sg.c

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	if (mx_sc_elems < 0)
	    return mx_sc_elems; /* most likely -ENOMEM */
	mem_src_arr = schp->buffer +
		      (mx_sc_elems * sizeof(struct scatterlist));

	for (k = 0, sclp = schp->buffer, rem_sz = blk_size;
	     (k < sg_tablesize) && (rem_sz > 0) && (k < mx_sc_elems);
             ++k, rem_sz -= ret_sz, ++sclp) {
	    if (first)
                first = 0;
            else {
                num = (rem_sz > SG_SCATTER_SZ) ? SG_SCATTER_SZ : rem_sz;
                mem_src = SG_HEAP_PAGE;
                p = sg_malloc(sfp, num, &ret_sz, &mem_src);
                if (! p)
                    break;
            }
            sclp->address = p;
            sclp->length = ret_sz;
	    mem_src_arr[k] = mem_src;

	    SCSI_LOG_TIMEOUT(5,
		printk("sg_build_build: k=%d, a=0x%p, len=%d, ms=%d\n",
                k, sclp->address, ret_sz, mem_src));
        } /* end of for loop */
	schp->k_use_sg = k;
	SCSI_LOG_TIMEOUT(5,
	    printk("sg_build_indi: k_use_sg=%d, rem_sz=%d\n", k, rem_sz));
        schp->bufflen = blk_size;
        if (rem_sz > 0)   /* must have failed */
            return -ENOMEM;
    }
    return 0;
}

static int sg_write_xfer(Sg_request * srp)
{
    sg_io_hdr_t * hp = &srp->header;
    Sg_scatter_hold * schp = &srp->data;
    int num_xfer = 0;
    int j, k, onum, usglen, ksglen, res, ok;
    int iovec_count = (int)hp->iovec_count;
    int dxfer_dir = hp->dxfer_direction;
    unsigned char * p;
    unsigned char * up;
    int new_interface = ('\0' == hp->interface_id) ? 0 : 1;

    if ((SG_DXFER_UNKNOWN == dxfer_dir) || (SG_DXFER_TO_DEV == dxfer_dir) ||
	(SG_DXFER_TO_FROM_DEV == dxfer_dir)) {
	num_xfer = (int)(new_interface ?  hp->dxfer_len : hp->flags);
	if (schp->bufflen < num_xfer)
	    num_xfer = schp->bufflen;
    }
    if ((num_xfer <= 0) || (new_interface && (SG_FLAG_NO_DXFER & hp->flags)))
	return 0;

    SCSI_LOG_TIMEOUT(4,
	 printk("sg_write_xfer: num_xfer=%d, iovec_count=%d, k_use_sg=%d\n",
		num_xfer, iovec_count, schp->k_use_sg));
    if (iovec_count) {
	onum = iovec_count;
	if ((k = verify_area(VERIFY_READ, hp->dxferp,
			     size_sg_iovec * onum)))
	    return k;
    }
    else
	onum = 1;

    if (0 == schp->k_use_sg) {  /* kernel has single buffer */
	if (SG_USER_MEM != schp->buffer_mem_src) { /* else nothing to do */

	    for (j = 0, p = schp->buffer; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 1, &usglen, &up);
		if (res) return res;
		usglen = (num_xfer > usglen) ? usglen : num_xfer;
		__copy_from_user(p, up, usglen);
		p += usglen;
		num_xfer -= usglen;
		if (num_xfer <= 0)
		    return 0;
            }
	}
    }
    else {      /* kernel using scatter gather list */
	struct scatterlist * sclp = (struct scatterlist *)schp->buffer;
	char * mem_src_arr = sg_get_sgat_msa(schp);
	ksglen = (int)sclp->length;
	p = sclp->address;

	for (j = 0, k = 0; j < onum; ++j) {
	    res = sg_u_iovec(hp, iovec_count, j, 1, &usglen, &up);
	    if (res) return res;

	    for (; (k < schp->k_use_sg) && p;
		 ++k, ++sclp, ksglen = (int)sclp->length, p = sclp->address) {
		ok = (SG_USER_MEM != mem_src_arr[k]);
		if (usglen <= 0)
		    break;
		if (ksglen > usglen) {
		    if (usglen >= num_xfer) {
			if (ok) __copy_from_user(p, up, num_xfer);
			return 0;
		    }
		    if (ok) __copy_from_user(p, up, usglen);
		    p += usglen;
		    ksglen -= usglen;
                    break;
		}
		else {
		    if (ksglen >= num_xfer) {
			if (ok) __copy_from_user(p, up, num_xfer);
			return 0;
		    }
		    if (ok) __copy_from_user(p, up, ksglen);
		    up += ksglen;
		    usglen -= ksglen;
		}
            }
        }
    }
    return 0;
}

static int sg_u_iovec(sg_io_hdr_t * hp, int sg_num, int ind,
		      int wr_xf, int * countp, unsigned char ** up)
{
    int num_xfer = (int)hp->dxfer_len;
    unsigned char * p;
    int count, k;
    sg_iovec_t u_iovec;

