sg.c

来自「linux 内核源代码」· C语言 代码 · 共 2,357 行 · 第 1/5 页

			num_xfer = schp->bufflen;
	}
	if ((num_xfer <= 0) || (schp->dio_in_use) ||
	    (new_interface
	     && ((SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO) & 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 (!access_ok(VERIFY_READ, hp->dxferp, SZ_SG_IOVEC * onum))
			return -EFAULT;
	} else
		onum = 1;

	ksglen = sg->length;
	p = page_address(sg_page(sg));
	for (j = 0, k = 0; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 1, &usglen, &up);
		if (res)
			return res;

		for (; p; sg = sg_next(sg), ksglen = sg->length,
		     p = page_address(sg_page(sg))) {
			if (usglen <= 0)
				break;
			if (ksglen > usglen) {
				if (usglen >= num_xfer) {
					if (__copy_from_user(p, up, num_xfer))
						return -EFAULT;
					return 0;
				}
				if (__copy_from_user(p, up, usglen))
					return -EFAULT;
				p += usglen;
				ksglen -= usglen;
				break;
			} else {
				if (ksglen >= num_xfer) {
					if (__copy_from_user(p, up, num_xfer))
						return -EFAULT;
					return 0;
				}
				if (__copy_from_user(p, up, ksglen))
					return -EFAULT;
				up += ksglen;
				usglen -= ksglen;
			}
			++k;
			if (k >= schp->k_use_sg)
				return 0;
		}
	}

	return 0;
}

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

	if (0 == sg_num) {
		if (wr_xf && ('\0' == hp->interface_id))
			count = (int) hp->flags;	/* holds "old" input_size */
		else
			count = num_xfer;
	} else {
		sg_iovec_t iovec;
		if (__copy_from_user(&iovec, p + ind*SZ_SG_IOVEC, SZ_SG_IOVEC))
			return -EFAULT;
		p = iovec.iov_base;
		count = (int) iovec.iov_len;
	}
	if (!access_ok(wr_xf ? VERIFY_READ : VERIFY_WRITE, p, count))
		return -EFAULT;
	if (up)
		*up = p;
	if (countp)
		*countp = count;
	return 0;
}

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 > 0)) {
		struct scatterlist *sg = schp->buffer;

		if (schp->dio_in_use) {
#ifdef SG_ALLOW_DIO_CODE
			st_unmap_user_pages(sg, schp->k_use_sg, TRUE);
#endif
		} else {
			int k;

			for (k = 0; (k < schp->k_use_sg) && sg_page(sg);
			     ++k, sg = sg_next(sg)) {
				SCSI_LOG_TIMEOUT(5, printk(
				    "sg_remove_scat: k=%d, pg=0x%p, len=%d\n",
				    k, sg_page(sg), sg->length));
				sg_page_free(sg_page(sg), sg->length);
			}
		}
		kfree(schp->buffer);
	}
	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;
	struct scatterlist *sg = schp->buffer;
	int num_xfer = 0;
	int j, k, onum, usglen, ksglen, res;
	int iovec_count = (int) hp->iovec_count;
	int dxfer_dir = hp->dxfer_direction;
	unsigned char *p;
	unsigned char __user *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) || (schp->dio_in_use) ||
	    (new_interface
	     && ((SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO) & 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 (!access_ok(VERIFY_READ, hp->dxferp, SZ_SG_IOVEC * onum))
			return -EFAULT;
	} else
		onum = 1;

	p = page_address(sg_page(sg));
	ksglen = sg->length;
	for (j = 0, k = 0; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 0, &usglen, &up);
		if (res)
			return res;

		for (; p; sg = sg_next(sg), ksglen = sg->length,
		     p = page_address(sg_page(sg))) {
			if (usglen <= 0)
				break;
			if (ksglen > usglen) {
				if (usglen >= num_xfer) {
					if (__copy_to_user(up, p, num_xfer))
						return -EFAULT;
					return 0;
				}
				if (__copy_to_user(up, p, usglen))
					return -EFAULT;
				p += usglen;
				ksglen -= usglen;
				break;
			} else {
				if (ksglen >= num_xfer) {
					if (__copy_to_user(up, p, num_xfer))
						return -EFAULT;
					return 0;
				}
				if (__copy_to_user(up, p, ksglen))
					return -EFAULT;
				up += ksglen;
				usglen -= ksglen;
			}
			++k;
			if (k >= schp->k_use_sg)
				return 0;
		}
	}

	return 0;
}

static int
sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
{
	Sg_scatter_hold *schp = &srp->data;
	struct scatterlist *sg = schp->buffer;
	int k, num;

	SCSI_LOG_TIMEOUT(4, printk("sg_read_oxfer: num_read_xfer=%d\n",
				   num_read_xfer));
	if ((!outp) || (num_read_xfer <= 0))
		return 0;

	for (k = 0; (k < schp->k_use_sg) && sg_page(sg); ++k, sg = sg_next(sg)) {
		num = sg->length;
		if (num > num_read_xfer) {
			if (__copy_to_user(outp, page_address(sg_page(sg)),
					   num_read_xfer))
				return -EFAULT;
			break;
		} else {
			if (__copy_to_user(outp, page_address(sg_page(sg)),
					   num))
				return -EFAULT;
			num_read_xfer -= num;
			if (num_read_xfer <= 0)
				break;
			outp += num;
		}
	}

	return 0;
}

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_indirect(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;
	struct scatterlist *sg = rsv_schp->buffer;
	int k, num, rem;

	srp->res_used = 1;
	SCSI_LOG_TIMEOUT(4, printk("sg_link_reserve: size=%d\n", size));
	rem = size;

	for (k = 0; k < rsv_schp->k_use_sg; ++k, sg = sg_next(sg)) {
		num = sg->length;
		if (rem <= num) {
			sfp->save_scat_len = num;
			sg->length = 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->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"));
}

