scsi.c

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                                set_current_state(TASK_INTERRUPTIBLE);
                        } else {
                                set_current_state(TASK_UNINTERRUPTIBLE);
                        }

                        spin_unlock_irqrestore(&device_request_lock, flags);

			/*
			 * This should block until a device command block
			 * becomes available.
			 */
                        schedule();

			spin_lock_irqsave(&device_request_lock, flags);

                        remove_wait_queue(&device->scpnt_wait, &wait);
                        /*
                         * FIXME - Isn't this redundant??  Someone
                         * else will have forced the state back to running.
                         */
                        set_current_state(TASK_RUNNING);
                        /*
                         * In the event that a signal has arrived that we need
                         * to consider, then simply return NULL.  Everyone
                         * that calls us should be prepared for this
                         * possibility, and pass the appropriate code back
                         * to the user.
                         */
                        if( interruptable ) {
                                if (signal_pending(current)) {
                                        spin_unlock_irqrestore(&device_request_lock, flags);
                                        return NULL;
                                }
                        }
		} else {
                        spin_unlock_irqrestore(&device_request_lock, flags);
			return NULL;
		}
	}

	SCpnt->request.rq_status = RQ_SCSI_BUSY;
	SCpnt->request.waiting = NULL;	/* And no one is waiting for this
					 * to complete */
	atomic_inc(&SCpnt->host->host_active);
	atomic_inc(&SCpnt->device->device_active);

	SCpnt->buffer  = NULL;
	SCpnt->bufflen = 0;
	SCpnt->request_buffer = NULL;
	SCpnt->request_bufflen = 0;

	SCpnt->use_sg = 0;	/* Reset the scatter-gather flag */
	SCpnt->old_use_sg = 0;
	SCpnt->transfersize = 0;	/* No default transfer size */
	SCpnt->cmd_len = 0;

	SCpnt->sc_data_direction = SCSI_DATA_UNKNOWN;
	SCpnt->sc_request = NULL;
	SCpnt->sc_magic = SCSI_CMND_MAGIC;

        SCpnt->result = 0;
	SCpnt->underflow = 0;	/* Do not flag underflow conditions */
	SCpnt->old_underflow = 0;
	SCpnt->resid = 0;
	SCpnt->state = SCSI_STATE_INITIALIZING;
	SCpnt->owner = SCSI_OWNER_HIGHLEVEL;

	spin_unlock_irqrestore(&device_request_lock, flags);

	SCSI_LOG_MLQUEUE(5, printk("Activating command for device %d (%d)\n",
				   SCpnt->target,
				atomic_read(&SCpnt->host->host_active)));

	return SCpnt;
}

inline void __scsi_release_command(Scsi_Cmnd * SCpnt)
{
	unsigned long flags;
        Scsi_Device * SDpnt;

	spin_lock_irqsave(&device_request_lock, flags);

        SDpnt = SCpnt->device;

	SCpnt->request.rq_status = RQ_INACTIVE;
	SCpnt->state = SCSI_STATE_UNUSED;
	SCpnt->owner = SCSI_OWNER_NOBODY;
	atomic_dec(&SCpnt->host->host_active);
	atomic_dec(&SDpnt->device_active);

	SCSI_LOG_MLQUEUE(5, printk("Deactivating command for device %d (active=%d, failed=%d)\n",
				   SCpnt->target,
				   atomic_read(&SCpnt->host->host_active),
				   SCpnt->host->host_failed));
	if (SCpnt->host->host_failed != 0) {
		SCSI_LOG_ERROR_RECOVERY(5, printk("Error handler thread %d %d\n",
						SCpnt->host->in_recovery,
						SCpnt->host->eh_active));
	}
	/*
	 * If the host is having troubles, then look to see if this was the last
	 * command that might have failed.  If so, wake up the error handler.
	 */
	if (SCpnt->host->in_recovery
	    && !SCpnt->host->eh_active
	    && SCpnt->host->host_busy == SCpnt->host->host_failed) {
		SCSI_LOG_ERROR_RECOVERY(5, printk("Waking error handler thread (%d)\n",
			     atomic_read(&SCpnt->host->eh_wait->count)));
		up(SCpnt->host->eh_wait);
	}

	spin_unlock_irqrestore(&device_request_lock, flags);

