			if (nwritten < amount) {
@@ -964,14 +990,14 @@ static int do_write(struct fsg_dev *fsg)
 
 			/* Did the host decide to stop early? */
 			if (bh->outreq->actual != bh->outreq->length) {
-				fsg->short_packet_received = 1;
+				common->short_packet_received = 1;
 				break;
 			}
 			continue;
 		}
 
 		/* Wait for something to happen */
-		rc = sleep_thread(fsg);
+		rc = sleep_thread(common);
 		if (rc)
 			return rc;
 	}
@@ -982,9 +1008,9 @@ static int do_write(struct fsg_dev *fsg)
 
 /*-------------------------------------------------------------------------*/
 
-static int do_synchronize_cache(struct fsg_dev *fsg)
+static int do_synchronize_cache(struct fsg_common *common)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
+	struct fsg_lun	*curlun = common->curlun;
 	int		rc;
 
 	/* We ignore the requested LBA and write out all file's
@@ -1008,12 +1034,12 @@ static void invalidate_sub(struct fsg_lun *curlun)
 	VLDBG(curlun, "invalidate_inode_pages -> %ld\n", rc);
 }
 
-static int do_verify(struct fsg_dev *fsg)
+static int do_verify(struct fsg_common *common)
 {
-	struct fsg_lun		*curlun = fsg->common->curlun;
+	struct fsg_lun		*curlun = common->curlun;
 	u32			lba;
 	u32			verification_length;
-	struct fsg_buffhd	*bh = fsg->common->next_buffhd_to_fill;
+	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
 	loff_t			file_offset, file_offset_tmp;
 	u32			amount_left;
 	unsigned int		amount;
@@ -1021,7 +1047,7 @@ static int do_verify(struct fsg_dev *fsg)
 
 	/* Get the starting Logical Block Address and check that it's
 	 * not too big */
-	lba = get_unaligned_be32(&fsg->common->cmnd[2]);
+	lba = get_unaligned_be32(&common->cmnd[2]);
 	if (lba >= curlun->num_sectors) {
 		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;
 		return -EINVAL;
@@ -1029,12 +1055,12 @@ static int do_verify(struct fsg_dev *fsg)
 
 	/* We allow DPO (Disable Page Out = don't save data in the
 	 * cache) but we don't implement it. */
-	if ((fsg->common->cmnd[1] & ~0x10) != 0) {
+	if (common->cmnd[1] & ~0x10) {
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
 
-	verification_length = get_unaligned_be16(&fsg->common->cmnd[7]);
+	verification_length = get_unaligned_be16(&common->cmnd[7]);
 	if (unlikely(verification_length == 0))
 		return -EIO;		/* No default reply */
 
@@ -1106,13 +1132,13 @@ static int do_verify(struct fsg_dev *fsg)
 
 /*-------------------------------------------------------------------------*/
 
-static int do_inquiry(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_inquiry(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun *curlun = fsg->common->curlun;
+	struct fsg_lun *curlun = common->curlun;
 	u8	*buf = (u8 *) bh->buf;
 
 	if (!curlun) {		/* Unsupported LUNs are okay */
-		fsg->bad_lun_okay = 1;
+		common->bad_lun_okay = 1;
 		memset(buf, 0, 36);
 		buf[0] = 0x7f;		/* Unsupported, no device-type */
 		buf[4] = 31;		/* Additional length */
@@ -1127,15 +1153,14 @@ static int do_inquiry(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 	buf[5] = 0;		/* No special options */
 	buf[6] = 0;
 	buf[7] = 0;
-	memcpy(buf + 8, fsg->common->inquiry_string,
-	       sizeof fsg->common->inquiry_string);
+	memcpy(buf + 8, common->inquiry_string, sizeof common->inquiry_string);
 	return 36;
 }
 
