drivers/block/aoe/aoechr.c

   1 /* Copyright (c) 2004 Coraid, Inc.  See COPYING for GPL terms. */
   2 /*
   3  * aoechr.c
   4  * AoE character device driver
   5  */
   6
   7 #include <linux/hdreg.h>
   8 #include <linux/blkdev.h>
   9 #include "aoe.h"
  10
  11 enum {
  12         //MINOR_STAT = 1, (moved to sysfs)
  13         MINOR_ERR = 2,
  14         MINOR_DISCOVER,
  15         MINOR_INTERFACES,
  16         MINOR_REVALIDATE,
  17         MSGSZ = 2048,
  18         NARGS = 10,
  19         NMSG = 100,             /* message backlog to retain */
  20 };
  21
  22 struct aoe_chardev {
  23         ulong minor;
  24         char name[32];
  25 };
  26
  27 enum { EMFL_VALID = 1 };
  28
  29 struct ErrMsg {
  30         short flags;
  31         short len;
  32         char *msg;
  33 };
  34
  35 static struct ErrMsg emsgs[NMSG];
  36 static int emsgs_head_idx, emsgs_tail_idx;
  37 static struct semaphore emsgs_sema;
  38 static spinlock_t emsgs_lock;
  39 static int nblocked_emsgs_readers;
  40 static struct class *aoe_class;
  41 static struct aoe_chardev chardevs[] = {
  42         { MINOR_ERR, "err" },
  43         { MINOR_DISCOVER, "discover" },
  44         { MINOR_INTERFACES, "interfaces" },
  45         { MINOR_REVALIDATE, "revalidate" },
  46 };
  47
  48 static int
  49 discover(void)
  50 {
  51         aoecmd_cfg(0xffff, 0xff);
  52         return 0;
  53 }
  54
  55 static int
  56 interfaces(const char __user *str, size_t size)
  57 {
  58         if (set_aoe_iflist(str, size)) {
  59                 printk(KERN_CRIT
  60                        "%s: could not set interface list: %s\n",
  61                        __FUNCTION__, "too many interfaces");
  62                 return -EINVAL;
  63         }
  64         return 0;
  65 }
  66
  67 static int
  68 revalidate(const char __user *str, size_t size)
  69 {
  70         int major, minor, n;
  71         ulong flags;
  72         struct aoedev *d;
  73         char buf[16];
  74
  75         if (size >= sizeof buf)
  76                 return -EINVAL;
  77         buf[sizeof buf - 1] = '\0';
  78         if (copy_from_user(buf, str, size))
  79                 return -EFAULT;
  80
  81         /* should be e%d.%d format */
  82         n = sscanf(buf, "e%d.%d", &major, &minor);
  83         if (n != 2) {
  84                 printk(KERN_ERR "aoe: %s: invalid device specification\n",
  85                         __FUNCTION__);
  86                 return -EINVAL;
  87         }
  88         d = aoedev_by_aoeaddr(major, minor);
  89         if (!d)
  90                 return -EINVAL;
  91
  92         spin_lock_irqsave(&d->lock, flags);
  93         d->flags |= DEVFL_PAUSE;
  94         spin_unlock_irqrestore(&d->lock, flags);
  95         aoecmd_cfg(major, minor);
  96
  97         return 0;
  98 }
  99
 100 void
 101 aoechr_error(char *msg)
 102 {
 103         struct ErrMsg *em;
 104         char *mp;
 105         ulong flags, n;
 106
 107         n = strlen(msg);
 108
 109         spin_lock_irqsave(&emsgs_lock, flags);
 110
 111         em = emsgs + emsgs_tail_idx;
 112         if ((em->flags & EMFL_VALID)) {
 113 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 114                 return;
 115         }
 116
 117         mp = kmalloc(n, GFP_ATOMIC);
 118         if (mp == NULL) {
 119                 printk(KERN_CRIT "aoe: aoechr_error: allocation failure, len=%ld\n", n);
 120                 goto bail;
 121         }
 122
 123         memcpy(mp, msg, n);
 124         em->msg = mp;
 125         em->flags |= EMFL_VALID;
 126         em->len = n;
 127
 128         emsgs_tail_idx++;
 129         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 130
 131         spin_unlock_irqrestore(&emsgs_lock, flags);
 132
 133         if (nblocked_emsgs_readers)
 134                 up(&emsgs_sema);
 135 }
 136
 137 static ssize_t
 138 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 139 {
 140         int ret = -EINVAL;
 141
 142         switch ((unsigned long) filp->private_data) {
 143         default:
 144                 printk(KERN_INFO "aoe: aoechr_write: can't write to that file.\n");
 145                 break;
 146         case MINOR_DISCOVER:
 147                 ret = discover();
 148                 break;
 149         case MINOR_INTERFACES:
