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1// SPDX-License-Identifier: GPL-2.02/*3 * bsg.c - block layer implementation of the sg v4 interface4 */5#include <linux/module.h>6#include <linux/init.h>7#include <linux/file.h>8#include <linux/blkdev.h>9#include <linux/cdev.h>10#include <linux/jiffies.h>11#include <linux/percpu.h>12#include <linux/idr.h>13#include <linux/bsg.h>14#include <linux/slab.h>15 16#include <scsi/scsi.h>17#include <scsi/scsi_ioctl.h>18#include <scsi/sg.h>19 20#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"21#define BSG_VERSION "0.4"22 23struct bsg_device {24 struct request_queue *queue;25 struct device device;26 struct cdev cdev;27 int max_queue;28 unsigned int timeout;29 unsigned int reserved_size;30 bsg_sg_io_fn *sg_io_fn;31};32 33static inline struct bsg_device *to_bsg_device(struct inode *inode)34{35 return container_of(inode->i_cdev, struct bsg_device, cdev);36}37 38#define BSG_DEFAULT_CMDS 6439#define BSG_MAX_DEVS (1 << MINORBITS)40 41static DEFINE_IDA(bsg_minor_ida);42static const struct class bsg_class;43static int bsg_major;44 45static unsigned int bsg_timeout(struct bsg_device *bd, struct sg_io_v4 *hdr)46{47 unsigned int timeout = BLK_DEFAULT_SG_TIMEOUT;48 49 if (hdr->timeout)50 timeout = msecs_to_jiffies(hdr->timeout);51 else if (bd->timeout)52 timeout = bd->timeout;53 54 return max_t(unsigned int, timeout, BLK_MIN_SG_TIMEOUT);55}56 57static int bsg_sg_io(struct bsg_device *bd, bool open_for_write,58 void __user *uarg)59{60 struct sg_io_v4 hdr;61 int ret;62 63 if (copy_from_user(&hdr, uarg, sizeof(hdr)))64 return -EFAULT;65 if (hdr.guard != 'Q')66 return -EINVAL;67 ret = bd->sg_io_fn(bd->queue, &hdr, open_for_write,68 bsg_timeout(bd, &hdr));69 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr)))70 return -EFAULT;71 return ret;72}73 74static int bsg_open(struct inode *inode, struct file *file)75{76 if (!blk_get_queue(to_bsg_device(inode)->queue))77 return -ENXIO;78 return 0;79}80 81static int bsg_release(struct inode *inode, struct file *file)82{83 blk_put_queue(to_bsg_device(inode)->queue);84 return 0;85}86 87static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg)88{89 return put_user(READ_ONCE(bd->max_queue), uarg);90}91 92static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg)93{94 int max_queue;95 96 if (get_user(max_queue, uarg))97 return -EFAULT;98 if (max_queue < 1)99 return -EINVAL;100 WRITE_ONCE(bd->max_queue, max_queue);101 return 0;102}103 104static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)105{106 struct bsg_device *bd = to_bsg_device(file_inode(file));107 struct request_queue *q = bd->queue;108 void __user *uarg = (void __user *) arg;109 int __user *intp = uarg;110 int val;111 112 switch (cmd) {113 /*114 * Our own ioctls115 */116 case SG_GET_COMMAND_Q:117 return bsg_get_command_q(bd, uarg);118 case SG_SET_COMMAND_Q:119 return bsg_set_command_q(bd, uarg);120 121 /*122 * SCSI/sg ioctls123 */124 case SG_GET_VERSION_NUM:125 return put_user(30527, intp);126 case SCSI_IOCTL_GET_IDLUN:127 return put_user(0, intp);128 case SCSI_IOCTL_GET_BUS_NUMBER:129 return put_user(0, intp);130 case SG_SET_TIMEOUT:131 if (get_user(val, intp))132 return -EFAULT;133 bd->timeout = clock_t_to_jiffies(val);134 return 0;135 case SG_GET_TIMEOUT:136 return jiffies_to_clock_t(bd->timeout);137 case SG_GET_RESERVED_SIZE:138 return put_user(min(bd->reserved_size, queue_max_bytes(q)),139 intp);140 