drivers/block/aoe/aoechr.c

   1 /* Copyright (c) 2007 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 <linux/delay.h>
  10 #include "aoe.h"
  11
  12 enum {
  13         //MINOR_STAT = 1, (moved to sysfs)
  14         MINOR_ERR = 2,
  15         MINOR_DISCOVER,
  16         MINOR_INTERFACES,
  17         MINOR_REVALIDATE,
  18         MINOR_FLUSH,
  19         MSGSZ = 2048,
  20         NMSG = 100,             /* message backlog to retain */
  21 };
  22
  23 struct aoe_chardev {
  24         ulong minor;
  25         char name[32];
  26 };
  27
  28 enum { EMFL_VALID = 1 };
  29
  30 struct ErrMsg {
  31         short flags;
  32         short len;
  33         char *msg;
  34 };
  35
  36 static struct ErrMsg emsgs[NMSG];
  37 static int emsgs_head_idx, emsgs_tail_idx;
  38 static struct semaphore emsgs_sema;
  39 static spinlock_t emsgs_lock;
  40 static int nblocked_emsgs_readers;
  41 static struct class *aoe_class;
  42 static struct aoe_chardev chardevs[] = {
  43         { MINOR_ERR, "err" },
  44         { MINOR_DISCOVER, "discover" },
  45         { MINOR_INTERFACES, "interfaces" },
  46         { MINOR_REVALIDATE, "revalidate" },
  47         { MINOR_FLUSH, "flush" },
  48 };
  49
  50 static int
  51 discover(void)
  52 {
  53         aoecmd_cfg(0xffff, 0xff);
  54         return 0;
  55 }
  56
  57 static int
  58 interfaces(const char __user *str, size_t size)
  59 {
  60         if (set_aoe_iflist(str, size)) {
  61                 printk(KERN_ERR
  62                         "aoe: could not set interface list: too many interfaces\n");
  63                 return -EINVAL;
  64         }
  65         return 0;
  66 }
  67
  68 static int
  69 revalidate(const char __user *str, size_t size)
  70 {
  71         int major, minor, n;
  72         ulong flags;
  73         struct aoedev *d;
  74         struct sk_buff *skb;
  75         char buf[16];
  76
  77         if (size >= sizeof buf)
  78                 return -EINVAL;
  79         buf[sizeof buf - 1] = '\0';
  80         if (copy_from_user(buf, str, size))
  81                 return -EFAULT;
  82
  83         /* should be e%d.%d format */
  84         n = sscanf(buf, "e%d.%d", &major, &minor);
  85         if (n != 2) {
  86                 printk(KERN_ERR "aoe: invalid device specification\n");
  87                 return -EINVAL;
  88         }
  89         d = aoedev_by_aoeaddr(major, minor);
  90         if (!d)
  91                 return -EINVAL;
  92         spin_lock_irqsave(&d->lock, flags);
  93         aoecmd_cleanslate(d);
  94 loop:
  95         skb = aoecmd_ata_id(d);
  96         spin_unlock_irqrestore(&d->lock, flags);
  97         /* try again if we are able to sleep a bit,
  98          * otherwise give up this revalidation
  99          */
 100         if (!skb && !msleep_interruptible(200)) {
 101                 spin_lock_irqsave(&d->lock, flags);
 102                 goto loop;
 103         }
 104         aoenet_xmit(skb);
 105         aoecmd_cfg(major, minor);
 106         return 0;
 107 }
 108
 109 void
 110 aoechr_error(char *msg)
 111 {
 112         struct ErrMsg *em;
 113         char *mp;
 114         ulong flags, n;
 115
 116         n = strlen(msg);
 117
 118         spin_lock_irqsave(&emsgs_lock, flags);
 119
 120         em = emsgs + emsgs_tail_idx;
 121         if ((em->flags & EMFL_VALID)) {
 122 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 123                 return;
 124         }
 125
 126         mp = kmalloc(n, GFP_ATOMIC);
 127         if (mp == NULL) {
 128                 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
 129                 goto bail;
 130         }
 131
 132         memcpy(mp, msg, n);
 133         em->msg = mp;
 134         em->flags |= EMFL_VALID;
 135         em->len = n;
 136
 137         emsgs_tail_idx++;
 138         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 139
 140         spin_unlock_irqrestore(&emsgs_lock, flags);
 141
 142         if (nblocked_emsgs_readers)
 143                 up(&emsgs_sema);
 144 }
 145
 146 static ssize_t
 147 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 148 {
 149         int ret = -EINVAL;
 150
 151         switch ((unsigned long) filp->private_data) {
 152         default:
 153                 printk(KERN_INFO "aoe: can't write to that file.\n");
