scsi.c

基于组件方式开发操作系统的OSKIT源代码

      scsi_bh_queue_head = NULL;
      
      if( SCpnt == NULL ) {
          spin_unlock_irqrestore(&io_request_lock, flags);
          return;
          }
      
      SCnext = SCpnt->bh_next;
      
      for(; SCpnt; SCpnt = SCnext)
      {
          SCnext = SCpnt->bh_next;
          
          switch( scsi_decide_disposition(SCpnt) )
          {
          case SUCCESS:
              /*
               * Add to BH queue.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command finished %d %d 0x%x\n", SCpnt->host->host_busy,
                     SCpnt->host->host_failed,
                     SCpnt->result));
              
              scsi_finish_command(SCpnt);
              break;
          case NEEDS_RETRY:
              /*
               * We only come in here if we want to retry a command.  The
               * test to see whether the command should be retried should be
               * keeping track of the number of tries, so we don't end up looping,
               * of course.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command needs retry %d %d 0x%x\n", SCpnt->host->host_busy,
                     SCpnt->host->host_failed, SCpnt->result));
              
              scsi_retry_command(SCpnt);
              break;
          case ADD_TO_MLQUEUE:
              /* 
               * This typically happens for a QUEUE_FULL message -
               * typically only when the queue depth is only
               * approximate for a given device.  Adding a command
               * to the queue for the device will prevent further commands
               * from being sent to the device, so we shouldn't end up
               * with tons of things being sent down that shouldn't be.
               */
              scsi_mlqueue_insert(SCpnt, SCSI_MLQUEUE_DEVICE_BUSY);
              break;
          default:
              /*
               * Here we have a fatal error of some sort.  Turn it over to
               * the error handler.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command failed %p %x active=%d busy=%d failed=%d\n", 
                                           SCpnt, SCpnt->result,
                                           atomic_read(&SCpnt->host->host_active),
                                           SCpnt->host->host_busy,
                                           SCpnt->host->host_failed));
              
              /*
               * Dump the sense information too.
               */
              if ((status_byte (SCpnt->result) & CHECK_CONDITION) != 0)
              {
                  SCSI_LOG_MLCOMPLETE(3,print_sense("bh",SCpnt));
              }


              if( SCpnt->host->eh_wait != NULL )
              {
                  SCpnt->host->host_failed++;
                  SCpnt->owner = SCSI_OWNER_ERROR_HANDLER;
                  SCpnt->state = SCSI_STATE_FAILED;
                  SCpnt->host->in_recovery = 1;
                  /*
                   * 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->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);
                  }
              }
              else
              {
                  /*
                   * We only get here if the error recovery thread has died.
                   */
                  scsi_finish_command(SCpnt);
              }
          }
      } /* for(; SCpnt...) */

  } /* while(1==1) */

  spin_unlock_irqrestore(&io_request_lock, flags);

}

/*
 * Function:    scsi_retry_command
 *
 * Purpose:     Send a command back to the low level to be retried.
 *
 * Notes:       This command is always executed in the context of the
 *              bottom half handler, or the error handler thread. Low
 *              level drivers should not become re-entrant as a result of
 *              this.
 */
int
scsi_retry_command(Scsi_Cmnd * SCpnt)
{
  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->result = 0;
  memset ((void *) SCpnt->sense_buffer, 0, sizeof SCpnt->sense_buffer);
  return internal_cmnd (SCpnt);
}

/*
 * Function:    scsi_finish_command
 *
 * Purpose:     Pass command off to upper layer for finishing of I/O
 *              request, waking processes that are waiting on results,
 *              etc.
 */
void
scsi_finish_command(Scsi_Cmnd * SCpnt)
{
    struct Scsi_Host * host;
    Scsi_Device * device;

    host = SCpnt->host;
    device = SCpnt->device;

    host->host_busy--; /* Indicate that we are free */
    device->device_busy--; /* Decrement device usage counter. */
  
    if (host->block && host->host_busy == 0) 
    {
        host_active = NULL;
        
        /* For block devices "wake_up" is done in end_scsi_request */
        if (!SCSI_BLK_MAJOR(MAJOR(SCpnt->request.rq_dev))) {
            struct Scsi_Host * next;
            
            for (next = host->block; next != host; next = next->block)
                wake_up(&next->host_wait);
        }
        