 150                 ret = interfaces(buf, cnt);
 151                 break;
 152         case MINOR_REVALIDATE:
 153                 ret = revalidate(buf, cnt);
 154         }
 155         if (ret == 0)
 156                 ret = cnt;
 157         return ret;
 158 }
 159
 160 static int
 161 aoechr_open(struct inode *inode, struct file *filp)
 162 {
 163         int n, i;
 164
 165         n = MINOR(inode->i_rdev);
 166         filp->private_data = (void *) (unsigned long) n;
 167
 168         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 169                 if (chardevs[i].minor == n)
 170                         return 0;
 171         return -EINVAL;
 172 }
 173
 174 static int
 175 aoechr_rel(struct inode *inode, struct file *filp)
 176 {
 177         return 0;
 178 }
 179
 180 static ssize_t
 181 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 182 {
 183         unsigned long n;
 184         char *mp;
 185         struct ErrMsg *em;
 186         ssize_t len;
 187         ulong flags;
 188
 189         n = (unsigned long) filp->private_data;
 190         switch (n) {
 191         case MINOR_ERR:
 192                 spin_lock_irqsave(&emsgs_lock, flags);
 193 loop:
 194                 em = emsgs + emsgs_head_idx;
 195                 if ((em->flags & EMFL_VALID) == 0) {
 196                         if (filp->f_flags & O_NDELAY) {
 197                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 198                                 return -EAGAIN;
 199                         }
 200                         nblocked_emsgs_readers++;
 201
 202                         spin_unlock_irqrestore(&emsgs_lock, flags);
 203
 204                         n = down_interruptible(&emsgs_sema);
 205
 206                         spin_lock_irqsave(&emsgs_lock, flags);
 207
 208                         nblocked_emsgs_readers--;
 209
 210                         if (n) {
 211                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 212                                 return -ERESTARTSYS;
 213                         }
 214                         goto loop;
 215                 }
 216                 if (em->len > cnt) {
 217                         spin_unlock_irqrestore(&emsgs_lock, flags);
 218                         return -EAGAIN;
 219                 }
 220                 mp = em->msg;
 221                 len = em->len;
 222                 em->msg = NULL;
 223                 em->flags &= ~EMFL_VALID;
 224
 225                 emsgs_head_idx++;
 226                 emsgs_head_idx %= ARRAY_SIZE(emsgs);
 227
 228                 spin_unlock_irqrestore(&emsgs_lock, flags);
 229
 230                 n = copy_to_user(buf, mp, len);
 231                 kfree(mp);
 232                 return n == 0 ? len : -EFAULT;
 233         default:
 234                 return -EFAULT;
 235         }
 236 }
 237
 238 static struct file_operations aoe_fops = {
 239         .write = aoechr_write,
 240         .read = aoechr_read,
 241         .open = aoechr_open,
 242         .release = aoechr_rel,
 243         .owner = THIS_MODULE,
 244 };
 245
 246 int __init
 247 aoechr_init(void)
 248 {
 249         int n, i;
 250
 251         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 252         if (n < 0) {
 253                 printk(KERN_ERR "aoe: aoechr_init: can't register char device\n");
 254                 return n;
 255         }
 256         sema_init(&emsgs_sema, 0);
 257         spin_lock_init(&emsgs_lock);
 258         aoe_class = class_create(THIS_MODULE, "aoe");
 259         if (IS_ERR(aoe_class)) {
 260                 unregister_chrdev(AOE_MAJOR, "aoechr");
 261                 return PTR_ERR(aoe_class);
 262         }
 263         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 264                 class_device_create(aoe_class, NULL,
 265                                         MKDEV(AOE_MAJOR, chardevs[i].minor),
 266                                         NULL, chardevs[i].name);
 267
 268         return 0;
 269 }
 270
 271 void
 272 aoechr_exit(void)
 273 {
 274         int i;
 275
 276         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 277                 class_device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 278         class_destroy(aoe_class);
 279         unregister_chrdev(AOE_MAJOR, "aoechr");
 280 }
 281