xref: /openbmc/linux/drivers/usb/storage/transport.c (revision bf070bb0)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Driver for USB Mass Storage compliant devices
4  *
5  * Current development and maintenance by:
6  *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
7  *
8  * Developed with the assistance of:
9  *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
10  *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
11  *   (c) 2002 Alan Stern <stern@rowland.org>
12  *
13  * Initial work by:
14  *   (c) 1999 Michael Gee (michael@linuxspecific.com)
15  *
16  * This driver is based on the 'USB Mass Storage Class' document. This
17  * describes in detail the protocol used to communicate with such
18  * devices.  Clearly, the designers had SCSI and ATAPI commands in
19  * mind when they created this document.  The commands are all very
20  * similar to commands in the SCSI-II and ATAPI specifications.
21  *
22  * It is important to note that in a number of cases this class
23  * exhibits class-specific exemptions from the USB specification.
24  * Notably the usage of NAK, STALL and ACK differs from the norm, in
25  * that they are used to communicate wait, failed and OK on commands.
26  *
27  * Also, for certain devices, the interrupt endpoint is used to convey
28  * status of a command.
29  *
30  * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
31  * information about this driver.
32  */
33 
34 #include <linux/sched.h>
35 #include <linux/gfp.h>
36 #include <linux/errno.h>
37 #include <linux/export.h>
38 
39 #include <linux/usb/quirks.h>
40 
41 #include <scsi/scsi.h>
42 #include <scsi/scsi_eh.h>
43 #include <scsi/scsi_device.h>
44 
45 #include "usb.h"
46 #include "transport.h"
47 #include "protocol.h"
48 #include "scsiglue.h"
49 #include "debug.h"
50 
51 #include <linux/blkdev.h>
52 #include "../../scsi/sd.h"
53 
54 
55 /***********************************************************************
56  * Data transfer routines
57  ***********************************************************************/
58 
59 /*
60  * This is subtle, so pay attention:
61  * ---------------------------------
62  * We're very concerned about races with a command abort.  Hanging this code
63  * is a sure fire way to hang the kernel.  (Note that this discussion applies
64  * only to transactions resulting from a scsi queued-command, since only
65  * these transactions are subject to a scsi abort.  Other transactions, such
66  * as those occurring during device-specific initialization, must be handled
67  * by a separate code path.)
68  *
69  * The abort function (usb_storage_command_abort() in scsiglue.c) first
70  * sets the machine state and the ABORTING bit in us->dflags to prevent
71  * new URBs from being submitted.  It then calls usb_stor_stop_transport()
72  * below, which atomically tests-and-clears the URB_ACTIVE bit in us->dflags
73  * to see if the current_urb needs to be stopped.  Likewise, the SG_ACTIVE
74  * bit is tested to see if the current_sg scatter-gather request needs to be
75  * stopped.  The timeout callback routine does much the same thing.
76  *
77  * When a disconnect occurs, the DISCONNECTING bit in us->dflags is set to
78  * prevent new URBs from being submitted, and usb_stor_stop_transport() is
79  * called to stop any ongoing requests.
80  *
81  * The submit function first verifies that the submitting is allowed
82  * (neither ABORTING nor DISCONNECTING bits are set) and that the submit
83  * completes without errors, and only then sets the URB_ACTIVE bit.  This
84  * prevents the stop_transport() function from trying to cancel the URB
85  * while the submit call is underway.  Next, the submit function must test
86  * the flags to see if an abort or disconnect occurred during the submission
87  * or before the URB_ACTIVE bit was set.  If so, it's essential to cancel
88  * the URB if it hasn't been cancelled already (i.e., if the URB_ACTIVE bit
89  * is still set).  Either way, the function must then wait for the URB to
90  * finish.  Note that the URB can still be in progress even after a call to
91  * usb_unlink_urb() returns.
92  *
93  * The idea is that (1) once the ABORTING or DISCONNECTING bit is set,
94  * either the stop_transport() function or the submitting function
95  * is guaranteed to call usb_unlink_urb() for an active URB,
96  * and (2) test_and_clear_bit() prevents usb_unlink_urb() from being
97  * called more than once or from being called during usb_submit_urb().
98  */
99 
100 /*
101  * This is the completion handler which will wake us up when an URB
102  * completes.
103  */
104 static void usb_stor_blocking_completion(struct urb *urb)
105 {
106 	struct completion *urb_done_ptr = urb->context;
107 
108 	complete(urb_done_ptr);
109 }
110 
111 /*
112  * This is the common part of the URB message submission code
113  *
114  * All URBs from the usb-storage driver involved in handling a queued scsi
115  * command _must_ pass through this function (or something like it) for the
116  * abort mechanisms to work properly.
117  */
118 static int usb_stor_msg_common(struct us_data *us, int timeout)
119 {
120 	struct completion urb_done;
121 	long timeleft;
122 	int status;
123 
124 	/* don't submit URBs during abort processing */
125 	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
126 		return -EIO;
127 
128 	/* set up data structures for the wakeup system */
129 	init_completion(&urb_done);
130 
131 	/* fill the common fields in the URB */
132 	us->current_urb->context = &urb_done;
133 	us->current_urb->transfer_flags = 0;
134 
135 	/*
136 	 * we assume that if transfer_buffer isn't us->iobuf then it
137 	 * hasn't been mapped for DMA.  Yes, this is clunky, but it's
138 	 * easier than always having the caller tell us whether the
139 	 * transfer buffer has already been mapped.
140 	 */
141 	if (us->current_urb->transfer_buffer == us->iobuf)
142 		us->current_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
143 	us->current_urb->transfer_dma = us->iobuf_dma;
144 
145 	/* submit the URB */
146 	status = usb_submit_urb(us->current_urb, GFP_NOIO);
147 	if (status) {
148 		/* something went wrong */
149 		return status;
150 	}
151 
152 	/*
153 	 * since the URB has been submitted successfully, it's now okay
154 	 * to cancel it
155 	 */
156 	set_bit(US_FLIDX_URB_ACTIVE, &us->dflags);
157 
158 	/* did an abort occur during the submission? */
159 	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
160 
161 		/* cancel the URB, if it hasn't been cancelled already */
162 		if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
163 			usb_stor_dbg(us, "-- cancelling URB\n");
164 			usb_unlink_urb(us->current_urb);
165 		}
166 	}
167 
168 	/* wait for the completion of the URB */
169 	timeleft = wait_for_completion_interruptible_timeout(
170 			&urb_done, timeout ? : MAX_SCHEDULE_TIMEOUT);
171 
172 	clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags);
173 
174 	if (timeleft <= 0) {
175 		usb_stor_dbg(us, "%s -- cancelling URB\n",
176 			     timeleft == 0 ? "Timeout" : "Signal");
177 		usb_kill_urb(us->current_urb);
178 	}
179 
180 	/* return the URB status */
181 	return us->current_urb->status;
182 }
183 
184 /*
185  * Transfer one control message, with timeouts, and allowing early
186  * termination.  Return codes are usual -Exxx, *not* USB_STOR_XFER_xxx.