    }
  
    /*
     * Now try and drain the mid-level queue if any commands have been
     * inserted.  Check to see whether the queue even has anything in
     * it first, as otherwise this is useless overhead.
     */
    if( SCpnt->host->pending_commands != NULL )
    {
        scsi_mlqueue_finish(SCpnt->host, SCpnt->device);
    }

    wake_up(&host->host_wait);
    
    /*
     * If we have valid sense information, then some kind of recovery
     * must have taken place.  Make a note of this.
     */
    if( scsi_sense_valid(SCpnt) )
    {
        SCpnt->result |= (DRIVER_SENSE << 24);
    }
    
    SCSI_LOG_MLCOMPLETE(3,printk("Notifying upper driver of completion for device %d %x\n",
                                     SCpnt->device->id, SCpnt->result));
    
    SCpnt->owner = SCSI_OWNER_HIGHLEVEL;
    SCpnt->state = SCSI_STATE_FINISHED;

    /* We can get here with use_sg=0, causing a panic in the upper level (DB) */
    SCpnt->use_sg = SCpnt->old_use_sg;

    SCpnt->done (SCpnt);
}

#ifdef CONFIG_MODULES
static int scsi_register_host(Scsi_Host_Template *);
static void scsi_unregister_host(Scsi_Host_Template *);
#endif

void *scsi_malloc(unsigned int len)
{
    unsigned int nbits, mask;
    int i, j;
    if(len % SECTOR_SIZE != 0 || len > PAGE_SIZE)
	return NULL;

    nbits = len >> 9;
    mask = (1 << nbits) - 1;

    for(i=0;i < dma_sectors / SECTORS_PER_PAGE; i++)
	for(j=0; j<=SECTORS_PER_PAGE - nbits; j++){
	    if ((dma_malloc_freelist[i] & (mask << j)) == 0){
		dma_malloc_freelist[i] |= (mask << j);
		scsi_dma_free_sectors -= nbits;
#ifdef DEBUG
                SCSI_LOG_MLQUEUE(3,printk("SMalloc: %d %p [From:%p]\n",len, dma_malloc_pages[i] + (j << 9)));
		printk("SMalloc: %d %p [From:%p]\n",len, dma_malloc_pages[i] + (j << 9));
#endif
		return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9));
	    }
	}
    return NULL;  /* Nope.  No more */
}

int scsi_free(void *obj, unsigned int len)
{
    unsigned int page, sector, nbits, mask;

#ifdef DEBUG
    unsigned long ret = 0;

#ifdef __mips__
    __asm__ __volatile__ ("move\t%0,$31":"=r"(ret));
#else
   ret = __builtin_return_address(0);
#endif
    printk("scsi_free %p %d\n",obj, len);
    SCSI_LOG_MLQUEUE(3,printk("SFree: %p %d\n",obj, len));
#endif

    for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) {
        unsigned long page_addr = (unsigned long) dma_malloc_pages[page];
        if ((unsigned long) obj >= page_addr &&
	    (unsigned long) obj <  page_addr + PAGE_SIZE)
	{
	    sector = (((unsigned long) obj) - page_addr) >> 9;

            nbits = len >> 9;
            mask = (1 << nbits) - 1;

            if ((mask << sector) >= (1 << SECTORS_PER_PAGE))
                panic ("scsi_free:Bad memory alignment");

            if((dma_malloc_freelist[page] &
                (mask << sector)) != (mask<<sector)){
#ifdef DEBUG
		printk("scsi_free(obj=%p, len=%d) called from %08lx\n",
                       obj, len, ret);
#endif
                panic("scsi_free:Trying to free unused memory");
            }
            scsi_dma_free_sectors += nbits;
            dma_malloc_freelist[page] &= ~(mask << sector);
            return 0;
	}
    }
    panic("scsi_free:Bad offset");
}


int scsi_loadable_module_flag; /* Set after we scan builtin drivers */

void * scsi_init_malloc(unsigned int size, int gfp_mask)
{
    void * retval;

