sg.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 2,278 行 · 第 1/5 页

	sg_nr_dev++;
	sg_dev_arr[k] = sdp;
	write_unlock_irqrestore(&sg_dev_arr_lock, iflags);
	error = k;

 out:
	if (error < 0)
		kfree(sdp);
	kfree(old_sg_dev_arr);
	return error;

 expand_failed:
	printk(KERN_WARNING "sg_alloc: device array cannot be resized\n");
	error = -ENOMEM;
	goto out;

 overflow:
	write_unlock_irqrestore(&sg_dev_arr_lock, iflags);
	printk(KERN_WARNING
	       "Unable to attach sg device <%d, %d, %d, %d> type=%d, minor "
	       "number exceeds %d\n", scsidp->host->host_no, scsidp->channel,
	       scsidp->id, scsidp->lun, scsidp->type, SG_MAX_DEVS - 1);
	error = -ENODEV;
	goto out;
}

static int
sg_add(struct class_device *cl_dev)
{
	struct scsi_device *scsidp = to_scsi_device(cl_dev->dev);
	struct gendisk *disk;
	Sg_device *sdp = NULL;
	struct cdev * cdev = NULL;
	int error, k;

	disk = alloc_disk(1);
	if (!disk) {
		printk(KERN_WARNING "alloc_disk failed\n");
		return -ENOMEM;
	}
	disk->major = SCSI_GENERIC_MAJOR;

	error = -ENOMEM;
	cdev = cdev_alloc();
	if (!cdev) {
		printk(KERN_WARNING "cdev_alloc failed\n");
		goto out;
	}
	cdev->owner = THIS_MODULE;
	cdev->ops = &sg_fops;

	error = sg_alloc(disk, scsidp);
	if (error < 0) {
		printk(KERN_WARNING "sg_alloc failed\n");
		goto out;
	}
	k = error;
	sdp = sg_dev_arr[k];

	devfs_mk_cdev(MKDEV(SCSI_GENERIC_MAJOR, k),
			S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,
			"%s/generic", scsidp->devfs_name);
	error = cdev_add(cdev, MKDEV(SCSI_GENERIC_MAJOR, k), 1);
	if (error) {
		devfs_remove("%s/generic", scsidp->devfs_name);
		goto out;
	}
	sdp->cdev = cdev;
	if (sg_sysfs_valid) {
		struct class_device * sg_class_member;

		sg_class_member = class_simple_device_add(sg_sysfs_class, 
				MKDEV(SCSI_GENERIC_MAJOR, k), 
				cl_dev->dev, "%s", 
				disk->disk_name);
		if (IS_ERR(sg_class_member))
			printk(KERN_WARNING "sg_add: "
				"class_simple_device_add failed\n");
		class_set_devdata(sg_class_member, sdp);
		error = sysfs_create_link(&scsidp->sdev_gendev.kobj, 
					  &sg_class_member->kobj, "generic");
		if (error)
			printk(KERN_ERR "sg_add: unable to make symlink "
					"'generic' back to sg%d\n", k);
	} else
		printk(KERN_WARNING "sg_add: sg_sys INvalid\n");

	printk(KERN_NOTICE
	       "Attached scsi generic sg%d at scsi%d, channel"
	       " %d, id %d, lun %d,  type %d\n", k,
	       scsidp->host->host_no, scsidp->channel, scsidp->id,
	       scsidp->lun, scsidp->type);

	return 0;

out:
	put_disk(disk);
	if (cdev)
		cdev_del(cdev);
	return error;
}

static void
sg_remove(struct class_device *cl_dev)
{
	struct scsi_device *scsidp = to_scsi_device(cl_dev->dev);
	Sg_device *sdp = NULL;
	unsigned long iflags;
	Sg_fd *sfp;
	Sg_fd *tsfp;
	Sg_request *srp;
	Sg_request *tsrp;
	int k, delay;

	if (NULL == sg_dev_arr)
		return;
	delay = 0;
	write_lock_irqsave(&sg_dev_arr_lock, iflags);
	for (k = 0; k < sg_dev_max; k++) {
		sdp = sg_dev_arr[k];
		if ((NULL == sdp) || (sdp->device != scsidp))
			continue;	/* dirty but lowers nesting */
		if (sdp->headfp) {
			sdp->detached = 1;
			for (sfp = sdp->headfp; sfp; sfp = tsfp) {
				tsfp = sfp->nextfp;
				for (srp = sfp->headrp; srp; srp = tsrp) {
					tsrp = srp->nextrp;
					if (sfp->closed || (0 == srp->done))
						sg_finish_rem_req(srp);
				}
				if (sfp->closed) {
					scsi_device_put(sdp->device);
					__sg_remove_sfp(sdp, sfp);
				} else {
					delay = 1;
					wake_up_interruptible(&sfp->read_wait);
					kill_fasync(&sfp->async_qp, SIGPOLL,
						    POLL_HUP);
				}
			}
			SCSI_LOG_TIMEOUT(3, printk("sg_detach: dev=%d, dirty\n", k));
			if (NULL == sdp->headfp) {
				sg_dev_arr[k] = NULL;
			}
		} else {	/* nothing active, simple case */
			SCSI_LOG_TIMEOUT(3, printk("sg_detach: dev=%d\n", k));
			sg_dev_arr[k] = NULL;
		}
		sg_nr_dev--;
		break;
	}
	write_unlock_irqrestore(&sg_dev_arr_lock, iflags);