        /*
         * Wake up anyone waiting for this device.  Do this after we
         * have released the lock, as they will need it as soon as
         * they wake up.  
         */
	wake_up(&SDpnt->scpnt_wait);
}

/*
 * Function:    scsi_release_command
 *
 * Purpose:     Release a command block.
 *
 * Arguments:   SCpnt - command block we are releasing.
 *
 * Notes:       The command block can no longer be used by the caller once
 *              this funciton is called.  This is in effect the inverse
 *              of scsi_allocate_device.  Note that we also must perform
 *              a couple of additional tasks.  We must first wake up any
 *              processes that might have blocked waiting for a command
 *              block, and secondly we must hit the queue handler function
 *              to make sure that the device is busy.  Note - there is an
 *              option to not do this - there were instances where we could
 *              recurse too deeply and blow the stack if this happened
 *              when we were indirectly called from the request function
 *              itself.
 *
 *              The idea is that a lot of the mid-level internals gunk
 *              gets hidden in this function.  Upper level drivers don't
 *              have any chickens to wave in the air to get things to
 *              work reliably.
 *
 *              This function is deprecated, and drivers should be
 *              rewritten to use Scsi_Request instead of Scsi_Cmnd.
 */
void scsi_release_command(Scsi_Cmnd * SCpnt)
{
        request_queue_t *q;
        Scsi_Device * SDpnt;

        SDpnt = SCpnt->device;

        __scsi_release_command(SCpnt);

        /*
         * Finally, hit the queue request function to make sure that
         * the device is actually busy if there are requests present.
         * This won't block - if the device cannot take any more, life
         * will go on.  
         */
        q = &SDpnt->request_queue;
        scsi_queue_next_request(q, NULL);                
}

/*
 * Function:    scsi_dispatch_command
 *
 * Purpose:     Dispatch a command to the low-level driver.
 *
 * Arguments:   SCpnt - command block we are dispatching.
 *
 * Notes:
 */
int scsi_dispatch_cmd(Scsi_Cmnd * SCpnt)
{
#ifdef DEBUG_DELAY
	unsigned long clock;
#endif
	struct Scsi_Host *host;
	int rtn = 0;
	unsigned long flags = 0;
	unsigned long timeout;

	ASSERT_LOCK(&io_request_lock, 0);

#if DEBUG
	unsigned long *ret = 0;
#ifdef __mips__
	__asm__ __volatile__("move\t%0,$31":"=r"(ret));
#else
	ret = __builtin_return_address(0);
#endif
#endif

	host = SCpnt->host;

	/* Assign a unique nonzero serial_number. */
	if (++serial_number == 0)
		serial_number = 1;
	SCpnt->serial_number = serial_number;
	SCpnt->pid = scsi_pid++;

	/*
	 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
	 * we can avoid the drive not being ready.
	 */
	timeout = host->last_reset + MIN_RESET_DELAY;

	if (host->resetting && time_before(jiffies, timeout)) {
		int ticks_remaining = timeout - jiffies;
		/*
		 * NOTE: This may be executed from within an interrupt
		 * handler!  This is bad, but for now, it'll do.  The irq
		 * level of the interrupt handler has been masked out by the
		 * platform dependent interrupt handling code already, so the
		 * sti() here will not cause another call to the SCSI host's
		 * interrupt handler (assuming there is one irq-level per
		 * host).
		 */
		while (--ticks_remaining >= 0)
			mdelay(1 + 999 / HZ);
		host->resetting = 0;
	}
	if (host->hostt->use_new_eh_code) {
		scsi_add_timer(SCpnt, SCpnt->timeout_per_command, scsi_times_out);
	} else {
		scsi_add_timer(SCpnt, SCpnt->timeout_per_command,
			       scsi_old_times_out);
	}