    if (0 == sg_num) {
	p = (unsigned char *)hp->dxferp;
	if (wr_xf && ('\0' == hp->interface_id))
	    count = (int)hp->flags; /* holds "old" input_size */
	else
	    count = num_xfer;
    }
    else {
	__copy_from_user(&u_iovec,
			 (unsigned char *)hp->dxferp + (ind * size_sg_iovec),
			 size_sg_iovec);
	p = (unsigned char *)u_iovec.iov_base;
	count = (int)u_iovec.iov_len;
    }
    if ((k = verify_area(wr_xf ? VERIFY_READ : VERIFY_WRITE, p, count)))
	return k;
    if (up) *up = p;
    if (countp) *countp = count;
    return 0;
}

static char * sg_get_sgat_msa(Sg_scatter_hold * schp)
{
    int elem_sz = sizeof(struct scatterlist) + sizeof(char);
    int mx_sc_elems = (schp->sglist_len / elem_sz) - 1;
    return schp->buffer + (sizeof(struct scatterlist) * mx_sc_elems);
}

static void sg_remove_scat(Sg_scatter_hold * schp)
{
    SCSI_LOG_TIMEOUT(4, printk("sg_remove_scat: k_use_sg=%d\n",
			       schp->k_use_sg));
    if (schp->buffer && schp->sglist_len) {
        int k, mem_src;
        struct scatterlist * sclp = (struct scatterlist *)schp->buffer;
	char * mem_src_arr = sg_get_sgat_msa(schp);

	for (k = 0; (k < schp->k_use_sg) && sclp->address; ++k, ++sclp) {
	    mem_src = mem_src_arr[k];
	    SCSI_LOG_TIMEOUT(5,
		printk("sg_remove_scat: k=%d, a=0x%p, len=%d, ms=%d\n",
                       k, sclp->address, sclp->length, mem_src));
            sg_free(sclp->address, sclp->length, mem_src);
            sclp->address = NULL;
            sclp->length = 0;
        }
	sg_free(schp->buffer, schp->sglist_len, schp->buffer_mem_src);
    }
    else if (schp->buffer)
	sg_free(schp->buffer, schp->b_malloc_len, schp->buffer_mem_src);
    memset(schp, 0, sizeof(*schp));
}

static int sg_read_xfer(Sg_request * srp)
{
    sg_io_hdr_t * hp = &srp->header;
    Sg_scatter_hold * schp = &srp->data;
    int num_xfer = 0;
    int j, k, onum, usglen, ksglen, res, ok;
    int iovec_count = (int)hp->iovec_count;
    int dxfer_dir = hp->dxfer_direction;
    unsigned char * p;
    unsigned char * up;
    int new_interface = ('\0' == hp->interface_id) ? 0 : 1;

    if ((SG_DXFER_UNKNOWN == dxfer_dir) || (SG_DXFER_FROM_DEV == dxfer_dir) ||
	(SG_DXFER_TO_FROM_DEV == dxfer_dir)) {
	num_xfer =  hp->dxfer_len;
	if (schp->bufflen < num_xfer)
	    num_xfer = schp->bufflen;
    }
    if ((num_xfer <= 0) || (new_interface && (SG_FLAG_NO_DXFER & hp->flags)))
	return 0;

    SCSI_LOG_TIMEOUT(4,
	 printk("sg_read_xfer: num_xfer=%d, iovec_count=%d, k_use_sg=%d\n",
		num_xfer, iovec_count, schp->k_use_sg));
    if (iovec_count) {
	onum = iovec_count;
	if ((k = verify_area(VERIFY_READ, hp->dxferp,
			     size_sg_iovec * onum)))
	    return k;
    }
    else
	onum = 1;

    if (0 == schp->k_use_sg) {  /* kernel has single buffer */
	if (SG_USER_MEM != schp->buffer_mem_src) { /* else nothing to do */

	    for (j = 0, p = schp->buffer; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 0, &usglen, &up);
		if (res) return res;
		usglen = (num_xfer > usglen) ? usglen : num_xfer;
		__copy_to_user(up, p, usglen);
		p += usglen;
		num_xfer -= usglen;
		if (num_xfer <= 0)
		    return 0;
	    }
	}
    }
    else {      /* kernel using scatter gather list */
	struct scatterlist * sclp = (struct scatterlist *)schp->buffer;
	char * mem_src_arr = sg_get_sgat_msa(schp);
	ksglen = (int)sclp->length;
	p = sclp->address;

	for (j = 0, k = 0; j < onum; ++j) {
	    res = sg_u_iovec(hp, iovec_count, j, 0, &usglen, &up);
	    if (res) return res;

	    for (; (k < schp->k_use_sg) && p;
		 ++k, ++sclp, ksglen = (int)sclp->length, p = sclp->address) {
		ok = (SG_USER_MEM != mem_src_arr[k]);
		if (usglen <= 0)
		    break;
		if (ksglen > usglen) {
		    if (usglen >= num_xfer) {
			if (ok) __copy_to_user(up, p, num_xfer);
			return 0;
		    }
		    if (ok) __copy_to_user(up, p, usglen);
		    p += usglen;
		    ksglen -= usglen;
		    break;
		}
		else {
		    if (ksglen >= num_xfer) {
			if (ok) __copy_to_user(up, p, num_xfer);
			return 0;
		    }
		    if (ok) __copy_to_user(up, p, ksglen);
		    up += ksglen;
		    usglen -= ksglen;
		}
	    }
	}
    }
    return 0;
}

static void sg_read_oxfer(Sg_request * srp, char * outp, int num_read_xfer)
{
    Sg_scatter_hold * schp = &srp->data;

