scsi_error.c

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	memcpy((void *) SCpnt->cmnd, (void *) tur_command,
	       sizeof(tur_command));

	SCpnt->cmnd[1] = SCpnt->lun << 5;

	scsi_result = (!SCpnt->host->hostt->unchecked_isa_dma)
	    ? &scsi_result0[0] : kmalloc(512, GFP_ATOMIC | GFP_DMA);

	if (scsi_result == NULL) {
		printk("cannot allocate scsi_result in scsi_test_unit_ready.\n");
		return FAILED;
	}
	/*
	 * Zero the sense buffer.  Some host adapters automatically always request
	 * sense, so it is not a good idea that SCpnt->request_buffer and
	 * SCpnt->sense_buffer point to the same address (DB).
	 * 0 is not a valid sense code. 
	 */
	memset((void *) SCpnt->sense_buffer, 0, sizeof(SCpnt->sense_buffer));
	memset((void *) scsi_result, 0, 256);

	SCpnt->request_buffer = scsi_result;
	SCpnt->request_bufflen = 256;
	SCpnt->use_sg = 0;
	SCpnt->cmd_len = COMMAND_SIZE(SCpnt->cmnd[0]);
	SCpnt->underflow = 0;
	SCpnt->sc_data_direction = SCSI_DATA_NONE;

	scsi_send_eh_cmnd(SCpnt, SENSE_TIMEOUT);

	/* Last chance to have valid sense data */
	if (!scsi_sense_valid(SCpnt))
		memcpy((void *) SCpnt->sense_buffer,
		       SCpnt->request_buffer,
		       sizeof(SCpnt->sense_buffer));

	if (scsi_result != &scsi_result0[0] && scsi_result != NULL)
		kfree(scsi_result);

	/*
	 * When we eventually call scsi_finish, we really wish to complete
	 * the original request, so let's restore the original data. (DB)
	 */
	memcpy((void *) SCpnt->cmnd, (void *) SCpnt->data_cmnd,
	       sizeof(SCpnt->data_cmnd));
	SCpnt->request_buffer = SCpnt->buffer;
	SCpnt->request_bufflen = SCpnt->bufflen;
	SCpnt->use_sg = SCpnt->old_use_sg;
	SCpnt->cmd_len = SCpnt->old_cmd_len;
	SCpnt->sc_data_direction = SCpnt->sc_old_data_direction;
	SCpnt->underflow = SCpnt->old_underflow;

	/*
	 * Hey, we are done.  Let's look to see what happened.
	 */
	return SCpnt->eh_state;
}

/*
 * This would normally need to get the IO request lock,
 * but as it doesn't actually touch anything that needs
 * to be locked we can avoid the lock here..
 */
STATIC
void scsi_sleep_done(struct semaphore *sem)
{
	if (sem != NULL) {
		up(sem);
	}
}

void scsi_sleep(int timeout)
{
	DECLARE_MUTEX_LOCKED(sem);
	struct timer_list timer;

	init_timer(&timer);
	timer.data = (unsigned long) &sem;
	timer.expires = jiffies + timeout;
	timer.function = (void (*)(unsigned long)) scsi_sleep_done;

	SCSI_LOG_ERROR_RECOVERY(5, printk("Sleeping for timer tics %d\n", timeout));

	add_timer(&timer);

	down(&sem);
	del_timer(&timer);
}

/*
 * Function:  scsi_send_eh_cmnd
 *
 * Purpose:     Send a command out to a device as part of error recovery.
 *
 * Notes:       The initialization of the structures is quite a bit different
 *              in this case, and furthermore, there is a different completion
 *              handler.
 */
STATIC void scsi_send_eh_cmnd(Scsi_Cmnd * SCpnt, int timeout)
{
	unsigned long flags;
	struct Scsi_Host *host;

	ASSERT_LOCK(&io_request_lock, 0);

	host = SCpnt->host;

      retry:
	/*
	 * We will use a queued command if possible, otherwise we will emulate the
	 * queuing and calling of completion function ourselves.
	 */
	SCpnt->owner = SCSI_OWNER_LOWLEVEL;

	if (host->can_queue) {
		DECLARE_MUTEX_LOCKED(sem);

		SCpnt->eh_state = SCSI_STATE_QUEUED;

		scsi_add_timer(SCpnt, timeout, scsi_eh_times_out);