	if (sdp) {
		sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
		class_simple_device_remove(MKDEV(SCSI_GENERIC_MAJOR, k));
		cdev_del(sdp->cdev);
		sdp->cdev = NULL;
		devfs_remove("%s/generic", scsidp->devfs_name);
		put_disk(sdp->disk);
		sdp->disk = NULL;
		if (NULL == sdp->headfp)
			kfree((char *) sdp);
	}

	if (delay)
		msleep(10);	/* dirty detach so delay device destruction */
}

/* Set 'perm' (4th argument) to 0 to disable module_param's definition
 * of sysfs parameters (which module_param doesn't yet support).
 * Sysfs parameters defined explicitly below.
 */
module_param_named(def_reserved_size, def_reserved_size, int, 0);
module_param_named(allow_dio, sg_allow_dio, int, 0);

MODULE_AUTHOR("Douglas Gilbert");
MODULE_DESCRIPTION("SCSI generic (sg) driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(SG_VERSION_STR);

MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");

static int __init
init_sg(void)
{
	int rc;

	if (def_reserved_size >= 0)
		sg_big_buff = def_reserved_size;

	rc = register_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), 
				    SG_MAX_DEVS, "sg");
	if (rc)
		return rc;
        sg_sysfs_class = class_simple_create(THIS_MODULE, "scsi_generic");
        if ( IS_ERR(sg_sysfs_class) ) {
		rc = PTR_ERR(sg_sysfs_class);
		goto err_out;
        }
	sg_sysfs_valid = 1;
	rc = scsi_register_interface(&sg_interface);
	if (0 == rc) {
#ifdef CONFIG_SCSI_PROC_FS
		sg_proc_init();
#endif				/* CONFIG_SCSI_PROC_FS */
		return 0;
	}
	class_simple_destroy(sg_sysfs_class);
err_out:
	unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), SG_MAX_DEVS);
	return rc;
}

static void __exit
exit_sg(void)
{
#ifdef CONFIG_SCSI_PROC_FS
	sg_proc_cleanup();
#endif				/* CONFIG_SCSI_PROC_FS */
	scsi_unregister_interface(&sg_interface);
	class_simple_destroy(sg_sysfs_class);
	sg_sysfs_valid = 0;
	unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0),
				 SG_MAX_DEVS);
	if (sg_dev_arr != NULL) {
		kfree((char *) sg_dev_arr);
		sg_dev_arr = NULL;
	}
	sg_dev_max = 0;
}

static int
sg_start_req(Sg_request * srp)
{
	int res;
	Sg_fd *sfp = srp->parentfp;
	sg_io_hdr_t *hp = &srp->header;
	int dxfer_len = (int) hp->dxfer_len;
	int dxfer_dir = hp->dxfer_direction;
	Sg_scatter_hold *req_schp = &srp->data;
	Sg_scatter_hold *rsv_schp = &sfp->reserve;

	SCSI_LOG_TIMEOUT(4, printk("sg_start_req: dxfer_len=%d\n", dxfer_len));
	if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
		return 0;
	if (sg_allow_dio && (hp->flags & SG_FLAG_DIRECT_IO) &&
	    (dxfer_dir != SG_DXFER_UNKNOWN) && (0 == hp->iovec_count) &&
	    (!sfp->parentdp->device->host->unchecked_isa_dma)) {
		res = sg_build_direct(srp, sfp, dxfer_len);
		if (res <= 0)	/* -ve -> error, 0 -> done, 1 -> try indirect */
			return res;
	}
	if ((!sg_res_in_use(sfp)) && (dxfer_len <= rsv_schp->bufflen))
		sg_link_reserve(sfp, srp, dxfer_len);
	else {
		res = sg_build_indirect(req_schp, sfp, dxfer_len);
		if (res) {
			sg_remove_scat(req_schp);
			return res;
		}
	}
	return 0;
}

static void
sg_finish_rem_req(Sg_request * srp)
{
	Sg_fd *sfp = srp->parentfp;
	Sg_scatter_hold *req_schp = &srp->data;

	SCSI_LOG_TIMEOUT(4, printk("sg_finish_rem_req: res_used=%d\n", (int) srp->res_used));
	if (srp->res_used)
		sg_unlink_reserve(sfp, srp);
	else
		sg_remove_scat(req_schp);
	sg_remove_request(sfp, srp);
}

static int
sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp, int tablesize)
{
	int ret_sz;
	int elem_sz = sizeof (struct scatterlist);
	int sg_bufflen = tablesize * elem_sz;
	int mx_sc_elems = tablesize;

	schp->buffer = sg_page_malloc(sg_bufflen, sfp->low_dma, &ret_sz);
	if (!schp->buffer)
		return -ENOMEM;
	else if (ret_sz != sg_bufflen) {
		sg_bufflen = ret_sz;
		mx_sc_elems = sg_bufflen / elem_sz;
	}
	schp->sglist_len = sg_bufflen;
	memset(schp->buffer, 0, sg_bufflen);
	return mx_sc_elems;	/* number of scat_gath elements allocated */
}

