drivers/block/aoe/aoechr.c

   1 /* Copyright (c) 2006 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         NMSG = 100,             /* message backlog to retain */
  19 };
  20
  21 struct aoe_chardev {
  22         ulong minor;
  23         char name[32];
  24 };
  25
  26 enum { EMFL_VALID = 1 };
  27
  28 struct ErrMsg {
  29         short flags;
  30         short len;
  31         char *msg;
  32 };
  33
  34 static struct ErrMsg emsgs[NMSG];
  35 static int emsgs_head_idx, emsgs_tail_idx;
  36 static struct semaphore emsgs_sema;
  37 static spinlock_t emsgs_lock;
  38 static int nblocked_emsgs_readers;
  39 static struct class *aoe_class;
  40 static struct aoe_chardev chardevs[] = {
  41         { MINOR_ERR, "err" },
  42         { MINOR_DISCOVER, "discover" },
  43         { MINOR_INTERFACES, "interfaces" },
  44         { MINOR_REVALIDATE, "revalidate" },
  45 };
  46
  47 static int
  48 discover(void)
  49 {
  50         aoecmd_cfg(0xffff, 0xff);
  51         return 0;
  52 }
  53
  54 static int
  55 interfaces(const char __user *str, size_t size)
  56 {
  57         if (set_aoe_iflist(str, size)) {
  58                 printk(KERN_ERR
  59                         "aoe: could not set interface list: too many interfaces\n");
  60                 return -EINVAL;
  61         }
  62         return 0;
  63 }
  64
  65 static int
  66 revalidate(const char __user *str, size_t size)
  67 {
  68         int major, minor, n;
  69         ulong flags;
  70         struct aoedev *d;
  71         char buf[16];
  72
  73         if (size >= sizeof buf)
  74                 return -EINVAL;
  75         buf[sizeof buf - 1] = '\0';
  76         if (copy_from_user(buf, str, size))
  77                 return -EFAULT;
  78
  79         /* should be e%d.%d format */
  80         n = sscanf(buf, "e%d.%d", &major, &minor);
  81         if (n != 2) {
  82                 printk(KERN_ERR "aoe: invalid device specification\n");
  83                 return -EINVAL;
  84         }
  85         d = aoedev_by_aoeaddr(major, minor);
  86         if (!d)
  87                 return -EINVAL;
  88
  89         spin_lock_irqsave(&d->lock, flags);
  90         d->flags &= ~DEVFL_MAXBCNT;
  91         d->flags |= DEVFL_PAUSE;
  92         spin_unlock_irqrestore(&d->lock, flags);
  93         aoecmd_cfg(major, minor);
  94
  95         return 0;
  96 }
  97
  98 void
  99 aoechr_error(char *msg)
 100 {
 101         struct ErrMsg *em;
 102         char *mp;
 103         ulong flags, n;
 104
 105         n = strlen(msg);
 106
 107         spin_lock_irqsave(&emsgs_lock, flags);
 108
 109         em = emsgs + emsgs_tail_idx;
 110         if ((em->flags & EMFL_VALID)) {
 111 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 112                 return;
 113         }
 114
 115         mp = kmalloc(n, GFP_ATOMIC);
 116         if (mp == NULL) {
 117                 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
 118                 goto bail;
 119         }
 120
 121         memcpy(mp, msg, n);
 122         em->msg = mp;
 123         em->flags |= EMFL_VALID;
 124         em->len = n;
 125
 126         emsgs_tail_idx++;
 127         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 128
 129         spin_unlock_irqrestore(&emsgs_lock, flags);
 130
 131         if (nblocked_emsgs_readers)
 132                 up(&emsgs_sema);
 133 }
 134
 135 static ssize_t
 136 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 137 {
 138         int ret = -EINVAL;
 139
 140         switch ((unsigned long) filp->private_data) {
 141         default:
 142                 printk(KERN_INFO "aoe: can't write to that file.\n");
 143                 break;
 144         case MINOR_DISCOVER:
 145                 ret = discover();
 146                 break;
 147         case MINOR_INTERFACES:
 148                 ret = interfaces(buf, cnt);
 149                 break;
 150         case MINOR_REVALIDATE:
 151                 ret = revalidate(buf, cnt);
 152         }
 153         if (ret == 0)
 154                 ret = cnt;
