bsg.c (6264B)
1// SPDX-License-Identifier: GPL-2.0 2/* 3 * bsg.c - block layer implementation of the sg v4 interface 4 */ 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 64 39#define BSG_MAX_DEVS 32768 40 41static DEFINE_IDA(bsg_minor_ida); 42static 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, fmode_t mode, void __user *uarg) 58{ 59 struct sg_io_v4 hdr; 60 int ret; 61 62 if (copy_from_user(&hdr, uarg, sizeof(hdr))) 63 return -EFAULT; 64 if (hdr.guard != 'Q') 65 return -EINVAL; 66 ret = bd->sg_io_fn(bd->queue, &hdr, mode, bsg_timeout(bd, &hdr)); 67 if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr))) 68 return -EFAULT; 69 return ret; 70} 71 72static int bsg_open(struct inode *inode, struct file *file) 73{ 74 if (!blk_get_queue(to_bsg_device(inode)->queue)) 75 return -ENXIO; 76 return 0; 77} 78 79static int bsg_release(struct inode *inode, struct file *file) 80{ 81 blk_put_queue(to_bsg_device(inode)->queue); 82 return 0; 83} 84 85static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg) 86{ 87 return put_user(READ_ONCE(bd->max_queue), uarg); 88} 89 90static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg) 91{ 92 int max_queue; 93 94 if (get_user(max_queue, uarg)) 95 return -EFAULT; 96 if (max_queue < 1) 97 return -EINVAL; 98 WRITE_ONCE(bd->max_queue, max_queue); 99 return 0; 100} 101 102static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 103{ 104 struct bsg_device *bd = to_bsg_device(file_inode(file)); 105 struct request_queue *q = bd->queue; 106 void __user *uarg = (void __user *) arg; 107 int __user *intp = uarg; 108 int val; 109 110 switch (cmd) { 111 /* 112 * Our own ioctls 113 */ 114 case SG_GET_COMMAND_Q: 115 return bsg_get_command_q(bd, uarg); 116 case SG_SET_COMMAND_Q: 117 return bsg_set_command_q(bd, uarg); 118 119 /* 120 * SCSI/sg ioctls 121 */ 122 case SG_GET_VERSION_NUM: 123 return put_user(30527, intp); 124 case SCSI_IOCTL_GET_IDLUN: 125 return put_user(0, intp); 126 case SCSI_IOCTL_GET_BUS_NUMBER: 127 return put_user(0, intp); 128 case SG_SET_TIMEOUT: 129 if (get_user(val, intp)) 130 return -EFAULT; 131 bd->timeout = clock_t_to_jiffies(val); 132 return 0; 133 case SG_GET_TIMEOUT: 134 return jiffies_to_clock_t(bd->timeout); 135 case SG_GET_RESERVED_SIZE: 136 return put_user(min(bd->reserved_size, queue_max_bytes(q)), 137 intp); 138 case SG_SET_RESERVED_SIZE: 139 if (get_user(val, intp)) 140 return -EFAULT; 141 if (val < 0) 142 return -EINVAL; 143 bd->reserved_size = 144 min_t(unsigned int, val, queue_max_bytes(q)); 145 return 0; 146 case SG_EMULATED_HOST: 147 return put_user(1, intp); 148 case SG_IO: 149 return bsg_sg_io(bd, file->f_mode, uarg); 150 case SCSI_IOCTL_SEND_COMMAND: 151 pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n", 152 current->comm); 153 return -EINVAL; 154 default: 155 return -ENOTTY; 156 } 157} 158 159static const struct file_operations bsg_fops = { 160 .open = bsg_open, 161 .release = bsg_release, 162 .unlocked_ioctl = bsg_ioctl, 163 .compat_ioctl = compat_ptr_ioctl, 164 .owner = THIS_MODULE, 165 .llseek = default_llseek, 166}; 167 168static void bsg_device_release(struct device *dev) 169{ 170 struct bsg_device *bd = container_of(dev, struct bsg_device, device); 171 172 ida_simple_remove(&bsg_minor_ida, MINOR(bd->device.devt)); 173 kfree(bd); 174} 175 176void bsg_unregister_queue(struct bsg_device *bd) 177{ 178 if (bd->queue->kobj.sd) 179 sysfs_remove_link(&bd->queue->kobj, "bsg"); 180 cdev_device_del(&bd->cdev, &bd->device); 181 put_device(&bd->device); 182} 183EXPORT_SYMBOL_GPL(bsg_unregister_queue); 184 185struct bsg_device *bsg_register_queue(struct request_queue *q, 186 struct device *parent, const char *name, bsg_sg_io_fn *sg_io_fn) 187{ 188 struct bsg_device *bd; 189 int ret; 190 191 bd = kzalloc(sizeof(*bd), GFP_KERNEL); 192 if (!bd) 193 return ERR_PTR(-ENOMEM); 194 bd->max_queue = BSG_DEFAULT_CMDS; 195 bd->reserved_size = INT_MAX; 196 bd->queue = q; 197 bd->sg_io_fn = sg_io_fn; 198 199 ret = ida_simple_get(&bsg_minor_ida, 0, BSG_MAX_DEVS, GFP_KERNEL); 200 if (ret < 0) { 201 if (ret == -ENOSPC) 202 dev_err(parent, "bsg: too many bsg devices\n"); 203 kfree(bd); 204 return ERR_PTR(ret); 205 } 206 bd->device.devt = MKDEV(bsg_major, ret); 207 bd->device.class = bsg_class; 208 bd->device.parent = parent; 209 bd->device.release = bsg_device_release; 210 dev_set_name(&bd->device, "%s", name); 211 device_initialize(&bd->device); 212 213 cdev_init(&bd->cdev, &bsg_fops); 214 bd->cdev.owner = THIS_MODULE; 215 ret = cdev_device_add(&bd->cdev, &bd->device); 216 if (ret) 217 goto out_put_device; 218 219 if (q->kobj.sd) { 220 ret = sysfs_create_link(&q->kobj, &bd->device.kobj, "bsg"); 221 if (ret) 222 goto out_device_del; 223 } 224 225 return bd; 226 227out_device_del: 228 cdev_device_del(&bd->cdev, &bd->device); 229out_put_device: 230 put_device(&bd->device); 231 return ERR_PTR(ret); 232} 233EXPORT_SYMBOL_GPL(bsg_register_queue); 234 235static char *bsg_devnode(struct device *dev, umode_t *mode) 236{ 237 return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev)); 238} 239 240static int __init bsg_init(void) 241{ 242 dev_t devid; 243 int ret; 244 245 bsg_class = class_create(THIS_MODULE, "bsg"); 246 if (IS_ERR(bsg_class)) 247 return PTR_ERR(bsg_class); 248 bsg_class->devnode = bsg_devnode; 249 250 ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg"); 251 if (ret) 252 goto destroy_bsg_class; 253 bsg_major = MAJOR(devid); 254 255 printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION 256 " loaded (major %d)\n", bsg_major); 257 return 0; 258 259destroy_bsg_class: 260 class_destroy(bsg_class); 261 return ret; 262} 263 264MODULE_AUTHOR("Jens Axboe"); 265MODULE_DESCRIPTION(BSG_DESCRIPTION); 266MODULE_LICENSE("GPL"); 267 268device_initcall(bsg_init);