 
-static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_request_sense(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
+	struct fsg_lun	*curlun = common->curlun;
 	u8		*buf = (u8 *) bh->buf;
 	u32		sd, sdinfo;
 	int		valid;
@@ -1163,7 +1188,7 @@ static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 #endif
 
 	if (!curlun) {		/* Unsupported LUNs are okay */
-		fsg->bad_lun_okay = 1;
+		common->bad_lun_okay = 1;
 		sd = SS_LOGICAL_UNIT_NOT_SUPPORTED;
 		sdinfo = 0;
 		valid = 0;
@@ -1187,11 +1212,11 @@ static int do_request_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 }
 
 
-static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_read_capacity(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
-	u32		lba = get_unaligned_be32(&fsg->common->cmnd[2]);
-	int		pmi = fsg->common->cmnd[8];
+	struct fsg_lun	*curlun = common->curlun;
+	u32		lba = get_unaligned_be32(&common->cmnd[2]);
+	int		pmi = common->cmnd[8];
 	u8		*buf = (u8 *) bh->buf;
 
 	/* Check the PMI and LBA fields */
@@ -1207,14 +1232,14 @@ static int do_read_capacity(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 }
 
 
-static int do_read_header(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_read_header(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
-	int		msf = fsg->common->cmnd[1] & 0x02;
-	u32		lba = get_unaligned_be32(&fsg->common->cmnd[2]);
+	struct fsg_lun	*curlun = common->curlun;
+	int		msf = common->cmnd[1] & 0x02;
+	u32		lba = get_unaligned_be32(&common->cmnd[2]);
 	u8		*buf = (u8 *) bh->buf;
 
-	if ((fsg->common->cmnd[1] & ~0x02) != 0) {	/* Mask away MSF */
+	if (common->cmnd[1] & ~0x02) {		/* Mask away MSF */
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
@@ -1230,14 +1255,14 @@ static int do_read_header(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 }
 
 
-static int do_read_toc(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_read_toc(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
-	int		msf = fsg->common->cmnd[1] & 0x02;
-	int		start_track = fsg->common->cmnd[6];
+	struct fsg_lun	*curlun = common->curlun;
+	int		msf = common->cmnd[1] & 0x02;
+	int		start_track = common->cmnd[6];
 	u8		*buf = (u8 *) bh->buf;
 
-	if ((fsg->common->cmnd[1] & ~0x02) != 0 ||	/* Mask away MSF */
+	if ((common->cmnd[1] & ~0x02) != 0 ||	/* Mask away MSF */
 			start_track > 1) {
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
@@ -1258,10 +1283,10 @@ static int do_read_toc(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 }
 
 
-static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_mode_sense(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
-	int		mscmnd = fsg->common->cmnd[0];
+	struct fsg_lun	*curlun = common->curlun;
+	int		mscmnd = common->cmnd[0];
 	u8		*buf = (u8 *) bh->buf;
 	u8		*buf0 = buf;
 	int		pc, page_code;
@@ -1269,12 +1294,12 @@ static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 	int		valid_page = 0;
 	int		len, limit;
 
-	if ((fsg->common->cmnd[1] & ~0x08) != 0) {	/* Mask away DBD */
+	if ((common->cmnd[1] & ~0x08) != 0) {	/* Mask away DBD */
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
-	pc = fsg->common->cmnd[2] >> 6;
-	page_code = fsg->common->cmnd[2] & 0x3f;
+	pc = common->cmnd[2] >> 6;
+	page_code = common->cmnd[2] & 0x3f;
 	if (pc == 3) {
 		curlun->sense_data = SS_SAVING_PARAMETERS_NOT_SUPPORTED;
 		return -EINVAL;
@@ -1339,32 +1364,32 @@ static int do_mode_sense(struct fsg_dev *fsg, struct fsg_buffhd *bh)
 }
 
 
-static int do_start_stop(struct fsg_dev *fsg)
+static int do_start_stop(struct fsg_common *common)
 {
-	if (!fsg->common->curlun) {
+	if (!common->curlun) {
 		return -EINVAL;
-	} else if (!fsg->common->curlun->removable) {
-		fsg->common->curlun->sense_data = SS_INVALID_COMMAND;
+	} else if (!common->curlun->removable) {
+		common->curlun->sense_data = SS_INVALID_COMMAND;
 		return -EINVAL;
 	}
 	return 0;
 }
 