187  */
188 int usb_stor_control_msg(struct us_data *us, unsigned int pipe,
189 		 u8 request, u8 requesttype, u16 value, u16 index,
190 		 void *data, u16 size, int timeout)
191 {
192 	int status;
193 
194 	usb_stor_dbg(us, "rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
195 		     request, requesttype, value, index, size);
196 
197 	/* fill in the devrequest structure */
198 	us->cr->bRequestType = requesttype;
199 	us->cr->bRequest = request;
200 	us->cr->wValue = cpu_to_le16(value);
201 	us->cr->wIndex = cpu_to_le16(index);
202 	us->cr->wLength = cpu_to_le16(size);
203 
204 	/* fill and submit the URB */
205 	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe,
206 			 (unsigned char*) us->cr, data, size,
207 			 usb_stor_blocking_completion, NULL);
208 	status = usb_stor_msg_common(us, timeout);
209 
210 	/* return the actual length of the data transferred if no error */
211 	if (status == 0)
212 		status = us->current_urb->actual_length;
213 	return status;
214 }
215 EXPORT_SYMBOL_GPL(usb_stor_control_msg);
216 
217 /*
218  * This is a version of usb_clear_halt() that allows early termination and
219  * doesn't read the status from the device -- this is because some devices
220  * crash their internal firmware when the status is requested after a halt.
221  *
222  * A definitive list of these 'bad' devices is too difficult to maintain or
223  * make complete enough to be useful.  This problem was first observed on the
224  * Hagiwara FlashGate DUAL unit.  However, bus traces reveal that neither
225  * MacOS nor Windows checks the status after clearing a halt.
226  *
227  * Since many vendors in this space limit their testing to interoperability
228  * with these two OSes, specification violations like this one are common.
229  */
230 int usb_stor_clear_halt(struct us_data *us, unsigned int pipe)
231 {
232 	int result;
233 	int endp = usb_pipeendpoint(pipe);
234 
235 	if (usb_pipein (pipe))
236 		endp |= USB_DIR_IN;
237 
238 	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
239 		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
240 		USB_ENDPOINT_HALT, endp,
241 		NULL, 0, 3*HZ);
242 
243 	if (result >= 0)
244 		usb_reset_endpoint(us->pusb_dev, endp);
245 
246 	usb_stor_dbg(us, "result = %d\n", result);
247 	return result;
248 }
249 EXPORT_SYMBOL_GPL(usb_stor_clear_halt);
250 
251 
252 /*
253  * Interpret the results of a URB transfer
254  *
255  * This function prints appropriate debugging messages, clears halts on
256  * non-control endpoints, and translates the status to the corresponding
257  * USB_STOR_XFER_xxx return code.
258  */
259 static int interpret_urb_result(struct us_data *us, unsigned int pipe,
260 		unsigned int length, int result, unsigned int partial)
261 {
262 	usb_stor_dbg(us, "Status code %d; transferred %u/%u\n",
263 		     result, partial, length);
264 	switch (result) {
265 
266 	/* no error code; did we send all the data? */
267 	case 0:
268 		if (partial != length) {
269 			usb_stor_dbg(us, "-- short transfer\n");
270 			return USB_STOR_XFER_SHORT;
271 		}
272 
273 		usb_stor_dbg(us, "-- transfer complete\n");
274 		return USB_STOR_XFER_GOOD;
275 
276 	/* stalled */
277 	case -EPIPE:
278 		/*
279 		 * for control endpoints, (used by CB[I]) a stall indicates
280 		 * a failed command
281 		 */
282 		if (usb_pipecontrol(pipe)) {
283 			usb_stor_dbg(us, "-- stall on control pipe\n");
284 			return USB_STOR_XFER_STALLED;
285 		}
286 
287 		/* for other sorts of endpoint, clear the stall */
288 		usb_stor_dbg(us, "clearing endpoint halt for pipe 0x%x\n",
289 			     pipe);
290 		if (usb_stor_clear_halt(us, pipe) < 0)
291 			return USB_STOR_XFER_ERROR;
292 		return USB_STOR_XFER_STALLED;
293 
294 	/* babble - the device tried to send more than we wanted to read */
295 	case -EOVERFLOW:
296 		usb_stor_dbg(us, "-- babble\n");
297 		return USB_STOR_XFER_LONG;
298 
299 	/* the transfer was cancelled by abort, disconnect, or timeout */
300 	case -ECONNRESET:
301 		usb_stor_dbg(us, "-- transfer cancelled\n");
302 		return USB_STOR_XFER_ERROR;
303 
304 	/* short scatter-gather read transfer */
305 	case -EREMOTEIO:
306 		usb_stor_dbg(us, "-- short read transfer\n");
307 		return USB_STOR_XFER_SHORT;
308 
309 	/* abort or disconnect in progress */
310 	case -EIO:
311 		usb_stor_dbg(us, "-- abort or disconnect in progress\n");
312 		return USB_STOR_XFER_ERROR;
313 
314 	/* the catch-all error case */
315 	default:
316 		usb_stor_dbg(us, "-- unknown error\n");
317 		return USB_STOR_XFER_ERROR;
318 	}
319 }
320 
321 /*
322  * Transfer one control message, without timeouts, but allowing early
323  * termination.  Return codes are USB_STOR_XFER_xxx.
324  */
325 int usb_stor_ctrl_transfer(struct us_data *us, unsigned int pipe,
326 		u8 request, u8 requesttype, u16 value, u16 index,
327 		void *data, u16 size)
328 {
329 	int result;
330 
331 	usb_stor_dbg(us, "rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
332 		     request, requesttype, value, index, size);
333 
334 	/* fill in the devrequest structure */
335 	us->cr->bRequestType = requesttype;
336 	us->cr->bRequest = request;
337 	us->cr->wValue = cpu_to_le16(value);
338 	us->cr->wIndex = cpu_to_le16(index);
339 	us->cr->wLength = cpu_to_le16(size);
340 
341 	/* fill and submit the URB */
342 	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe,
343 			 (unsigned char*) us->cr, data, size,
344 			 usb_stor_blocking_completion, NULL);
345 	result = usb_stor_msg_common(us, 0);
346 
347 	return interpret_urb_result(us, pipe, size, result,
348 			us->current_urb->actual_length);
349 }
350 EXPORT_SYMBOL_GPL(usb_stor_ctrl_transfer);
351 
352 /*
353  * Receive one interrupt buffer, without timeouts, but allowing early
354  * termination.  Return codes are USB_STOR_XFER_xxx.
355  *
356  * This routine always uses us->recv_intr_pipe as the pipe and
357  * us->ep_bInterval as the interrupt interval.
358  */
359 static int usb_stor_intr_transfer(struct us_data *us, void *buf,
360 				  unsigned int length)
361 {
362 	int result;
363 	unsigned int pipe = us->recv_intr_pipe;
364 	unsigned int maxp;
365 
366 	usb_stor_dbg(us, "xfer %u bytes\n", length);
367 
368 	/* calculate the max packet size */
369 	maxp = usb_maxpacket(us->pusb_dev, pipe, usb_pipeout(pipe));
370 	if (maxp > length)
371 		maxp = length;
372 
373 	/* fill and submit the URB */
374 	usb_fill_int_urb(us->current_urb, us->pusb_dev, pipe, buf,
375 			maxp, usb_stor_blocking_completion, NULL,
376 			us->ep_bInterval);
377 	result = usb_stor_msg_common(us, 0);
378 
379 	return interpret_urb_result(us, pipe, length, result,
380 			us->current_urb->actual_length);
381 }
382 
383 /*
384  * Transfer one buffer via bulk pipe, without timeouts, but allowing early
385  * termination.  Return codes are USB_STOR_XFER_xxx.  If the bulk pipe
386  * stalls during the transfer, the halt is automatically cleared.