    SCSI_LOG_TIMEOUT(4, printk("sg_read_oxfer: num_read_xfer=%d\n",
			       num_read_xfer));
    if ((! outp) || (num_read_xfer <= 0))
        return;
    if(schp->k_use_sg > 0) {
        int k, num;
        struct scatterlist * sclp = (struct scatterlist *)schp->buffer;

	for (k = 0; (k < schp->k_use_sg) && sclp->address; ++k, ++sclp) {
            num = (int)sclp->length;
            if (num > num_read_xfer) {
                __copy_to_user(outp, sclp->address, num_read_xfer);
                break;
            }
            else {
                __copy_to_user(outp, sclp->address, num);
                num_read_xfer -= num;
                if (num_read_xfer <= 0)
                    break;
                outp += num;
            }
        }
    }
    else
        __copy_to_user(outp, schp->buffer, num_read_xfer);
}

static void sg_build_reserve(Sg_fd * sfp, int req_size)
{
    Sg_scatter_hold * schp = &sfp->reserve;

    SCSI_LOG_TIMEOUT(4, printk("sg_build_reserve: req_size=%d\n", req_size));
    do {
        if (req_size < PAGE_SIZE)
            req_size = PAGE_SIZE;
	if (0 == sg_build_indi(schp, sfp, req_size))
            return;
        else
            sg_remove_scat(schp);
        req_size >>= 1; /* divide by 2 */
    } while (req_size >  (PAGE_SIZE / 2));
}

static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size)
{
    Sg_scatter_hold * req_schp = &srp->data;
    Sg_scatter_hold * rsv_schp = &sfp->reserve;

    srp->res_used = 1;
    SCSI_LOG_TIMEOUT(4, printk("sg_link_reserve: size=%d\n", size));
    size = (size + 1) & (~1);    /* round to even for aha1542 */
    if (rsv_schp->k_use_sg > 0) {
        int k, num;
        int rem = size;
        struct scatterlist * sclp = (struct scatterlist *)rsv_schp->buffer;

	for (k = 0; k < rsv_schp->k_use_sg; ++k, ++sclp) {
            num = (int)sclp->length;
            if (rem <= num) {
		if (0 == k) {
		    req_schp->k_use_sg = 0;
		    req_schp->buffer = sclp->address;
		}
		else {
    		    sfp->save_scat_len = num;
    		    sclp->length = (unsigned)rem;
    		    req_schp->k_use_sg = k + 1;
    		    req_schp->sglist_len = rsv_schp->sglist_len;
    		    req_schp->buffer = rsv_schp->buffer;
		}
		req_schp->bufflen = size;
		req_schp->buffer_mem_src = rsv_schp->buffer_mem_src;
		req_schp->b_malloc_len = rsv_schp->b_malloc_len;
		break;
            }
            else
                rem -= num;
        }
	if (k >= rsv_schp->k_use_sg)
	    SCSI_LOG_TIMEOUT(1, printk("sg_link_reserve: BAD size\n"));
    }
    else {
	req_schp->k_use_sg = 0;
        req_schp->bufflen = size;
        req_schp->buffer = rsv_schp->buffer;
	req_schp->buffer_mem_src = rsv_schp->buffer_mem_src;
        req_schp->b_malloc_len = rsv_schp->b_malloc_len;
    }
}

static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp)
{
    Sg_scatter_hold * req_schp = &srp->data;
    Sg_scatter_hold * rsv_schp = &sfp->reserve;

    SCSI_LOG_TIMEOUT(4, printk("sg_unlink_reserve: req->k_use_sg=%d\n",
			       (int)req_schp->k_use_sg));
    if ((rsv_schp->k_use_sg > 0) && (req_schp->k_use_sg > 0)) {
        struct scatterlist * sclp = (struct scatterlist *)rsv_schp->buffer;

	if (sfp->save_scat_len > 0)
	    (sclp + (req_schp->k_use_sg - 1))->length =
                                        (unsigned)sfp->save_scat_len;
        else
            SCSI_LOG_TIMEOUT(1, printk(
			"sg_unlink_reserve: BAD save_scat_len\n"));
    }
    req_schp->k_use_sg = 0;
    req_schp->bufflen = 0;
    req_schp->buffer = NULL;
    req_schp->sglist_len = 0;
    sfp->save_sca