 154                 break;
 155         case MINOR_DISCOVER:
 156                 ret = discover();
 157                 break;
 158         case MINOR_INTERFACES:
 159                 ret = interfaces(buf, cnt);
 160                 break;
 161         case MINOR_REVALIDATE:
 162                 ret = revalidate(buf, cnt);
 163                 break;
 164         case MINOR_FLUSH:
 165                 ret = aoedev_flush(buf, cnt);
 166         }
 167         if (ret == 0)
 168                 ret = cnt;
 169         return ret;
 170 }
 171
 172 static int
 173 aoechr_open(struct inode *inode, struct file *filp)
 174 {
 175         int n, i;
 176
 177         n = iminor(inode);
 178         filp->private_data = (void *) (unsigned long) n;
 179
 180         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 181                 if (chardevs[i].minor == n)
 182                         return 0;
 183         return -EINVAL;
 184 }
 185
 186 static int
 187 aoechr_rel(struct inode *inode, struct file *filp)
 188 {
 189         return 0;
 190 }
 191
 192 static ssize_t
 193 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 194 {
 195         unsigned long n;
 196         char *mp;
 197         struct ErrMsg *em;
 198         ssize_t len;
 199         ulong flags;
 200
 201         n = (unsigned long) filp->private_data;
 202         if (n != MINOR_ERR)
 203                 return -EFAULT;
 204
 205         spin_lock_irqsave(&emsgs_lock, flags);
 206
 207         for (;;) {
 208                 em = emsgs + emsgs_head_idx;
 209                 if ((em->flags & EMFL_VALID) != 0)
 210                         break;
 211                 if (filp->f_flags & O_NDELAY) {
 212                         spin_unlock_irqrestore(&emsgs_lock, flags);
 213                         return -EAGAIN;
 214                 }
 215                 nblocked_emsgs_readers++;
 216
 217                 spin_unlock_irqrestore(&emsgs_lock, flags);
 218
 219                 n = down_interruptible(&emsgs_sema);
 220
 221                 spin_lock_irqsave(&emsgs_lock, flags);
 222
 223                 nblocked_emsgs_readers--;
 224
 225                 if (n) {
 226                         spin_unlock_irqrestore(&emsgs_lock, flags);
 227                         return -ERESTARTSYS;
 228                 }
 229         }
 230         if (em->len > cnt) {
 231                 spin_unlock_irqrestore(&emsgs_lock, flags);
 232                 return -EAGAIN;
 233         }
 234         mp = em->msg;
 235         len = em->len;
 236         em->msg = NULL;
 237         em->flags &= ~EMFL_VALID;
 238
 239         emsgs_head_idx++;
 240         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 241
 242         spin_unlock_irqrestore(&emsgs_lock, flags);
 243
 244         n = copy_to_user(buf, mp, len);
 245         kfree(mp);
 246         return n == 0 ? len : -EFAULT;
 247 }
 248
 249 static const struct file_operations aoe_fops = {
 250         .write = aoechr_write,
 251         .read = aoechr_read,
 252         .open = aoechr_open,
 253         .release = aoechr_rel,
 254         .owner = THIS_MODULE,
 255 };
 256
 257 int __init
 258 aoechr_init(void)
 259 {
 260         int n, i;
 261
 262         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 263         if (n < 0) {
 264                 printk(KERN_ERR "aoe: can't register char device\n");
 265                 return n;
 266         }
 267         sema_init(&emsgs_sema, 0);
 268         spin_lock_init(&emsgs_lock);
 269         aoe_class = class_create(THIS_MODULE, "aoe");
 270         if (IS_ERR(aoe_class)) {
 271                 unregister_chrdev(AOE_MAJOR, "aoechr");
 272                 return PTR_ERR(aoe_class);
 273         }
 274         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 275                 device_create(aoe_class, NULL,
 276                               MKDEV(AOE_MAJOR, chardevs[i].minor), chardevs[i].name);
 277
 278         return 0;
 279 }
 280
 281 void
 282 aoechr_exit(void)
 283 {
 284         int i;
 285
 286         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 287                 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 288         class_destroy(aoe_class);
 289         unregister_chrdev(AOE_MAJOR, "aoechr");
 290 }
 291