387  */
388 int usb_stor_bulk_transfer_buf(struct us_data *us, unsigned int pipe,
389 	void *buf, unsigned int length, unsigned int *act_len)
390 {
391 	int result;
392 
393 	usb_stor_dbg(us, "xfer %u bytes\n", length);
394 
395 	/* fill and submit the URB */
396 	usb_fill_bulk_urb(us->current_urb, us->pusb_dev, pipe, buf, length,
397 		      usb_stor_blocking_completion, NULL);
398 	result = usb_stor_msg_common(us, 0);
399 
400 	/* store the actual length of the data transferred */
401 	if (act_len)
402 		*act_len = us->current_urb->actual_length;
403 	return interpret_urb_result(us, pipe, length, result,
404 			us->current_urb->actual_length);
405 }
406 EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_buf);
407 
408 /*
409  * Transfer a scatter-gather list via bulk transfer
410  *
411  * This function does basically the same thing as usb_stor_bulk_transfer_buf()
412  * above, but it uses the usbcore scatter-gather library.
413  */
414 static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
415 		struct scatterlist *sg, int num_sg, unsigned int length,
416 		unsigned int *act_len)
417 {
418 	int result;
419 
420 	/* don't submit s-g requests during abort processing */
421 	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
422 		return USB_STOR_XFER_ERROR;
423 
424 	/* initialize the scatter-gather request block */
425 	usb_stor_dbg(us, "xfer %u bytes, %d entries\n", length, num_sg);
426 	result = usb_sg_init(&us->current_sg, us->pusb_dev, pipe, 0,
427 			sg, num_sg, length, GFP_NOIO);
428 	if (result) {
429 		usb_stor_dbg(us, "usb_sg_init returned %d\n", result);
430 		return USB_STOR_XFER_ERROR;
431 	}
432 
433 	/*
434 	 * since the block has been initialized successfully, it's now
435 	 * okay to cancel it
436 	 */
437 	set_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
438 
439 	/* did an abort occur during the submission? */
440 	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
441 
442 		/* cancel the request, if it hasn't been cancelled already */
443 		if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
444 			usb_stor_dbg(us, "-- cancelling sg request\n");
445 			usb_sg_cancel(&us->current_sg);
446 		}
447 	}
448 
449 	/* wait for the completion of the transfer */
450 	usb_sg_wait(&us->current_sg);
451 	clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
452 
453 	result = us->current_sg.status;
454 	if (act_len)
455 		*act_len = us->current_sg.bytes;
456 	return interpret_urb_result(us, pipe, length, result,
457 			us->current_sg.bytes);
458 }
459 
460 /*
461  * Common used function. Transfer a complete command
462  * via usb_stor_bulk_transfer_sglist() above. Set cmnd resid
463  */
464 int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe,
465 		      struct scsi_cmnd* srb)
466 {
467 	unsigned int partial;
468 	int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
469 				      scsi_sg_count(srb), scsi_bufflen(srb),
470 				      &partial);
471 
472 	scsi_set_resid(srb, scsi_bufflen(srb) - partial);
473 	return result;
474 }
475 EXPORT_SYMBOL_GPL(usb_stor_bulk_srb);
476 
477 /*
478  * Transfer an entire SCSI command's worth of data payload over the bulk
479  * pipe.
480  *
481  * Note that this uses usb_stor_bulk_transfer_buf() and
482  * usb_stor_bulk_transfer_sglist() to achieve its goals --
483  * this function simply determines whether we're going to use
484  * scatter-gather or not, and acts appropriately.
485  */
486 int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
487 		void *buf, unsigned int length_left, int use_sg, int *residual)
488 {
489 	int result;
490 	unsigned int partial;
491 
492 	/* are we scatter-gathering? */
493 	if (use_sg) {
494 		/* use the usb core scatter-gather primitives */
495 		result = usb_stor_bulk_transfer_sglist(us, pipe,
496 				(struct scatterlist *) buf, use_sg,
497 				length_left, &partial);
498 		length_left -= partial;
499 	} else {
500 		/* no scatter-gather, just make the request */
501 		result = usb_stor_bulk_transfer_buf(us, pipe, buf,
502 				length_left, &partial);
503 		length_left -= partial;
504 	}
505 
506 	/* store the residual and return the error code */
507 	if (residual)
508 		*residual = length_left;
509 	return result;
510 }
511 EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_sg);
512 
513 /***********************************************************************
514  * Transport routines
515  ***********************************************************************/
516 
517 /*
518  * There are so many devices that report the capacity incorrectly,
519  * this routine was written to counteract some of the resulting
520  * problems.
521  */
522 static void last_sector_hacks(struct us_data *us, struct scsi_cmnd *srb)
523 {
524 	struct gendisk *disk;
525 	struct scsi_disk *sdkp;
526 	u32 sector;
527 
528 	/* To Report "Medium Error: Record Not Found */
529 	static unsigned char record_not_found[18] = {
530 		[0]	= 0x70,			/* current error */
531 		[2]	= MEDIUM_ERROR,		/* = 0x03 */
532 		[7]	= 0x0a,			/* additional length */
533 		[12]	= 0x14			/* Record Not Found */
534 	};
535 
536 	/*
537 	 * If last-sector problems can't occur, whether because the
538 	 * capacity was already decremented or because the device is
539 	 * known to report the correct capacity, then we don't need
540 	 * to do anything.
541 	 */
542 	if (!us->use_last_sector_hacks)
543 		return;
544 
545 	/* Was this command a READ(10) or a WRITE(10)? */
546 	if (srb->cmnd[0] != READ_10 && srb->cmnd[0] != WRITE_10)
547 		goto done;
548 
549 	/* Did this command access the last sector? */
550 	sector = (srb->cmnd[2] << 24) | (srb->cmnd[3] << 16) |
551 			(srb->cmnd[4] << 8) | (srb->cmnd[5]);
552 	disk = srb->request->rq_disk;
553 	if (!disk)
554 		goto done;
555 	sdkp = scsi_disk(disk);
556 	if (!sdkp)
557 		goto done;
558 	if (sector + 1 != sdkp->capacity)
559 		goto done;
560 
561 	if (srb->result == SAM_STAT_GOOD && scsi_get_resid(srb) == 0) {
562 
563 		/*
564 		 * The command succeeded.  We know this device doesn't
565 		 * have the last-sector bug, so stop checking it.
566 		 */
567 		us->use_last_sector_hacks = 0;
568 
569 	} else {
570 		/*
571 		 * The command failed.  Allow up to 3 retries in case this
572 		 * is some normal sort of failure.  After that, assume the
573 		 * capacity is wrong and we're trying to access the sector
574 		 * beyond the end.  Replace the result code and sense data
575 		 * with values that will cause the SCSI core to fail the
576 		 * command immediately, instead of going into an infinite
577 		 * (or even just a very long) retry loop.