	/*
	 * We will use a queued command if possible, otherwise we will emulate the
	 * queuing and calling of completion function ourselves.
	 */
	SCSI_LOG_MLQUEUE(3, printk("scsi_dispatch_cmnd (host = %d, channel = %d, target = %d, "
	       "command = %p, buffer = %p, \nbufflen = %d, done = %p)\n",
	SCpnt->host->host_no, SCpnt->channel, SCpnt->target, SCpnt->cmnd,
			    SCpnt->buffer, SCpnt->bufflen, SCpnt->done));

	SCpnt->state = SCSI_STATE_QUEUED;
	SCpnt->owner = SCSI_OWNER_LOWLEVEL;
	if (host->can_queue) {
		SCSI_LOG_MLQUEUE(3, printk("queuecommand : routine at %p\n",
					   host->hostt->queuecommand));
		/*
		 * Use the old error handling code if we haven't converted the driver
		 * to use the new one yet.  Note - only the new queuecommand variant
		 * passes a meaningful return value.
		 */
		if (host->hostt->use_new_eh_code) {
			/*
			 * Before we queue this command, check if the command
			 * length exceeds what the host adapter can handle.
			 */
			if (CDB_SIZE(SCpnt) <= SCpnt->host->max_cmd_len) {
				spin_lock_irqsave(&io_request_lock, flags);
				rtn = host->hostt->queuecommand(SCpnt, scsi_done);
				spin_unlock_irqrestore(&io_request_lock, flags);
				if (rtn != 0) {
					scsi_delete_timer(SCpnt);
					scsi_mlqueue_insert(SCpnt, SCSI_MLQUEUE_HOST_BUSY);
					SCSI_LOG_MLQUEUE(3, printk("queuecommand : request rejected\n"));                                
				}
			} else {
				SCSI_LOG_MLQUEUE(3, printk("queuecommand : command too long.\n"));
				SCpnt->result = (DID_ABORT << 16);
				spin_lock_irqsave(&io_request_lock, flags);
				scsi_done(SCpnt);
				spin_unlock_irqrestore(&io_request_lock, flags);
				rtn = 1;
			}
		} else {
			/*
			 * Before we queue this command, check if the command
			 * length exceeds what the host adapter can handle.
			 */
			if (CDB_SIZE(SCpnt) <= SCpnt->host->max_cmd_len) {
				spin_lock_irqsave(&io_request_lock, flags);
				host->hostt->queuecommand(SCpnt, scsi_old_done);
				spin_unlock_irqrestore(&io_request_lock, flags);
			} else {
				SCSI_LOG_MLQUEUE(3, printk("queuecommand : command too long.\n"));
				SCpnt->result = (DID_ABORT << 16);
				spin_lock_irqsave(&io_request_lock, flags);
				scsi_old_done(SCpnt);
				spin_unlock_irqrestore(&io_request_lock, flags);
				rtn = 1;
			}
		}
	} else {
		int temp;

		SCSI_LOG_MLQUEUE(3, printk("command() :  routine at %p\n", host->hostt->command));
                spin_lock_irqsave(&io_request_lock, flags);
		temp = host->hostt->command(SCpnt);
		SCpnt->result = temp;
#ifdef DEBUG_DELAY
                spin_unlock_irqrestore(&io_request_lock, flags);
		clock = jiffies + 4 * HZ;
		while (time_before(jiffies, clock)) {
			barrier();
			cpu_relax();
		}
		printk("done(host = %d, result = %04x) : routine at %p\n",
		       host->host_no, temp, host->hostt->command);
                spin_lock_irqsave(&io_request_lock, flags);
#endif
		if (host->hostt->use_new_eh_code) {
			scsi_done(SCpnt);
		} else {
			scsi_old_done(SCpnt);
		}
                spin_unlock_irqrestore(&io_request_lock, flags);
	}
	SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
	return rtn;
}

devfs_handle_t scsi_devfs_handle;