 
-static int do_prevent_allow(struct fsg_dev *fsg)
+static int do_prevent_allow(struct fsg_common *common)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
+	struct fsg_lun	*curlun = common->curlun;
 	int		prevent;
 
-	if (!fsg->common->curlun) {
+	if (!common->curlun) {
 		return -EINVAL;
-	} else if (!fsg->common->curlun->removable) {
-		fsg->common->curlun->sense_data = SS_INVALID_COMMAND;
+	} else if (!common->curlun->removable) {
+		common->curlun->sense_data = SS_INVALID_COMMAND;
 		return -EINVAL;
 	}
 
-	prevent = fsg->common->cmnd[4] & 0x01;
-	if ((fsg->common->cmnd[4] & ~0x01) != 0) {	/* Mask away Prevent */
+	prevent = common->cmnd[4] & 0x01;
+	if ((common->cmnd[4] & ~0x01) != 0) {	/* Mask away Prevent */
 		curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 		return -EINVAL;
 	}
@@ -1376,10 +1401,10 @@ static int do_prevent_allow(struct fsg_dev *fsg)
 }
 
 
-static int do_read_format_capacities(struct fsg_dev *fsg,
+static int do_read_format_capacities(struct fsg_common *common,
 			struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
+	struct fsg_lun	*curlun = common->curlun;
 	u8		*buf = (u8 *) bh->buf;
 
 	buf[0] = buf[1] = buf[2] = 0;
@@ -1394,12 +1419,13 @@ static int do_read_format_capacities(struct fsg_dev *fsg,
 }
 
 
-static int do_mode_select(struct fsg_dev *fsg, struct fsg_buffhd *bh)
+static int do_mode_select(struct fsg_common *common, struct fsg_buffhd *bh)
 {
-	struct fsg_lun	*curlun = fsg->common->curlun;
+	struct fsg_lun	*curlun = common->curlun;
 
 	/* We don't support MODE SELECT */
-	curlun->sense_data = SS_INVALID_COMMAND;
+	if (curlun)
+		curlun->sense_data = SS_INVALID_COMMAND;
 	return -EINVAL;
 }
 
@@ -1459,73 +1485,78 @@ static int pad_with_zeros(struct fsg_dev *fsg)
 	int			rc;
 
 	bh->state = BUF_STATE_EMPTY;		/* For the first iteration */
-	fsg->usb_amount_left = nkeep + fsg->residue;
-	while (fsg->usb_amount_left > 0) {
+	fsg->common->usb_amount_left = nkeep + fsg->common->residue;
+	while (fsg->common->usb_amount_left > 0) {
 
 		/* Wait for the next buffer to be free */
 		while (bh->state != BUF_STATE_EMPTY) {
-			rc = sleep_thread(fsg);
+			rc = sleep_thread(fsg->common);
 			if (rc)
 				return rc;
 		}
 
-		nsend = min(fsg->usb_amount_left, FSG_BUFLEN);
+		nsend = min(fsg->common->usb_amount_left, FSG_BUFLEN);
 		memset(bh->buf + nkeep, 0, nsend - nkeep);
 		bh->inreq->length = nsend;
 		bh->inreq->zero = 0;
 		start_transfer(fsg, fsg->bulk_in, bh->inreq,
 				&bh->inreq_busy, &bh->state);
 		bh = fsg->common->next_buffhd_to_fill = bh->next;
-		fsg->usb_amount_left -= nsend;
+		fsg->common->usb_amount_left -= nsend;
 		nkeep = 0;
 	}
 	return 0;
 }
 
-static int throw_away_data(struct fsg_dev *fsg)
+static int throw_away_data(struct fsg_common *common)
 {
 	struct fsg_buffhd	*bh;
 	u32			amount;
 	int			rc;
 