578 		 */
579 		if (++us->last_sector_retries < 3)
580 			return;
581 		srb->result = SAM_STAT_CHECK_CONDITION;
582 		memcpy(srb->sense_buffer, record_not_found,
583 				sizeof(record_not_found));
584 	}
585 
586  done:
587 	/*
588 	 * Don't reset the retry counter for TEST UNIT READY commands,
589 	 * because they get issued after device resets which might be
590 	 * caused by a failed last-sector access.
591 	 */
592 	if (srb->cmnd[0] != TEST_UNIT_READY)
593 		us->last_sector_retries = 0;
594 }
595 
596 /*
597  * Invoke the transport and basic error-handling/recovery methods
598  *
599  * This is used by the protocol layers to actually send the message to
600  * the device and receive the response.
601  */
602 void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
603 {
604 	int need_auto_sense;
605 	int result;
606 
607 	/* send the command to the transport layer */
608 	scsi_set_resid(srb, 0);
609 	result = us->transport(srb, us);
610 
611 	/*
612 	 * if the command gets aborted by the higher layers, we need to
613 	 * short-circuit all other processing
614 	 */
615 	if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
616 		usb_stor_dbg(us, "-- command was aborted\n");
617 		srb->result = DID_ABORT << 16;
618 		goto Handle_Errors;
619 	}
620 
621 	/* if there is a transport error, reset and don't auto-sense */
622 	if (result == USB_STOR_TRANSPORT_ERROR) {
623 		usb_stor_dbg(us, "-- transport indicates error, resetting\n");
624 		srb->result = DID_ERROR << 16;
625 		goto Handle_Errors;
626 	}
627 
628 	/* if the transport provided its own sense data, don't auto-sense */
629 	if (result == USB_STOR_TRANSPORT_NO_SENSE) {
630 		srb->result = SAM_STAT_CHECK_CONDITION;
631 		last_sector_hacks(us, srb);
632 		return;
633 	}
634 
635 	srb->result = SAM_STAT_GOOD;
636 
637 	/*
638 	 * Determine if we need to auto-sense
639 	 *
640 	 * I normally don't use a flag like this, but it's almost impossible
641 	 * to understand what's going on here if I don't.
642 	 */
643 	need_auto_sense = 0;
644 
645 	/*
646 	 * If we're running the CB transport, which is incapable
647 	 * of determining status on its own, we will auto-sense
648 	 * unless the operation involved a data-in transfer.  Devices
649 	 * can signal most data-in errors by stalling the bulk-in pipe.
650 	 */
651 	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_DPCM_USB) &&
652 			srb->sc_data_direction != DMA_FROM_DEVICE) {
653 		usb_stor_dbg(us, "-- CB transport device requiring auto-sense\n");
654 		need_auto_sense = 1;
655 	}
656 
657 	/*
658 	 * If we have a failure, we're going to do a REQUEST_SENSE
659 	 * automatically.  Note that we differentiate between a command
660 	 * "failure" and an "error" in the transport mechanism.
661 	 */
662 	if (result == USB_STOR_TRANSPORT_FAILED) {
663 		usb_stor_dbg(us, "-- transport indicates command failure\n");
664 		need_auto_sense = 1;
665 	}
666 
667 	/*
668 	 * Determine if this device is SAT by seeing if the
669 	 * command executed successfully.  Otherwise we'll have
670 	 * to wait for at least one CHECK_CONDITION to determine
671 	 * SANE_SENSE support
672 	 */
673 	if (unlikely((srb->cmnd[0] == ATA_16 || srb->cmnd[0] == ATA_12) &&
674 	    result == USB_STOR_TRANSPORT_GOOD &&
675 	    !(us->fflags & US_FL_SANE_SENSE) &&
676 	    !(us->fflags & US_FL_BAD_SENSE) &&
677 	    !(srb->cmnd[2] & 0x20))) {
678 		usb_stor_dbg(us, "-- SAT supported, increasing auto-sense\n");
679 		us->fflags |= US_FL_SANE_SENSE;
680 	}
681 
682 	/*
683 	 * A short transfer on a command where we don't expect it
684 	 * is unusual, but it doesn't mean we need to auto-sense.
685 	 */
686 	if ((scsi_get_resid(srb) > 0) &&
687 	    !((srb->cmnd[0] == REQUEST_SENSE) ||
688 	      (srb->cmnd[0] == INQUIRY) ||
689 	      (srb->cmnd[0] == MODE_SENSE) ||
690 	      (srb->cmnd[0] == LOG_SENSE) ||
691 	      (srb->cmnd[0] == MODE_SENSE_10))) {
692 		usb_stor_dbg(us, "-- unexpectedly short transfer\n");
693 	}
694 
695 	/* Now, if we need to do the auto-sense, let's do it */
696 	if (need_auto_sense) {
697 		int temp_result;
698 		struct scsi_eh_save ses;
699 		int sense_size = US_SENSE_SIZE;
700 		struct scsi_sense_hdr sshdr;
701 		const u8 *scdd;
702 		u8 fm_ili;
703 
704 		/* device supports and needs bigger sense buffer */
705 		if (us->fflags & US_FL_SANE_SENSE)
706 			sense_size = ~0;
707 Retry_Sense:
708 		usb_stor_dbg(us, "Issuing auto-REQUEST_SENSE\n");
709 
710 		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, sense_size);
711 
712 		/* FIXME: we must do the protocol translation here */
713 		if (us->subclass == USB_SC_RBC || us->subclass == USB_SC_SCSI ||
714 				us->subclass == USB_SC_CYP_ATACB)
715 			srb->cmd_len = 6;
716 		else
717 			srb->cmd_len = 12;
718 
719 		/* issue the auto-sense command */
720 		scsi_set_resid(srb, 0);
721 		temp_result = us->transport(us->srb, us);
722 
723 		/* let's clean up right away */
724 		scsi_eh_restore_cmnd(srb, &ses);
725 
726 		if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
727 			usb_stor_dbg(us, "-- auto-sense aborted\n");
728 			srb->result = DID_ABORT << 16;
729 
730 			/* If SANE_SENSE caused this problem, disable it */
731 			if (sense_size != US_SENSE_SIZE) {
732 				us->fflags &= ~US_FL_SANE_SENSE;
733 				us->fflags |= US_FL_BAD_SENSE;
734 			}
735 			goto Handle_Errors;
736 		}
737 
738 		/*
739 		 * Some devices claim to support larger sense but fail when
740 		 * trying to request it. When a transport failure happens
741 		 * using US_FS_SANE_SENSE, we always retry with a standard
742 		 * (small) sense request. This fixes some USB GSM modems
743 		 */
744 		if (temp_result == USB_STOR_TRANSPORT_FAILED &&
745 				sense_size != US_SENSE_SIZE) {
746 			usb_stor_dbg(us, "-- auto-sense failure, retry small sense\n");
747 			sense_size = US_SENSE_SIZE;
748 			us->fflags &= ~US_FL_SANE_SENSE;
749 			us->fflags |= US_FL_BAD_SENSE;
750 			goto Retry_Sense;
751 		}
752 
753 		/* Other failures */
754 		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
755 			usb_stor_dbg(us, "-- auto-sense failure\n");
756 
757 			/*
758 			 * we skip the reset if this happens to be a
759 			 * multi-target device, since failure of an
760 			 * auto-sense is perfectly valid
761 			 */
762 			srb->result = DID_ERROR << 16;
763 			if (!(us->fflags & US_FL_SCM_MULT_TARG))
764 				goto Handle_Errors;
765 			return;
766 		}
767 
768 		/*
769 		 * If the sense data returned is larger than 18-bytes then we
770 		 * assume this device supports requesting more in the future.