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 *sg = rsv_schp->buffer;

		if (sfp->save_scat_len > 0)
			(sg + (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_scat_len = 0;
	srp->res_used = 0;
}

static Sg_request *
sg_get_rq_mark(Sg_fd * sfp, int pack_id)
{
	Sg_request *resp;
	unsigned long iflags;

	write_lock_irqsave(&sfp->rq_list_lock, iflags);
	for (resp = sfp->headrp; resp; resp = resp->nextrp) {
		/* look for requests that are ready + not SG_IO owned */
		if ((1 == resp->done) && (!resp->sg_io_owned) &&
		    ((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
			resp->done = 2;	/* guard against other readers */
			break;
		}
	}
	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
	return resp;
}

#ifdef CONFIG_SCSI_PROC_FS
static Sg_request *
sg_get_nth_request(Sg_fd * sfp, int nth)
{
	Sg_request *resp;
	unsigned long iflags;
	int k;

	read_lock_irqsave(&sfp->rq_list_lock, iflags);
	for (k = 0, resp = sfp->headrp; resp && (k < nth);
	     ++k, resp = resp->nextrp) ;
	read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
	return resp;
}
#endif

/* always adds to end of list */
static Sg_request *
sg_add_request(Sg_fd * sfp)
{
	int k;
	unsigned long iflags;
	Sg_request *resp;
	Sg_request *rp = sfp->req_arr;

	write_lock_irqsave(&sfp->rq_list_lock, iflags);
	resp = sfp->headrp;
	if (!resp) {
		memset(rp, 0, sizeof (Sg_request));
		rp->parentfp = sfp;
		resp = rp;
		sfp->headrp = resp;
	} else {
		if (0 == sfp->cmd_q)
			resp = NULL;	/* command queuing disallowed */
		else {
			for (k = 0; k < SG_MAX_QUEUE; ++k, ++rp) {
				if (!rp->parentfp)
					break;
			}
			if (k < SG_MAX_QUEUE) {
				memset(rp, 0, sizeof (Sg_request));
				rp->parentfp = sfp;
				while (resp->nextrp)
					resp = resp->nextrp;
				resp->nextrp = rp;
				resp = rp;
			} else
				resp = NULL;
		}
	}
	if (resp) {
		resp->nextrp = NULL;
		resp->header.duration = jiffies_to_msecs(jiffies);
	}
	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
	return resp;
}

/* Return of 1 for found; 0 for not found */
static int
sg_remove_request(Sg_fd * sfp, Sg_request * srp)
{
	Sg_request *prev_rp;
	Sg_request *rp;
	unsigned long iflags;
	int res = 0;

	if ((!sfp) || (!srp) || (!sfp->headrp))
		return res;
	write_lock_irqsave(&sfp->rq_list_lock, iflags);
	prev_rp = sfp->headrp;
	if (srp == prev_rp) {
		sfp->headrp = prev_rp->nextrp;
		prev_rp->parentfp = NULL;
		res = 1;
	} else {
		while ((rp = prev_rp->nextrp)) {
			if (srp == rp) {
				prev_rp->nextrp = rp->nextrp;
				rp->parentfp = NULL;
				res = 1;
				break;
			}
			prev_rp = rp;
		}
	}
	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
	return res;
}

#ifdef CONFIG_SCSI_PROC_FS
static Sg_fd *
sg_get_nth_sfp(Sg_device * sdp, int nth)
{
	Sg_fd *resp;
	unsigned long iflags;
	int k;

	read_lock_irqsave(&sg_index_lock, iflags);
	for (k = 0, resp = sdp->headfp; resp && (k < nth);
	     ++k, resp = resp->nextfp) ;
	read_unlock_irqrestore(&sg_index_lock, iflags);
	return resp;
}
#endif

static Sg_fd *
sg_add_sfp(Sg_device * sdp, int dev)
{
	Sg_fd *sfp;
	unsigned long iflags;
	int bufflen;

	sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
	if (!sfp)
		return NULL;

	init_waitqueue_head(&sfp->read_wait);
	rwlock_init(&sfp->rq_list_lock);

	sfp->timeout = SG_DEFAULT_TIMEOUT;
	sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
	sfp->force_packid = SG_DEF_FORCE_PACK_ID;
	sfp->low_dma = (SG_DEF_FORCE_LOW_DMA == 0) ?
	    sdp->device->host->unchecked_isa_dma : 1;
	sfp->cmd_q = SG_DEF_COMMAND_Q;
	sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
	sfp->parentdp = sdp;
	write_lock_irqsave(&sg_index_lock, iflags);
	if (!sdp->headfp)
		sdp->headfp = sfp;
	else {			/* add to tail of existing list */
		Sg_fd *pfp = sdp->headfp;
		while (pfp->nextfp)
			pfp = pfp->nextfp;
		pfp->nextfp = sfp;
	}
	write_unlock_irqrestore(&sg_index_lock, iflags);
	SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp: sfp=0x%p\n", sfp));
	if (unlikely(sg_big_buff != def_reserved_size))
		sg_big_buff = def_reserved_size;

	bufflen = min_t(int, sg_big_buff,
			sdp->device->request_queue->max_sectors * 512);
	sg_build_reserve(sfp, bufflen);
	SCSI_LOG_TIMEOUT(3, printk("sg_add_sfp:   bufflen=%d, k_use_sg=%d\n",
			   sfp->reserve.bufflen, sfp->reserve.k_use_sg));
	return sfp;
}

static void
__sg_remove_sfp(Sg_dev