-	for (bh = fsg->common->next_buffhd_to_drain;
-	     bh->state != BUF_STATE_EMPTY || fsg->usb_amount_left > 0;
-	     bh = fsg->common->next_buffhd_to_drain) {
+	for (bh = common->next_buffhd_to_drain;
+	     bh->state != BUF_STATE_EMPTY || common->usb_amount_left > 0;
+	     bh = common->next_buffhd_to_drain) {
 
 		/* Throw away the data in a filled buffer */
 		if (bh->state == BUF_STATE_FULL) {
 			smp_rmb();
 			bh->state = BUF_STATE_EMPTY;
-			fsg->common->next_buffhd_to_drain = bh->next;
+			common->next_buffhd_to_drain = bh->next;
 
 			/* A short packet or an error ends everything */
 			if (bh->outreq->actual != bh->outreq->length ||
 					bh->outreq->status != 0) {
-				raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
+				raise_exception(common,
+						FSG_STATE_ABORT_BULK_OUT);
 				return -EINTR;
 			}
 			continue;
 		}
 
 		/* Try to submit another request if we need one */
-		bh = fsg->common->next_buffhd_to_fill;
-		if (bh->state == BUF_STATE_EMPTY && fsg->usb_amount_left > 0) {
-			amount = min(fsg->usb_amount_left, FSG_BUFLEN);
+		bh = common->next_buffhd_to_fill;
+		if (bh->state == BUF_STATE_EMPTY
+		 && common->usb_amount_left > 0) {
+			amount = min(common->usb_amount_left, FSG_BUFLEN);
 
 			/* amount is always divisible by 512, hence by
 			 * the bulk-out maxpacket size */
 			bh->outreq->length = amount;
 			bh->bulk_out_intended_length = amount;
 			bh->outreq->short_not_ok = 1;
-			start_transfer(fsg, fsg->bulk_out, bh->outreq,
-					&bh->outreq_busy, &bh->state);
-			fsg->common->next_buffhd_to_fill = bh->next;
-			fsg->usb_amount_left -= amount;
+			START_TRANSFER_OR(common, bulk_out, bh->outreq,
+					  &bh->outreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
+			common->usb_amount_left -= amount;
 			continue;
 		}
 
 		/* Otherwise wait for something to happen */
-		rc = sleep_thread(fsg);
+		rc = sleep_thread(common);
 		if (rc)
 			return rc;
 	}
@@ -1533,12 +1564,12 @@ static int throw_away_data(struct fsg_dev *fsg)
 }
 
 
-static int finish_reply(struct fsg_dev *fsg)
+static int finish_reply(struct fsg_common *common)
 {
-	struct fsg_buffhd	*bh = fsg->common->next_buffhd_to_fill;
+	struct fsg_buffhd	*bh = common->next_buffhd_to_fill;
 	int			rc = 0;
 
-	switch (fsg->data_dir) {
+	switch (common->data_dir) {
 	case DATA_DIR_NONE:
 		break;			/* Nothing to send */
 
@@ -1547,47 +1578,60 @@ static int finish_reply(struct fsg_dev *fsg)
 	 * try to send or receive any data.  So stall both bulk pipes
 	 * if we can and wait for a reset. */
 	case DATA_DIR_UNKNOWN:
-		if (fsg->can_stall) {
-			fsg_set_halt(fsg, fsg->bulk_out);
-			rc = halt_bulk_in_endpoint(fsg);
+		if (!common->can_stall) {
+			/* Nothing */
+		} else if (fsg_is_set(common)) {
+			fsg_set_halt(common->fsg, common->fsg->bulk_out);
+			rc = halt_bulk_in_endpoint(common->fsg);
+		} else {
+			/* Don't know what to do if common->fsg is NULL */
+			rc = -EIO;
 		}
 		break;
 
 	/* All but the last buffer of data must have already been sent */
 	case DATA_DIR_TO_HOST:
-		if (fsg->data_size == 0) {
+		if (common->data_size == 0) {
 			/* Nothing to send */
 