771 		 * The response code must be 70h through 73h inclusive.
772 		 */
773 		if (srb->sense_buffer[7] > (US_SENSE_SIZE - 8) &&
774 		    !(us->fflags & US_FL_SANE_SENSE) &&
775 		    !(us->fflags & US_FL_BAD_SENSE) &&
776 		    (srb->sense_buffer[0] & 0x7C) == 0x70) {
777 			usb_stor_dbg(us, "-- SANE_SENSE support enabled\n");
778 			us->fflags |= US_FL_SANE_SENSE;
779 
780 			/*
781 			 * Indicate to the user that we truncated their sense
782 			 * because we didn't know it supported larger sense.
783 			 */
784 			usb_stor_dbg(us, "-- Sense data truncated to %i from %i\n",
785 				     US_SENSE_SIZE,
786 				     srb->sense_buffer[7] + 8);
787 			srb->sense_buffer[7] = (US_SENSE_SIZE - 8);
788 		}
789 
790 		scsi_normalize_sense(srb->sense_buffer, SCSI_SENSE_BUFFERSIZE,
791 				     &sshdr);
792 
793 		usb_stor_dbg(us, "-- Result from auto-sense is %d\n",
794 			     temp_result);
795 		usb_stor_dbg(us, "-- code: 0x%x, key: 0x%x, ASC: 0x%x, ASCQ: 0x%x\n",
796 			     sshdr.response_code, sshdr.sense_key,
797 			     sshdr.asc, sshdr.ascq);
798 #ifdef CONFIG_USB_STORAGE_DEBUG
799 		usb_stor_show_sense(us, sshdr.sense_key, sshdr.asc, sshdr.ascq);
800 #endif
801 
802 		/* set the result so the higher layers expect this data */
803 		srb->result = SAM_STAT_CHECK_CONDITION;
804 
805 		scdd = scsi_sense_desc_find(srb->sense_buffer,
806 					    SCSI_SENSE_BUFFERSIZE, 4);
807 		fm_ili = (scdd ? scdd[3] : srb->sense_buffer[2]) & 0xA0;
808 
809 		/*
810 		 * We often get empty sense data.  This could indicate that
811 		 * everything worked or that there was an unspecified
812 		 * problem.  We have to decide which.
813 		 */
814 		if (sshdr.sense_key == 0 && sshdr.asc == 0 && sshdr.ascq == 0 &&
815 		    fm_ili == 0) {
816 			/*
817 			 * If things are really okay, then let's show that.
818 			 * Zero out the sense buffer so the higher layers
819 			 * won't realize we did an unsolicited auto-sense.
820 			 */
821 			if (result == USB_STOR_TRANSPORT_GOOD) {
822 				srb->result = SAM_STAT_GOOD;
823 				srb->sense_buffer[0] = 0x0;
824 			}
825 
826 			/*
827 			 * ATA-passthru commands use sense data to report
828 			 * the command completion status, and often devices
829 			 * return Check Condition status when nothing is
830 			 * wrong.
831 			 */
832 			else if (srb->cmnd[0] == ATA_16 ||
833 					srb->cmnd[0] == ATA_12) {
834 				/* leave the data alone */
835 			}
836 
837 			/*
838 			 * If there was a problem, report an unspecified
839 			 * hardware error to prevent the higher layers from
840 			 * entering an infinite retry loop.
841 			 */
842 			else {
843 				srb->result = DID_ERROR << 16;
844 				if ((sshdr.response_code & 0x72) == 0x72)
845 					srb->sense_buffer[1] = HARDWARE_ERROR;
846 				else
847 					srb->sense_buffer[2] = HARDWARE_ERROR;
848 			}
849 		}
850 	}
851 
852 	/*
853 	 * Some devices don't work or return incorrect data the first
854 	 * time they get a READ(10) command, or for the first READ(10)
855 	 * after a media change.  If the INITIAL_READ10 flag is set,
856 	 * keep track of whether READ(10) commands succeed.  If the
857 	 * previous one succeeded and this one failed, set the REDO_READ10
858 	 * flag to force a retry.
859 	 */
860 	if (unlikely((us->fflags & US_FL_INITIAL_READ10) &&
861 			srb->cmnd[0] == READ_10)) {
862 		if (srb->result == SAM_STAT_GOOD) {
863 			set_bit(US_FLIDX_READ10_WORKED, &us->dflags);
864 		} else if (test_bit(US_FLIDX_READ10_WORKED, &us->dflags)) {
865 			clear_bit(US_FLIDX_READ10_WORKED, &us->dflags);
866 			set_bit(US_FLIDX_REDO_READ10, &us->dflags);
867 		}
868 
869 		/*
870 		 * Next, if the REDO_READ10 flag is set, return a result
871 		 * code that will cause the SCSI core to retry the READ(10)
872 		 * command immediately.
873 		 */
874 		if (test_bit(US_FLIDX_REDO_READ10, &us->dflags)) {
875 			clear_bit(US_FLIDX_REDO_READ10, &us->dflags);
876 			srb->result = DID_IMM_RETRY << 16;
877 			srb->sense_buffer[0] = 0;
878 		}
879 	}
880 
881 	/* Did we transfer less than the minimum amount required? */
882 	if ((srb->result == SAM_STAT_GOOD || srb->sense_buffer[2] == 0) &&
883 			scsi_bufflen(srb) - scsi_get_resid(srb) < srb->underflow)
884 		srb->result = DID_ERROR << 16;
885 
886 	last_sector_hacks(us, srb);
887 	return;
888 
889 	/*
890 	 * Error and abort processing: try to resynchronize with the device
891 	 * by issuing a port reset.  If that fails, try a class-specific
892 	 * device reset.
893 	 */
894   Handle_Errors:
895 
896 	/*
897 	 * Set the RESETTING bit, and clear the ABORTING bit so that
898 	 * the reset may proceed.
899 	 */
900 	scsi_lock(us_to_host(us));
901 	set_bit(US_FLIDX_RESETTING, &us->dflags);
902 	clear_bit(US_FLIDX_ABORTING, &us->dflags);
903 	scsi_unlock(us_to_host(us));
904 
905 	/*
906 	 * We must release the device lock because the pre_reset routine
907 	 * will want to acquire it.
908 	 */
909 	mutex_unlock(&us->dev_mutex);
910 	result = usb_stor_port_reset(us);
911 	mutex_lock(&us->dev_mutex);
912 
913 	if (result < 0) {
914 		scsi_lock(us_to_host(us));
915 		usb_stor_report_device_reset(us);
916 		scsi_unlock(us_to_host(us));
917 		us->transport_reset(us);
918 	}
919 	clear_bit(US_FLIDX_RESETTING, &us->dflags);
920 	last_sector_hacks(us, srb);
921 }
922 
923 /* Stop the current URB transfer */
924 void usb_stor_stop_transport(struct us_data *us)
925 {
926 	/*
927 	 * If the state machine is blocked waiting for an URB,
928 	 * let's wake it up.  The test_and_clear_bit() call
929 	 * guarantees that if a URB has just been submitted,
930 	 * it won't be cancelled more than once.