case SG_SET_RESERVED_SIZE:141 if (get_user(val, intp))142 return -EFAULT;143 if (val < 0)144 return -EINVAL;145 bd->reserved_size =146 min_t(unsigned int, val, queue_max_bytes(q));147 return 0;148 case SG_EMULATED_HOST:149 return put_user(1, intp);150 case SG_IO:151 return bsg_sg_io(bd, file->f_mode & FMODE_WRITE, uarg);152 case SCSI_IOCTL_SEND_COMMAND:153 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n",154 current->comm);155 return -EINVAL;156 default:157 return -ENOTTY;158 }159}160 161static const struct file_operations bsg_fops = {162 .open = bsg_open,163 .release = bsg_release,164 .unlocked_ioctl = bsg_ioctl,165 .compat_ioctl = compat_ptr_ioctl,166 .owner = THIS_MODULE,167 .llseek = default_llseek,168};169 170static void bsg_device_release(struct device *dev)171{172 struct bsg_device *bd = container_of(dev, struct bsg_device, device);173 174 ida_free(&bsg_minor_ida, MINOR(bd->device.devt));175 kfree(bd);176}177 178void bsg_unregister_queue(struct bsg_device *bd)179{180 struct gendisk *disk = bd->queue->disk;181 182 if (disk && disk->queue_kobj.sd)183 sysfs_remove_link(&disk->queue_kobj, "bsg");184 cdev_device_del(&bd->cdev, &bd->device);185 put_device(&bd->device);186}187EXPORT_SYMBOL_GPL(bsg_unregister_queue);188 189struct bsg_device *bsg_register_queue(struct request_queue *q,190 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn)191{192 struct bsg_device *bd;193 int ret;194 195 bd = kzalloc(sizeof(*bd), GFP_KERNEL);196 if (!bd)197 return ERR_PTR(-ENOMEM);198 bd->max_queue = BSG_DEFAULT_CMDS;199 bd->reserved_size = INT_MAX;200 bd->queue = q;201 bd->sg_io_fn = sg_io_fn;202 203 ret = ida_alloc_max(&bsg_minor_ida, BSG_MAX_DEVS - 1, GFP_KERNEL);204 if (ret < 0) {205 if (ret == -ENOSPC)206 dev_err(parent, "bsg: too many bsg devices\n");207 kfree(bd);208 return ERR_PTR(ret);209 }210 bd->device.devt = MKDEV(bsg_major, ret);211 bd->device.class = &bsg_class;212 bd->device.parent = parent;213 bd->device.release = bsg_device_release;214 dev_set_name(&bd->device, "%s", name);215 device_initialize(&bd->device);216 217 cdev_init(&bd->cdev, &bsg_fops);218 bd->cdev.owner = THIS_MODULE;219 ret = cdev_device_add(&bd->cdev, &bd->device);220 if (ret)221 goto out_put_device;222 223 if (q->disk && q->disk->queue_kobj.sd) {224 ret = sysfs_create_link(&q->disk->queue_kobj, &bd->device.kobj,225 "bsg");226 if (ret)227 goto out_device_del;228 }229 230 return bd;231 232out_device_del:233 cdev_device_del(&bd->cdev, &bd->device);234out_put_device:235 put_device(&bd->device);236 return ERR_PTR(ret);237}238EXPORT_SYMBOL_GPL(bsg_register_queue);239 240static char *bsg_devnode(const struct device *dev, umode_t *mode)241{242 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev));243}244 245static const struct class bsg_class = {246 .name = "bsg",247 .devnode = bsg_devnode,248};249 250static int __init bsg_init(void)251{252 dev_t devid;253 int ret;254 255 ret = class_register(&bsg_class);256 if (ret)257 return ret;258 259 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");260 if (ret)261 goto destroy_bsg_class;262 bsg_major = MAJOR(devid);263 264 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION265 " loaded (major %d)\n", bsg_major);266 return 0;267 268destroy_bsg_class:269 class_unregister(&bsg_class);270 return ret;271}272 273MODULE_AUTHOR("Jens Axboe");274MODULE_DESCRIPTION(BSG_DESCRIPTION);275MODULE_LICENSE("GPL");276 277device_initcall(bsg_init);278