 		/* If there's no residue, simply send the last buffer */
-		} else if (fsg->residue == 0) {
+		} else if (common->residue == 0) {
 			bh->inreq->zero = 0;
-			start_transfer(fsg, fsg->bulk_in, bh->inreq,
-					&bh->inreq_busy, &bh->state);
-			fsg->common->next_buffhd_to_fill = bh->next;
+			START_TRANSFER_OR(common, bulk_in, bh->inreq,
+					  &bh->inreq_busy, &bh->state)
+				return -EIO;
+			common->next_buffhd_to_fill = bh->next;
 
 		/* For Bulk-only, if we're allowed to stall then send the
 		 * short packet and halt the bulk-in endpoint.  If we can't
 		 * stall, pad out the remaining data with 0's. */
-		} else if (fsg->can_stall) {
+		} else if (common->can_stall) {
 			bh->inreq->zero = 1;
-			start_transfer(fsg, fsg->bulk_in, bh->inreq,
-				       &bh->inreq_busy, &bh->state);
-			fsg->common->next_buffhd_to_fill = bh->next;
-			rc = halt_bulk_in_endpoint(fsg);
+			START_TRANSFER_OR(common, bulk_in, bh->inreq,
+					  &bh->inreq_busy, &bh->state)
+				/* Don't know what to do if
+				 * common->fsg is NULL */
+				rc = -EIO;
+			common->next_buffhd_to_fill = bh->next;
+			if (common->fsg)
+				rc = halt_bulk_in_endpoint(common->fsg);
+		} else if (fsg_is_set(common)) {
+			rc = pad_with_zeros(common->fsg);
 		} else {
-			rc = pad_with_zeros(fsg);
+			/* Don't know what to do if common->fsg is NULL */
+			rc = -EIO;
 		}
 		break;
 
 	/* We have processed all we want from the data the host has sent.
 	 * There may still be outstanding bulk-out requests. */
 	case DATA_DIR_FROM_HOST:
-		if (fsg->residue == 0) {
+		if (common->residue == 0) {
 			/* Nothing to receive */
 
 		/* Did the host stop sending unexpectedly early? */
-		} else if (fsg->short_packet_received) {
-			raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
+		} else if (common->short_packet_received) {
+			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
 			rc = -EINTR;
 
 		/* We haven't processed all the incoming data.  Even though
@@ -1597,16 +1641,18 @@ static int finish_reply(struct fsg_dev *fsg)
 		 * STALL.  Not realizing the endpoint was halted, it wouldn't
 		 * clear the halt -- leading to problems later on. */
 #if 0
-		} else if (fsg->can_stall) {
-			fsg_set_halt(fsg, fsg->bulk_out);
-			raise_exception(fsg, FSG_STATE_ABORT_BULK_OUT);
+		} else if (common->can_stall) {
+			if (fsg_is_set(common))
+				fsg_set_halt(common->fsg,
+					     common->fsg->bulk_out);
+			raise_exception(common, FSG_STATE_ABORT_BULK_OUT);
 			rc = -EINTR;
 #endif
 
 		/* We can't stall.  Read in the excess data and throw it
 		 * all away. */
 		} else {
-			rc = throw_away_data(fsg);
+			rc = throw_away_data(common);
 		}
 		break;
 	}
@@ -1614,9 +1660,9 @@ static int finish_reply(struct fsg_dev *fsg)
 }
 
 
-static int send_status(struct fsg_dev *fsg)
+static int send_status(struct fsg_common *common)
 {
-	struct fsg_lun		*curlun = fsg->common->curlun;
+	struct fsg_lun		*curlun = common->curlun;
 	struct fsg_buffhd	*bh;
 	struct bulk_cs_wrap	*csw;
 	int			rc;
@@ -1624,9 +1670,9 @@ static int send_status(struct fsg_dev *fsg)
 	u32			sd, sdinfo = 0;
 
 	/* Wait for the next buffer to become available */
-	bh = fsg->common->next_buffhd_to_fill;
+	bh = common->next_buffhd_to_fill;
 	while (bh->state != BUF_STATE_EMPTY) {
-		rc = sleep_thread(fsg);
+		rc = sleep_thread(common);
 		if (rc)
 			ret