Allocation and Initialization of a scsi_pkt(9S) Structure

The tran_init_pkt(9E) entry point must allocate a scsi_pkt(9S) structure through scsi_hba_pkt_alloc(9F) if pkt is NULL.

scsi_hba_pkt_alloc(9F) allocates space for the following items:

• scsi_pkt(9S)

• SCSI CDB of length cmdlen

• Completion area for SCSI status of length statuslen

• Per-packet target driver private data area of length tgtlen

• Per-packet HBA driver private data area of length hbalen

The scsi_pkt(9S) structure members, including pkt, must be initialized to zero except for the following members:

• pkt_scbp – Status completion

• pkt_cdbp – CDB

• pkt_ha_private – HBA driver private data

• pkt_private – Target driver private data

These members are pointers to memory space where the values of the fields are stored, as shown in the following figure. For more information, refer to scsi_pkt Structure (HBA).

Figure 18–5 scsi_pkt(9S) Structure Pointers

The following example shows allocation and initialization of a scsi_pkt structure.

Example 18–2 HBA Driver Initialization of a SCSI Packet Structure

static struct scsi_pkt                 *
isp_scsi_init_pkt(
    struct scsi_address    *ap,
    struct scsi_pkt        *pkt,
    struct buf             *bp,
    int                    cmdlen,
    int                    statuslen,
    int                    tgtlen,
    int                    flags,
    int                    (*callback)(),
    caddr_t                arg)
{
    struct isp_cmd         *sp;
    struct isp             *isp;
    struct scsi_pkt        *new_pkt;

    ASSERT(callback == NULL_FUNC || callback == SLEEP_FUNC);

    isp = (struct isp *)ap->a_hba_tran->tran_hba_private;
    /*
     * First step of isp_scsi_init_pkt:  pkt allocation
     */
    if (pkt == NULL) {
        pkt = scsi_hba_pkt_alloc(isp->isp_dip, ap, cmdlen,
            statuslen, tgtlen, sizeof (struct isp_cmd),
            callback, arg);
        if (pkt == NULL) {
            return (NULL);
        }

        sp = (struct isp_cmd *)pkt->pkt_ha_private;
        /*
         * Initialize the new pkt
         */
        sp->cmd_pkt         = pkt;
        sp->cmd_flags       = 0;
        sp->cmd_scblen      = statuslen;
        sp->cmd_cdblen      = cmdlen;
        sp->cmd_dmahandle   = NULL;
        sp->cmd_ncookies    = 0;
        sp->cmd_cookie      = 0; 
        sp->cmd_cookiecnt   = 0;
        sp->cmd_nwin        = 0;
        pkt->pkt_address    = *ap;
        pkt->pkt_comp       = (void (*)())NULL;
        pkt->pkt_flags      = 0;
        pkt->pkt_time       = 0;
        pkt->pkt_resid      = 0;
        pkt->pkt_statistics = 0;
        pkt->pkt_reason     = 0;
        new_pkt = pkt;
    } else {
        sp = (struct isp_cmd *)pkt->pkt_ha_private;
        new_pkt = NULL;
    }
    /*
     * Second step of isp_scsi_init_pkt:  dma allocation/move
     */
    if (bp && bp->b_bcount != 0) {
        if (sp->cmd_dmahandle == NULL) {
            if (isp_i_dma_alloc(isp, pkt, bp, flags, callback) == 0) {
                if (new_pkt) {
                    scsi_hba_pkt_free(ap, new_pkt);
                }
                return ((struct scsi_pkt *)NULL);
            }
        } else {
            ASSERT(new_pkt == NULL);
            if (isp_i_dma_move(isp, pkt, bp) == 0) {
                return ((struct scsi_pkt *)NULL);
            }
        }
    }
    return (pkt);
}