		/*
		 * Set up the semaphore so we wait for the command to complete.
		 */
		SCpnt->host->eh_action = &sem;
		SCpnt->request.rq_status = RQ_SCSI_BUSY;

		spin_lock_irqsave(&io_request_lock, flags);
		host->hostt->queuecommand(SCpnt, scsi_eh_done);
		spin_unlock_irqrestore(&io_request_lock, flags);

		down(&sem);

		SCpnt->host->eh_action = NULL;

		/*
		 * See if timeout.  If so, tell the host to forget about it.
		 * In other words, we don't want a callback any more.
		 */
		if (SCpnt->eh_state == SCSI_STATE_TIMEOUT) {
                        SCpnt->owner = SCSI_OWNER_LOWLEVEL;

			/*
			 * As far as the low level driver is
			 * concerned, this command is still active, so
			 * we must give the low level driver a chance
			 * to abort it. (DB) 
			 *
			 * FIXME(eric) - we are not tracking whether we could
			 * abort a timed out command or not.  Not sure how
			 * we should treat them differently anyways.
			 */
			spin_lock_irqsave(&io_request_lock, flags);
			if (SCpnt->host->hostt->eh_abort_handler)
				SCpnt->host->hostt->eh_abort_handler(SCpnt);
			spin_unlock_irqrestore(&io_request_lock, flags);
			
			SCpnt->request.rq_status = RQ_SCSI_DONE;
			SCpnt->owner = SCSI_OWNER_ERROR_HANDLER;
			
			SCpnt->eh_state = FAILED;
		}
		SCSI_LOG_ERROR_RECOVERY(5, printk("send_eh_cmnd: %p eh_state:%x\n",
						SCpnt, SCpnt->eh_state));
	} else {
		int temp;

		/*
		 * We damn well had better never use this code.  There is no timeout
		 * protection here, since we would end up waiting in the actual low
		 * level driver, we don't know how to wake it up.
		 */
		spin_lock_irqsave(&io_request_lock, flags);
		temp = host->hostt->command(SCpnt);
		spin_unlock_irqrestore(&io_request_lock, flags);

		SCpnt->result = temp;
		if (scsi_eh_completed_normally(SCpnt)) {
			SCpnt->eh_state = SUCCESS;
		} else {
			SCpnt->eh_state = FAILED;
		}
	}

	/*
	 * Now examine the actual status codes to see whether the command actually
	 * did complete normally.
	 */
	if (SCpnt->eh_state == SUCCESS) {
		switch (scsi_eh_completed_normally(SCpnt)) {
		case SUCCESS:
			SCpnt->eh_state = SUCCESS;
			break;
		case NEEDS_RETRY:
			goto retry;
		case FAILED:
		default:
			SCpnt->eh_state = FAILED;
			break;
		}
	} else {
		SCpnt->eh_state = FAILED;
	}
}

/*
 * Function:  scsi_unit_is_ready()
 *
 * Purpose:     Called after TEST_UNIT_READY is run, to test to see if
 *              the unit responded in a way that indicates it is ready.
 */
STATIC int scsi_unit_is_ready(Scsi_Cmnd * SCpnt)
{
	if (SCpnt->result) {
		if (((driver_byte(SCpnt->result) & DRIVER_SENSE) ||
		     (status_byte(SCpnt->result) & CHECK_CONDITION)) &&
		    ((SCpnt->sense_buffer[0] & 0x70) >> 4) == 7) {
			if (((SCpnt->sense_buffer[2] & 0xf) != NOT_READY) &&
			    ((SCpnt->sense_buffer[2] & 0xf) != UNIT_ATTENTION) &&
			    ((SCpnt->sense_buffer[2] & 0xf) != ILLEGAL_REQUEST)) {
				return 0;
			}
		}
	}
	return 1;
}

/*
 * Function:    scsi_eh_finish_command
 *
 * Purpose:     Handle a command that we are finished with WRT error handling.
 *
 * Arguments:   SClist - pointer to list into which we are putting completed commands.
 *              SCpnt  - command that is completing
 *
 * Notes:       We don't want to use the normal command completion while we are
 *              are still handling errors - it may cause other commands to be queued,
 *              and that would disturb what we are doing.  Thus we really want to keep
 *              a list of pending commands for final completion, and once we
 *              are ready to leave error handling we handle completion for real.
 */
STATIC void scsi_eh_finish_command(Scsi_Cmnd ** SClist, Scsi_Cmnd * SCpnt)
{
	SCpnt->state = SCSI_STATE_BHQUEUE;
	SCpnt->bh_next = *SClist;
	/*
	 * Set this back so that the upper level can correctly free up
	 * things.
	 */
	SCpnt->use_sg = SCpnt->old_use_sg;
	SCpnt->sc_data_direction = SCpnt->sc_old_data_direction;
	SCpnt->underflow = SCpnt->old_underflow;
	*SClist = SCpnt;
}