    /*
     * For buffers used by the DMA pool, we assume page aligned 
     * structures.
     */
    if ((size % PAGE_SIZE) == 0) {
	int order, a_size;
	for (order = 0, a_size = PAGE_SIZE;
             a_size < size; order++, a_size <<= 1)
            ;
	retval = (void *) __get_free_pages(gfp_mask | GFP_DMA, order);
    } else
	retval = kmalloc(size, gfp_mask);

    if (retval)
	memset(retval, 0, size);
    return retval;
}


void scsi_init_free(char * ptr, unsigned int size)
{
    /*
     * We need this special code here because the DMA pool assumes
     * page aligned data.  Besides, it is wasteful to allocate
     * page sized chunks with kmalloc.
     */
    if ((size % PAGE_SIZE) == 0) {
    	int order, a_size;

	for (order = 0, a_size = PAGE_SIZE;
	     a_size < size; order++, a_size <<= 1)
	    ;
	free_pages((unsigned long)ptr, order);
    } else
	kfree(ptr);
}

void scsi_build_commandblocks(Scsi_Device * SDpnt)
{
    struct Scsi_Host *host = SDpnt->host;
    int j;
    Scsi_Cmnd * SCpnt;

    if (SDpnt->queue_depth == 0)
        SDpnt->queue_depth = host->cmd_per_lun;
    SDpnt->device_queue = NULL;

    for(j=0;j<SDpnt->queue_depth;j++){
        SCpnt = (Scsi_Cmnd *)
              scsi_init_malloc(sizeof(Scsi_Cmnd),
                               GFP_ATOMIC |
                               (host->unchecked_isa_dma ? GFP_DMA : 0));
	if (NULL == SCpnt)
	    break; /* If not, the next line will oops ... */
        memset(&SCpnt->eh_timeout, 0, sizeof(SCpnt->eh_timeout));
	SCpnt->host                      = host;
	SCpnt->device                    = SDpnt;
	SCpnt->target                    = SDpnt->id;
	SCpnt->lun                       = SDpnt->lun;
	SCpnt->channel                   = SDpnt->channel;
	SCpnt->request.rq_status         = RQ_INACTIVE;
        SCpnt->host_wait                 = FALSE;
        SCpnt->device_wait               = FALSE;
	SCpnt->use_sg                    = 0;
	SCpnt->old_use_sg                = 0;
	SCpnt->old_cmd_len               = 0;
	SCpnt->underflow                 = 0;
	SCpnt->transfersize              = 0;
	SCpnt->serial_number             = 0;
	SCpnt->serial_number_at_timeout  = 0;
	SCpnt->host_scribble             = NULL;
	SCpnt->next                      = SDpnt->device_queue;
	SDpnt->device_queue              = SCpnt;
        SCpnt->state                     = SCSI_STATE_UNUSED;
        SCpnt->owner                     = SCSI_OWNER_NOBODY;
    }
    if (j < SDpnt->queue_depth) { /* low on space (D.Gilbert 990424) */
	printk("scsi_build_commandblocks: want=%d, space for=%d blocks\n",
	       SDpnt->queue_depth, j);
	SDpnt->queue_depth = j;
	SDpnt->has_cmdblocks = (0 != j);
    }
    else
	SDpnt->has_cmdblocks = 1;
}

#ifndef MODULE /* { */
/*
 * scsi_dev_init() is our initialization routine, which in turn calls host
 * initialization, bus scanning, and sd/st initialization routines.
 * This is only used at boot time.
 */
__initfunc(int scsi_dev_init(void))
{
    Scsi_Device * SDpnt;
    struct Scsi_Host * shpnt;
    struct Scsi_Device_Template * sdtpnt;
#ifdef FOO_ON_YOU
    return;
#endif

    /* Yes we're here... */
#if CONFIG_PROC_FS
    dispatch_scsi_info_ptr = dispatch_scsi_info;
#endif

    /* Init a few things so we can "malloc" memory. */
    scsi_loadable_module_flag = 0;

    /* Register the /proc/scsi/scsi entry */
#if CONFIG_PROC_FS
    proc_scsi_register(0, &proc_scsi_scsi);
#endif

    /* initialize all hosts */
    scsi_init();

    /*
     * This is where the processing takes place for most everything
     * when commands are completed.  Until we do this, we will not be able
     * to queue any commands.
     */
    init_bh(SCSI_BH, scsi_bottom_half_handler);

    for (shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next) {
	scan_scsis(shpnt,0,0,0,0);           /* scan for scsi devices */
	if (shpnt->select_queue_depths != NULL)
	    (shpnt->select_queue_depths)(shpnt, shpnt->host_queue);
    }

    printk("scsi : detected ");
    for (sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
	if (sdtpnt->dev_noticed && sdtpnt->name)
	    printk("%d SCSI %s%s ", sdtpnt->dev_noticed, sdtpnt->name,
		   (sdtpnt->dev_noticed != 1) ? "s" : "");
    printk("total.\n");

    for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
	if(sdtpnt->init && s