931 	 */
932 	if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
933 		usb_stor_dbg(us, "-- cancelling URB\n");
934 		usb_unlink_urb(us->current_urb);
935 	}
936 
937 	/* If we are waiting for a scatter-gather operation, cancel it. */
938 	if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
939 		usb_stor_dbg(us, "-- cancelling sg request\n");
940 		usb_sg_cancel(&us->current_sg);
941 	}
942 }
943 
944 /*
945  * Control/Bulk and Control/Bulk/Interrupt transport
946  */
947 
948 int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
949 {
950 	unsigned int transfer_length = scsi_bufflen(srb);
951 	unsigned int pipe = 0;
952 	int result;
953 
954 	/* COMMAND STAGE */
955 	/* let's send the command via the control pipe */
956 	/*
957 	 * Command is sometime (f.e. after scsi_eh_prep_cmnd) on the stack.
958 	 * Stack may be vmallocated.  So no DMA for us.  Make a copy.
959 	 */
960 	memcpy(us->iobuf, srb->cmnd, srb->cmd_len);
961 	result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
962 				      US_CBI_ADSC,
963 				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0,
964 				      us->ifnum, us->iobuf, srb->cmd_len);
965 
966 	/* check the return code for the command */
967 	usb_stor_dbg(us, "Call to usb_stor_ctrl_transfer() returned %d\n",
968 		     result);
969 
970 	/* if we stalled the command, it means command failed */
971 	if (result == USB_STOR_XFER_STALLED) {
972 		return USB_STOR_TRANSPORT_FAILED;
973 	}
974 
975 	/* Uh oh... serious problem here */
976 	if (result != USB_STOR_XFER_GOOD) {
977 		return USB_STOR_TRANSPORT_ERROR;
978 	}
979 
980 	/* DATA STAGE */
981 	/* transfer the data payload for this command, if one exists*/
982 	if (transfer_length) {
983 		pipe = srb->sc_data_direction == DMA_FROM_DEVICE ?
984 				us->recv_bulk_pipe : us->send_bulk_pipe;
985 		result = usb_stor_bulk_srb(us, pipe, srb);
986 		usb_stor_dbg(us, "CBI data stage result is 0x%x\n", result);
987 
988 		/* if we stalled the data transfer it means command failed */
989 		if (result == USB_STOR_XFER_STALLED)
990 			return USB_STOR_TRANSPORT_FAILED;
991 		if (result > USB_STOR_XFER_STALLED)
992 			return USB_STOR_TRANSPORT_ERROR;
993 	}
994 
995 	/* STATUS STAGE */
996 
997 	/*
998 	 * NOTE: CB does not have a status stage.  Silly, I know.  So
999 	 * we have to catch this at a higher level.
1000 	 */
1001 	if (us->protocol != USB_PR_CBI)
1002 		return USB_STOR_TRANSPORT_GOOD;
1003 
1004 	result = usb_stor_intr_transfer(us, us->iobuf, 2);
1005 	usb_stor_dbg(us, "Got interrupt data (0x%x, 0x%x)\n",
1006 		     us->iobuf[0], us->iobuf[1]);
1007 	if (result != USB_STOR_XFER_GOOD)
1008 		return USB_STOR_TRANSPORT_ERROR;
1009 
1010 	/*
1011 	 * UFI gives us ASC and ASCQ, like a request sense
1012 	 *
1013 	 * REQUEST_SENSE and INQUIRY don't affect the sense data on UFI
1014 	 * devices, so we ignore the information for those commands.  Note
1015 	 * that this means we could be ignoring a real error on these
1016 	 * commands, but that can't be helped.
1017 	 */
1018 	if (us->subclass == USB_SC_UFI) {
1019 		if (srb->cmnd[0] == REQUEST_SENSE ||
1020 		    srb->cmnd[0] == INQUIRY)
1021 			return USB_STOR_TRANSPORT_GOOD;
1022 		if (us->iobuf[0])
1023 			goto Failed;
1024 		return USB_STOR_TRANSPORT_GOOD;
1025 	}
1026 
1027 	/*
1028 	 * If not UFI, we interpret the data as a result code
1029 	 * The first byte should always be a 0x0.
1030 	 *
1031 	 * Some bogus devices don't follow that rule.  They stuff the ASC
1032 	 * into the first byte -- so if it's non-zero, call it a failure.
1033 	 */
1034 	if (us->iobuf[0]) {
1035 		usb_stor_dbg(us, "CBI IRQ data showed reserved bType 0x%x\n",
1036 			     us->iobuf[0]);
1037 		goto Failed;
1038 
1039 	}
1040 
1041 	/* The second byte & 0x0F should be 0x0 for good, otherwise error */
1042 	switch (us->iobuf[1] & 0x0F) {
1043 		case 0x00:
1044 			return USB_STOR_TRANSPORT_GOOD;
1045 		case 0x01:
1046 			goto Failed;
1047 	}
1048 	return USB_STOR_TRANSPORT_ERROR;
1049 
1050 	/*
1051 	 * the CBI spec requires that the bulk pipe must be cleared
1052 	 * following any data-in/out command failure (section 2.4.3.1.3)
1053 	 */
1054   Failed:
1055 	if (pipe)
1056 		usb_stor_clear_halt(us, pipe);
1057 	return USB_STOR_TRANSPORT_FAILED;
1058 }
1059 EXPORT_SYMBOL_GPL(usb_stor_CB_transport);
1060 
1061 /*
1062  * Bulk only transport
1063  */
1064 
1065 /* Determine what the maximum LUN supported is */
1066 int usb_stor_Bulk_max_lun(struct us_data *us)
1067 {
1068 	int result;
1069 
1070 	/* issue the command */
1071 	us->iobuf[0] = 0;
1072 	result = usb_stor_control_msg(us, us->recv_ctrl_pipe,
1073 				 US_BULK_GET_MAX_LUN,
1074 				 USB_DIR_IN | USB_TYPE_CLASS |
1075 				 USB_RECIP_INTERFACE,
1076 				 0, us->ifnum, us->iobuf, 1, 10*HZ);
1077 
1078 	usb_stor_dbg(us, "GetMaxLUN command result is %d, data is %d\n",
1079 		     result, us->iobuf[0]);
1080 
1081 	/*
1082 	 * If we have a successful request, return the result if valid. The
1083 	 * CBW LUN field is 4 bits wide, so the value reported by the device
1084 	 * should fit into that.
1085 	 */
1086 	if (result > 0) {
1087 		if (us->iobuf[0] < 16) {
1088 			return us->iobuf[0];
1089 		} else {
1090 			dev_info(&us->pusb_intf->dev,
1091 				 "Max LUN %d is not valid, using 0 instead",
1092 				 us->iobuf[0]);
1093 		}
1094 	}
1095 
1096 	/*
1097 	 * Some devices don't like GetMaxLUN.  They may STALL the control
1098 	 * pipe, they may return a zero-length result, they may do nothing at
1099 	 * all and timeout, or they may fail in even more bizarrely creative
1100 	 * ways.  In these cases the best approach is to use the default
1101 	 * value: only one LUN.