/*
 * Function:  scsi_try_to_abort_command
 *
 * Purpose:     Ask host adapter to abort a running command.
 *
 * Returns:     FAILED          Operation failed or not supported.
 *              SUCCESS         Succeeded.
 *
 * Notes:       This function will not return until the user's completion
 *              function has been called.  There is no timeout on this
 *              operation.  If the author of the low-level driver wishes
 *              this operation to be timed, they can provide this facility
 *              themselves.  Helper functions in scsi_error.c can be supplied
 *              to make this easier to do.
 *
 * Notes:       It may be possible to combine this with all of the reset
 *              handling to eliminate a lot of code duplication.  I don't
 *              know what makes more sense at the moment - this is just a
 *              prototype.
 */
STATIC int scsi_try_to_abort_command(Scsi_Cmnd * SCpnt, int timeout)
{
	int rtn;
	unsigned long flags;

	SCpnt->eh_state = FAILED;	/* Until we come up with something better */

	if (SCpnt->host->hostt->eh_abort_handler == NULL) {
		return FAILED;
	}
	/* 
	 * scsi_done was called just after the command timed out and before
	 * we had a chance to process it. (DB)
	 */
	if (SCpnt->serial_number == 0)
		return SUCCESS;

	SCpnt->owner = SCSI_OWNER_LOWLEVEL;

	spin_lock_irqsave(&io_request_lock, flags);
	rtn = SCpnt->host->hostt->eh_abort_handler(SCpnt);
	spin_unlock_irqrestore(&io_request_lock, flags);
	return rtn;
}

/*
 * Function:  scsi_try_bus_device_reset
 *
 * Purpose:     Ask host adapter to perform a bus device reset for a given
 *              device.
 *
 * Returns:     FAILED          Operation failed or not supported.
 *              SUCCESS         Succeeded.
 *
 * Notes:       There is no timeout for this operation.  If this operation is
 *              unreliable for a given host, then the host itself needs to put a
 *              timer on it, and set the host back to a consistent state prior
 *              to returning.
 */
STATIC int scsi_try_bus_device_reset(Scsi_Cmnd * SCpnt, int timeout)
{
	unsigned long flags;
	int rtn;

	SCpnt->eh_state = FAILED;	/* Until we come up with something better */

	if (SCpnt->host->hostt->eh_device_reset_handler == NULL) {
		return FAILED;
	}
	SCpnt->owner = SCSI_OWNER_LOWLEVEL;

	spin_lock_irqsave(&io_request_lock, flags);
	rtn = SCpnt->host->hostt->eh_device_reset_handler(SCpnt);
	spin_unlock_irqrestore(&io_request_lock, flags);

	if (rtn == SUCCESS)
		SCpnt->eh_state = SUCCESS;

	return SCpnt->eh_state;
}

/*
 * Function:  scsi_try_bus_reset
 *
 * Purpose:     Ask host adapter to perform a bus reset for a host.
 *
 * Returns:     FAILED          Operation failed or not supported.
 *              SUCCESS         Succeeded.
 *
 * Notes:       
 */
STATIC int scsi_try_bus_reset(Scsi_Cmnd * SCpnt)
{
	unsigned long flags;
	int rtn;

	SCpnt->eh_state = FAILED;	/* Until we come up with something better */
	SCpnt->owner = SCSI_OWNER_LOWLEVEL;
	SCpnt->serial_number_at_timeout = SCpnt->serial_number;

	if (SCpnt->host->hostt->eh_bus_reset_handler == NULL) {
		return FAILED;
	}

	spin_lock_irqsave(&io_request_lock, flags);
	rtn = SCpnt->host->hostt->eh_bus_reset_handler(SCpnt);
	spin_unlock_irqrestore(&io_request_lock, flags);

	if (rtn == SUCCESS)
		SCpnt->eh_state = SUCCESS;