 155         return ret;
 156 }
 157
 158 static int
 159 aoechr_open(struct inode *inode, struct file *filp)
 160 {
 161         int n, i;
 162
 163         n = iminor(inode);
 164         filp->private_data = (void *) (unsigned long) n;
 165
 166         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 167                 if (chardevs[i].minor == n)
 168                         return 0;
 169         return -EINVAL;
 170 }
 171
 172 static int
 173 aoechr_rel(struct inode *inode, struct file *filp)
 174 {
 175         return 0;
 176 }
 177
 178 static ssize_t
 179 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 180 {
 181         unsigned long n;
 182         char *mp;
 183         struct ErrMsg *em;
 184         ssize_t len;
 185         ulong flags;
 186
 187         n = (unsigned long) filp->private_data;
 188         switch (n) {
 189         case MINOR_ERR:
 190                 spin_lock_irqsave(&emsgs_lock, flags);
 191 loop:
 192                 em = emsgs + emsgs_head_idx;
 193                 if ((em->flags & EMFL_VALID) == 0) {
 194                         if (filp->f_flags & O_NDELAY) {
 195                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 196                                 return -EAGAIN;
 197                         }
 198                         nblocked_emsgs_readers++;
 199
 200                         spin_unlock_irqrestore(&emsgs_lock, flags);
 201
 202                         n = down_interruptible(&emsgs_sema);
 203
 204                         spin_lock_irqsave(&emsgs_lock, flags);
 205
 206                         nblocked_emsgs_readers--;
 207
 208                         if (n) {
 209                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 210                                 return -ERESTARTSYS;
 211                         }
 212                         goto loop;
 213                 }
 214                 if (em->len > cnt) {
 215                         spin_unlock_irqrestore(&emsgs_lock, flags);
 216                         return -EAGAIN;
 217                 }
 218                 mp = em->msg;
 219                 len = em->len;
 220                 em->msg = NULL;
 221                 em->flags &= ~EMFL_VALID;
 222
 223                 emsgs_head_idx++;
 224                 emsgs_head_idx %= ARRAY_SIZE(emsgs);
 225
 226                 spin_unlock_irqrestore(&emsgs_lock, flags);
 227
 228                 n = copy_to_user(buf, mp, len);
 229                 kfree(mp);
 230                 return n == 0 ? len : -EFAULT;
 231         default:
 232                 return -EFAULT;
 233         }
 234 }
 235
 236 static struct file_operations aoe_fops = {
 237         .write = aoechr_write,
 238         .read = aoechr_read,
 239         .open = aoechr_open,
 240         .release = aoechr_rel,
 241         .owner = THIS_MODULE,
 242 };
 243
 244 int __init
 245 aoechr_init(void)
 246 {
 247         int n, i;
 248
 249         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 250         if (n < 0) {
 251                 printk(KERN_ERR "aoe: can't register char device\n");
 252                 return n;
 253         }
 254         sema_init(&emsgs_sema, 0);
 255         spin_lock_init(&emsgs_lock);
 256         aoe_class = class_create(THIS_MODULE, "aoe");
 257         if (IS_ERR(aoe_class)) {
 258                 unregister_chrdev(AOE_MAJOR, "aoechr");
 259                 return PTR_ERR(aoe_class);
 260         }
 261         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 262                 class_device_create(aoe_class, NULL,
 263                                         MKDEV(AOE_MAJOR, chardevs[i].minor),
 264                                         NULL, chardevs[i].name);
 265
 266         return 0;
 267 }
 268
 269 void
 270 aoechr_exit(void)
 271 {
 272         int i;
 273
 274         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 275                 class_device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 276         class_destroy(aoe_class);
 277         unregister_chrdev(AOE_MAJOR, "aoechr");
 278 }
 279