1102 	 */
1103 	return 0;
1104 }
1105 
1106 int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
1107 {
1108 	struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *) us->iobuf;
1109 	struct bulk_cs_wrap *bcs = (struct bulk_cs_wrap *) us->iobuf;
1110 	unsigned int transfer_length = scsi_bufflen(srb);
1111 	unsigned int residue;
1112 	int result;
1113 	int fake_sense = 0;
1114 	unsigned int cswlen;
1115 	unsigned int cbwlen = US_BULK_CB_WRAP_LEN;
1116 
1117 	/* Take care of BULK32 devices; set extra byte to 0 */
1118 	if (unlikely(us->fflags & US_FL_BULK32)) {
1119 		cbwlen = 32;
1120 		us->iobuf[31] = 0;
1121 	}
1122 
1123 	/* set up the command wrapper */
1124 	bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
1125 	bcb->DataTransferLength = cpu_to_le32(transfer_length);
1126 	bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ?
1127 		US_BULK_FLAG_IN : 0;
1128 	bcb->Tag = ++us->tag;
1129 	bcb->Lun = srb->device->lun;
1130 	if (us->fflags & US_FL_SCM_MULT_TARG)
1131 		bcb->Lun |= srb->device->id << 4;
1132 	bcb->Length = srb->cmd_len;
1133 
1134 	/* copy the command payload */
1135 	memset(bcb->CDB, 0, sizeof(bcb->CDB));
1136 	memcpy(bcb->CDB, srb->cmnd, bcb->Length);
1137 
1138 	/* send it to out endpoint */
1139 	usb_stor_dbg(us, "Bulk Command S 0x%x T 0x%x L %d F %d Trg %d LUN %d CL %d\n",
1140 		     le32_to_cpu(bcb->Signature), bcb->Tag,
1141 		     le32_to_cpu(bcb->DataTransferLength), bcb->Flags,
1142 		     (bcb->Lun >> 4), (bcb->Lun & 0x0F),
1143 		     bcb->Length);
1144 	result = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
1145 				bcb, cbwlen, NULL);
1146 	usb_stor_dbg(us, "Bulk command transfer result=%d\n", result);
1147 	if (result != USB_STOR_XFER_GOOD)
1148 		return USB_STOR_TRANSPORT_ERROR;
1149 
1150 	/* DATA STAGE */
1151 	/* send/receive data payload, if there is any */
1152 
1153 	/*
1154 	 * Some USB-IDE converter chips need a 100us delay between the
1155 	 * command phase and the data phase.  Some devices need a little
1156 	 * more than that, probably because of clock rate inaccuracies.
1157 	 */
1158 	if (unlikely(us->fflags & US_FL_GO_SLOW))
1159 		usleep_range(125, 150);
1160 
1161 	if (transfer_length) {
1162 		unsigned int pipe = srb->sc_data_direction == DMA_FROM_DEVICE ?
1163 				us->recv_bulk_pipe : us->send_bulk_pipe;
1164 		result = usb_stor_bulk_srb(us, pipe, srb);
1165 		usb_stor_dbg(us, "Bulk data transfer result 0x%x\n", result);
1166 		if (result == USB_STOR_XFER_ERROR)
1167 			return USB_STOR_TRANSPORT_ERROR;
1168 
1169 		/*
1170 		 * If the device tried to send back more data than the
1171 		 * amount requested, the spec requires us to transfer
1172 		 * the CSW anyway.  Since there's no point retrying the
1173 		 * the command, we'll return fake sense data indicating
1174 		 * Illegal Request, Invalid Field in CDB.
1175 		 */
1176 		if (result == USB_STOR_XFER_LONG)
1177 			fake_sense = 1;
1178 
1179 		/*
1180 		 * Sometimes a device will mistakenly skip the data phase
1181 		 * and go directly to the status phase without sending a
1182 		 * zero-length packet.  If we get a 13-byte response here,
1183 		 * check whether it really is a CSW.
1184 		 */
1185 		if (result == USB_STOR_XFER_SHORT &&
1186 				srb->sc_data_direction == DMA_FROM_DEVICE &&
1187 				transfer_length - scsi_get_resid(srb) ==
1188 					US_BULK_CS_WRAP_LEN) {
1189 			struct scatterlist *sg = NULL;
1190 			unsigned int offset = 0;
1191 
1192 			if (usb_stor_access_xfer_buf((unsigned char *) bcs,
1193 					US_BULK_CS_WRAP_LEN, srb, &sg,
1194 					&offset, FROM_XFER_BUF) ==
1195 						US_BULK_CS_WRAP_LEN &&
1196 					bcs->Signature ==
1197 						cpu_to_le32(US_BULK_CS_SIGN)) {
1198 				usb_stor_dbg(us, "Device skipped data phase\n");
1199 				scsi_set_resid(srb, transfer_length);
1200 				goto skipped_data_phase;
1201 			}
1202 		}
1203 	}
1204 
1205 	/*
1206 	 * See flow chart on pg 15 of the Bulk Only Transport spec for
1207 	 * an explanation of how this code works.
1208 	 */
1209 
1210 	/* get CSW for device status */
1211 	usb_stor_dbg(us, "Attempting to get CSW...\n");
1212 	result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1213 				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
1214 
1215 	/*
1216 	 * Some broken devices add unnecessary zero-length packets to the
1217 	 * end of their data transfers.  Such packets show up as 0-length
1218 	 * CSWs.  If we encounter such a thing, try to read the CSW again.
1219 	 */
1220 	if (result == USB_STOR_XFER_SHORT && cswlen == 0) {
1221 		usb_stor_dbg(us, "Received 0-length CSW; retrying...\n");
1222 		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1223 				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
1224 	}
1225 
1226 	/* did the attempt to read the CSW fail? */
1227 	if (result == USB_STOR_XFER_STALLED) {
1228 
1229 		/* get the status again */
1230 		usb_stor_dbg(us, "Attempting to get CSW (2nd try)...\n");
1231 		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1232 				bcs, US_BULK_CS_WRAP_LEN, NULL);
1233 	}
1234 
1235 	/* if we still have a failure at this point, we're in trouble */
1236 	usb_stor_dbg(us, "Bulk status result = %d\n", result);
1237 	if (result != USB_STOR_XFER_GOOD)
1238 		return USB_STOR_TRANSPORT_ERROR;
1239 
1240  skipped_data_phase:
1241 	/* check bulk status */
1242 	residue = le32_to_cpu(bcs->Residue);
1243 	usb_stor_dbg(us, "Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
1244 		     le32_to_cpu(bcs->Signature), bcs->Tag,
1245 		     residue, bcs->Status);
1246 	if (!(bcs->Tag == us->tag || (us->fflags & US_FL_BULK_IGNORE_TAG)) ||
1247 		bcs->Status > US_BULK_STAT_PHASE) {
1248 		usb_stor_dbg(us, "Bulk logical error\n");
1249 		return USB_STOR_TRANSPORT_ERROR;
1250 	}
1251 
1252 	/*
1253 	 * Some broken devices report odd signatures, so we do not check them
1254 	 * for validity against the spec. We store the first one we see,
1255 	 * and check subsequent transfers for validity against this signature.