	/*
	 * If we had a successful bus reset, mark the command blocks to expect
	 * a condition code of unit attention.
	 */
	scsi_sleep(BUS_RESET_SETTLE_TIME);
	if (SCpnt->eh_state == SUCCESS) {
		Scsi_Device *SDloop;
		for (SDloop = SCpnt->host->host_queue; SDloop; SDloop = SDloop->next) {
			if (SCpnt->channel == SDloop->channel) {
				SDloop->was_reset = 1;
				SDloop->expecting_cc_ua = 1;
			}
		}
	}
	return SCpnt->eh_state;
}

/*
 * Function:  scsi_try_host_reset
 *
 * Purpose:     Ask host adapter to reset itself, and the bus.
 *
 * Returns:     FAILED          Operation failed or not supported.
 *              SUCCESS         Succeeded.
 *
 * Notes:
 */
STATIC int scsi_try_host_reset(Scsi_Cmnd * SCpnt)
{
	unsigned long flags;
	int rtn;

	SCpnt->eh_state = FAILED;	/* Until we come up with something better */
	SCpnt->owner = SCSI_OWNER_LOWLEVEL;
	SCpnt->serial_number_at_timeout = SCpnt->serial_number;

	if (SCpnt->host->hostt->eh_host_reset_handler == NULL) {
		return FAILED;
	}
	spin_lock_irqsave(&io_request_lock, flags);
	rtn = SCpnt->host->hostt->eh_host_reset_handler(SCpnt);
	spin_unlock_irqrestore(&io_request_lock, flags);

	if (rtn == SUCCESS)
		SCpnt->eh_state = SUCCESS;

	/*
	 * If we had a successful host reset, mark the command blocks to expect
	 * a condition code of unit attention.
	 */
	scsi_sleep(HOST_RESET_SETTLE_TIME);
	if (SCpnt->eh_state == SUCCESS) {
		Scsi_Device *SDloop;
		for (SDloop = SCpnt->host->host_queue; SDloop; SDloop = SDloop->next) {
			SDloop->was_reset = 1;
			SDloop->expecting_cc_ua = 1;
		}
	}
	return SCpnt->eh_state;
}

/*
 * Function:  scsi_decide_disposition
 *
 * Purpose:     Examine a command block that has come back from the low-level
 *              and figure out what to do next.
 *
 * Returns:     SUCCESS         - pass on to upper level.
 *              FAILED          - pass on to error handler thread.
 *              RETRY           - command should be retried.
 *              SOFTERR         - command succeeded, but we need to log
 *                                a soft error.
 *
 * Notes:       This is *ONLY* called when we are examining the status
 *              after sending out the actual data command.  Any commands
 *              that are queued for error recovery (i.e. TEST_UNIT_READY)
 *              do *NOT* come through here.
 *
 *              NOTE - When this routine returns FAILED, it means the error
 *              handler thread is woken.  In cases where the error code
 *              indicates an error that doesn't require the error handler
 *              thread (i.e. we don't need to abort/reset), then this function
 *              should return SUCCESS.
 */
int scsi_decide_disposition(Scsi_Cmnd * SCpnt)
{
	int rtn;

	/*
	 * If the device is offline, then we clearly just pass the result back
	 * up to the top level.
	 */
	if (SCpnt->device->online == FALSE) {
		SCSI_LOG_ERROR_RECOVERY(5, printk("scsi_error.c: device offline - report as SUCCESS\n"));
		return SUCCESS;
	}
	/*
	 * First check the host byte, to see if there is anything in there
	 * that would indicate what we need to do.
	 */

	switch (host_byte(SCpnt->result)) {
	case DID_PASSTHROUGH:
		/*
		 * No matter what, pass this through to the upper layer.
		 * Nuke this special code so that it looks like we are saying
		 * DID_OK.
		 */
		SCpnt->result &= 0xff00ffff;
		return SUCCESS;
	case DID_OK:
		/*
		 * Looks good.  Drop through, and check the next byte.
		 */
		break;
	case DID_NO_CONNECT:
	case DID_BAD_TARGET:
	case DID_ABORT:
		/*
		 * Note - this means that we just report the status back to the
		 * top level driver, not that we actually think that it indicates
		 * success.
		 */
		return SUCCESS;
		/*
		 * When the low level driver returns DID_SOFT_ERROR,
		 * it is responsible for keeping an internal retry counter 
		 * in order to avoid endless loops (DB)
		 *
		 * Actually this is a bug in this function here.  We should