#ifdef SG_ALLOW_DIO_CODE
/* vvvvvvvv  following code borrowed from st driver's direct IO vvvvvvvvv */
	/* hopefully this generic code will moved to a library */

/* Pin down user pages and put them into a scatter gather list. Returns <= 0 if
   - mapping of all pages not successful
   - any page is above max_pfn
   (i.e., either completely successful or fails)
*/
static int 
st_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages, 
	          unsigned long uaddr, size_t count, int rw,
	          unsigned long max_pfn)
{
	int res, i, j;
	unsigned int nr_pages;
	struct page **pages;

	nr_pages = ((uaddr & ~PAGE_MASK) + count + ~PAGE_MASK) >> PAGE_SHIFT;

	/* User attempted Overflow! */
	if ((uaddr + count) < uaddr)
		return -EINVAL;

	/* Too big */
        if (nr_pages > max_pages)
		return -ENOMEM;

	/* Hmm? */
	if (count == 0)
		return 0;

	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_ATOMIC)) == NULL)
		return -ENOMEM;

        /* Try to fault in all of the necessary pages */
	down_read(&current->mm->mmap_sem);
        /* rw==READ means read from drive, write into memory area */
	res = get_user_pages(
		current,
		current->mm,
		uaddr,
		nr_pages,
		rw == READ,
		0, /* don't force */
		pages,
		NULL);
	up_read(&current->mm->mmap_sem);

	/* Errors and no page mapped should return here */
	if (res < nr_pages)
		goto out_unmap;

        for (i=0; i < nr_pages; i++) {
                /* FIXME: flush superflous for rw==READ,
                 * probably wrong function for rw==WRITE
                 */
		flush_dcache_page(pages[i]);
		if (page_to_pfn(pages[i]) > max_pfn)
			goto out_unlock;
		/* ?? Is locking needed? I don't think so */
		/* if (TestSetPageLocked(pages[i]))
		   goto out_unlock; */
        }

	/* Populate the scatter/gather list */
	sgl[0].page = pages[0]; 
	sgl[0].offset = uaddr & ~PAGE_MASK;
	if (nr_pages > 1) {
		sgl[0].length = PAGE_SIZE - sgl[0].offset;
		count -= sgl[0].length;
		for (i=1; i < nr_pages ; i++) {
			sgl[i].offset = 0;
			sgl[i].page = pages[i]; 
			sgl[i].length = count < PAGE_SIZE ? count : PAGE_SIZE;
			count -= PAGE_SIZE;
		}
	}
	else {
		sgl[0].length = count;
	}

	kfree(pages);
	return nr_pages;

 out_unlock:
	/* for (j=0; j < i; j++)
	   unlock_page(pages[j]); */
	res = 0;
 out_unmap:
	if (res > 0)
		for (j=0; j < res; j++)
			page_cache_release(pages[j]);
	kfree(pages);
	return res;
}


/* And unmap them... */
static int 
st_unmap_user_pages(struct scatterlist *sgl, const unsigned int nr_pages,
		    int dirtied)
{
	int i;

	for (i=0; i < nr_pages; i++) {
		if (dirtied && !PageReserved(sgl[i].page))
			SetPageDirty(sgl[i].page);
		/* unlock_page(sgl[i].page); */
		/* FIXME: cache flush missing for rw==READ
		 * FIXME: call the correct reference counting function
		 */
		page_cache_release(sgl[i].page);
	}

	return 0;
}

/* ^^^^^^^^  above code borrowed from st driver's direct IO ^^^^^^^^^ */
#endif


/* Returns: -ve -> error, 0 -> done, 1 -> try indirect */
static int
sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len)
{
#ifdef SG_ALLOW_DIO_CODE
	sg_io_hdr_t *hp = &srp->header;
	Sg_scatter_hold *schp = &srp->data;
	int sg_tablesize = sfp->parentdp->sg_tablesize;
	struct scatterlist *sgl;
	int mx_sc_elems, res;
	struct scsi_device *sdev = sfp->parentdp->device;

	if (((unsigned long)hp->dxferp &
			queue_dma_alignment(sdev->request_queue)) != 0)
		return 1;
	mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
        if (mx_sc_elems <= 0) {
                return 1;
        }
	sgl = (struct scatterlist *)schp->buffer;
	res = st_map_user_pages(sgl, mx_sc_elems, (unsigned long)hp->dxferp, dxfer_len, 
				(SG_DXFER_TO_DEV == hp->dxfer_direction) ? 1 : 0, ULONG_MAX);
	if (res <= 0)
		return 1;
	schp->k_use_sg = res;
	schp->dio_in_use = 1;
	hp->info |= SG_INFO_DIRECT_IO;
	return 0;
#else
	return 1;
#endif
}