1256 	 */
1257 	if (!us->bcs_signature) {
1258 		us->bcs_signature = bcs->Signature;
1259 		if (us->bcs_signature != cpu_to_le32(US_BULK_CS_SIGN))
1260 			usb_stor_dbg(us, "Learnt BCS signature 0x%08X\n",
1261 				     le32_to_cpu(us->bcs_signature));
1262 	} else if (bcs->Signature != us->bcs_signature) {
1263 		usb_stor_dbg(us, "Signature mismatch: got %08X, expecting %08X\n",
1264 			     le32_to_cpu(bcs->Signature),
1265 			     le32_to_cpu(us->bcs_signature));
1266 		return USB_STOR_TRANSPORT_ERROR;
1267 	}
1268 
1269 	/*
1270 	 * try to compute the actual residue, based on how much data
1271 	 * was really transferred and what the device tells us
1272 	 */
1273 	if (residue && !(us->fflags & US_FL_IGNORE_RESIDUE)) {
1274 
1275 		/*
1276 		 * Heuristically detect devices that generate bogus residues
1277 		 * by seeing what happens with INQUIRY and READ CAPACITY
1278 		 * commands.
1279 		 */
1280 		if (bcs->Status == US_BULK_STAT_OK &&
1281 				scsi_get_resid(srb) == 0 &&
1282 					((srb->cmnd[0] == INQUIRY &&
1283 						transfer_length == 36) ||
1284 					(srb->cmnd[0] == READ_CAPACITY &&
1285 						transfer_length == 8))) {
1286 			us->fflags |= US_FL_IGNORE_RESIDUE;
1287 
1288 		} else {
1289 			residue = min(residue, transfer_length);
1290 			scsi_set_resid(srb, max(scsi_get_resid(srb),
1291 			                                       (int) residue));
1292 		}
1293 	}
1294 
1295 	/* based on the status code, we report good or bad */
1296 	switch (bcs->Status) {
1297 		case US_BULK_STAT_OK:
1298 			/* device babbled -- return fake sense data */
1299 			if (fake_sense) {
1300 				memcpy(srb->sense_buffer,
1301 				       usb_stor_sense_invalidCDB,
1302 				       sizeof(usb_stor_sense_invalidCDB));
1303 				return USB_STOR_TRANSPORT_NO_SENSE;
1304 			}
1305 
1306 			/* command good -- note that data could be short */
1307 			return USB_STOR_TRANSPORT_GOOD;
1308 
1309 		case US_BULK_STAT_FAIL:
1310 			/* command failed */
1311 			return USB_STOR_TRANSPORT_FAILED;
1312 
1313 		case US_BULK_STAT_PHASE:
1314 			/*
1315 			 * phase error -- note that a transport reset will be
1316 			 * invoked by the invoke_transport() function
1317 			 */
1318 			return USB_STOR_TRANSPORT_ERROR;
1319 	}
1320 
1321 	/* we should never get here, but if we do, we're in trouble */
1322 	return USB_STOR_TRANSPORT_ERROR;
1323 }
1324 EXPORT_SYMBOL_GPL(usb_stor_Bulk_transport);
1325 
1326 /***********************************************************************
1327  * Reset routines
1328  ***********************************************************************/
1329 
1330 /*
1331  * This is the common part of the device reset code.
1332  *
1333  * It's handy that every transport mechanism uses the control endpoint for
1334  * resets.
1335  *
1336  * Basically, we send a reset with a 5-second timeout, so we don't get
1337  * jammed attempting to do the reset.
1338  */
1339 static int usb_stor_reset_common(struct us_data *us,
1340 		u8 request, u8 requesttype,
1341 		u16 value, u16 index, void *data, u16 size)
1342 {
1343 	int result;
1344 	int result2;
1345 
1346 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1347 		usb_stor_dbg(us, "No reset during disconnect\n");
1348 		return -EIO;
1349 	}
1350 
1351 	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
1352 			request, requesttype, value, index, data, size,
1353 			5*HZ);
1354 	if (result < 0) {
1355 		usb_stor_dbg(us, "Soft reset failed: %d\n", result);
1356 		return result;
1357 	}
1358 
1359 	/*
1360 	 * Give the device some time to recover from the reset,
1361 	 * but don't delay disconnect processing.
1362 	 */
1363 	wait_event_interruptible_timeout(us->delay_wait,
1364 			test_bit(US_FLIDX_DISCONNECTING, &us->dflags),
1365 			HZ*6);
1366 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1367 		usb_stor_dbg(us, "Reset interrupted by disconnect\n");
1368 		return -EIO;
1369 	}
1370 
1371 	usb_stor_dbg(us, "Soft reset: clearing bulk-in endpoint halt\n");
1372 	result = usb_stor_clear_halt(us, us->recv_bulk_pipe);
1373 
1374 	usb_stor_dbg(us, "Soft reset: clearing bulk-out endpoint halt\n");
1375 	result2 = usb_stor_clear_halt(us, us->send_bulk_pipe);
1376 
1377 	/* return a result code based on the result of the clear-halts */
1378 	if (result >= 0)
1379 		result = result2;
1380 	if (result < 0)
1381 		usb_stor_dbg(us, "Soft reset failed\n");
1382 	else
1383 		usb_stor_dbg(us, "Soft reset done\n");
1384 	return result;
1385 }
1386 
1387 /* This issues a CB[I] Reset to the device in question */
1388 #define CB_RESET_CMD_SIZE	12
1389 
1390 int usb_stor_CB_reset(struct us_data *us)
1391 {
1392 	memset(us->iobuf, 0xFF, CB_RESET_CMD_SIZE);
1393 	us->iobuf[0] = SEND_DIAGNOSTIC;
1394 	us->iobuf[1] = 4;
1395 	return usb_stor_reset_common(us, US_CBI_ADSC,
1396 				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
1397 				 0, us->ifnum, us->iobuf, CB_RESET_CMD_SIZE);
1398 }
1399 EXPORT_SYMBOL_GPL(usb_stor_CB_reset);
1400 
1401 /*
1402  * This issues a Bulk-only Reset to the device in question, including
1403  * clearing the subsequent endpoint halts that may occur.
1404  */
1405 int usb_stor_Bulk_reset(struct us_data *us)
1406 {
1407 	return usb_stor_reset_common(us, US_BULK_RESET_REQUEST,
1408 				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
1409 				 0, us->ifnum, NULL, 0);
1410 }
1411 EXPORT_SYMBOL_GPL(usb_stor_Bulk_reset);
1412 
1413 /*
1414  * Issue a USB port reset to the device.  The caller must not hold
1415  * us->dev_mutex.
1416  */
1417 int usb_stor_port_reset(struct us_data *us)
1418 {
1419 	int result;
1420 
1421 	/*for these devices we must use the class specific method */
1422 	if (us->pusb_dev->quirks & USB_QUIRK_RESET)
1423 		return -EPERM;
1424 
1425 	result = usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
1426 	if (result < 0)
1427 		usb_stor_dbg(us, "unable to lock device for reset: %d\n",
1428 			     result);
1429 	else {
1430 		/* Were we disconnected while waiting for the lock? */
1431 		if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1432 			result = -EIO;
1433 			usb_stor_dbg(us, "No reset during disconnect\n");
1434 		} else {
1435 			result = usb_reset_device(us->pusb_dev);
1436 			usb_stor_dbg(us, "usb_reset_device returns %d\n",
1437 				     result);
1438 		}
1439 		usb_unlock_device(us->pusb_dev);
1440 	}
1441 	return result;
1442 }
1443