/*
 * scsi_do_cmd sends all the commands out to the low-level driver.  It
 * handles the specifics required for each low level driver - ie queued
 * or non queued.  It also prevents conflicts when different high level
 * drivers go for the same host at the same time.
 */

void scsi_wait_req (Scsi_Request * SRpnt, const void *cmnd ,
 		  void *buffer, unsigned bufflen, 
 		  int timeout, int retries)
{
	DECLARE_COMPLETION(wait);
	request_queue_t *q = &SRpnt->sr_device->request_queue;
	
	SRpnt->sr_request.waiting = &wait;
	SRpnt->sr_request.rq_status = RQ_SCSI_BUSY;
	scsi_do_req (SRpnt, (void *) cmnd,
		buffer, bufflen, scsi_wait_done, timeout, retries);
	generic_unplug_device(q);
	wait_for_completion(&wait);
	SRpnt->sr_request.waiting = NULL;
	if( SRpnt->sr_command != NULL )
	{
		scsi_release_command(SRpnt->sr_command);
		SRpnt->sr_command = NULL;
	}

}
 
/*
 * Function:    scsi_do_req
 *
 * Purpose:     Queue a SCSI request
 *
 * Arguments:   SRpnt     - command descriptor.
 *              cmnd      - actual SCSI command to be performed.
 *              buffer    - data buffer.
 *              bufflen   - size of data buffer.
 *              done      - completion function to be run.
 *              timeout   - how long to let it run before timeout.
 *              retries   - number of retries we allow.
 *
 * Lock status: With the new queueing code, this is SMP-safe, and no locks
 *              need be held upon entry.   The old queueing code the lock was
 *              assumed to be held upon entry.
 *
 * Returns:     Nothing.
 *
 * Notes:       Prior to the new queue code, this function was not SMP-safe.
 *              Also, this function is now only used for queueing requests
 *              for things like ioctls and character device requests - this
 *              is because we essentially just inject a request into the
 *              queue for the device. Normal block device handling manipulates
 *              the queue directly.
 */
void scsi_do_req(Scsi_Request * SRpnt, const void *cmnd,
	      void *buffer, unsigned bufflen, void (*done) (Scsi_Cmnd *),
		 int timeout, int retries)
{
	Scsi_Device * SDpnt = SRpnt->sr_device;
	struct Scsi_Host *host = SDpnt->host;

	ASSERT_LOCK(&io_request_lock, 0);

	SCSI_LOG_MLQUEUE(4,
			 {
			 int i;
			 int target = SDpnt->id;
			 int size = COMMAND_SIZE(((const unsigned char *)cmnd)[0]);
			 printk("scsi_do_req (host = %d, channel = %d target = %d, "
		    "buffer =%p, bufflen = %d, done = %p, timeout = %d, "
				"retries = %d)\n"
				"command : ", host->host_no, SDpnt->channel, target, buffer,
				bufflen, done, timeout, retries);
			 for (i	 = 0; i < size; ++i)
			 	printk("%02x  ", ((unsigned char *) cmnd)[i]);
			 	printk("\n");
			 });

	if (!host) {
		panic("Invalid or not present host.\n");
	}

	/*
	 * If the upper level driver is reusing these things, then
	 * we should release the low-level block now.  Another one will
	 * be allocated later when this request is getting queued.
	 */
	if( SRpnt->sr_command != NULL )
	{
		scsi_release_command(SRpnt->sr_command);
		SRpnt->sr_command = NULL;
	}

	/*
	 * We must prevent reentrancy to the lowlevel host driver.  This prevents
	 * it - we enter a loop until the host we want to talk to is not busy.
	 * Race conditions are prevented, as interrupts are disabled in between the
	 * time we check for the host being not busy, and the time we mark it busy
	 * ourselves.
	 */


	/*
	 * Our own function scsi_done (which marks the host as not busy, disables
	 * the timeout counter, etc) will be called by us or by the
	 * scsi_hosts[host].queuecommand() function needs to also call
	 * the completion function for the high level driver.
	 */

	memcpy((void *) SRpnt->sr_cmnd, (const void *) cmnd,