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/completion.h>
  10 #include <linux/delay.h>
  11 #include <linux/slab.h>
  12 #include <linux/mutex.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/export.h>
  15 #include "aoe.h"
  16
  17 enum {
  18         //MINOR_STAT = 1, (moved to sysfs)
  19         MINOR_ERR = 2,
  20         MINOR_DISCOVER,
  21         MINOR_INTERFACES,
  22         MINOR_REVALIDATE,
  23         MINOR_FLUSH,
  24         MSGSZ = 2048,
  25         NMSG = 100,             /* message backlog to retain */
  26 };
  27
  28 struct aoe_chardev {
  29         ulong minor;
  30         char name[32];
  31 };
  32
  33 enum { EMFL_VALID = 1 };
  34
  35 struct ErrMsg {
  36         short flags;
  37         short len;
  38         char *msg;
  39 };
  40
  41 static DEFINE_MUTEX(aoechr_mutex);
  42 static struct ErrMsg emsgs[NMSG];
  43 static int emsgs_head_idx, emsgs_tail_idx;
  44 static struct completion emsgs_comp;
  45 static spinlock_t emsgs_lock;
  46 static int nblocked_emsgs_readers;
  47 static struct class *aoe_class;
  48 static struct aoe_chardev chardevs[] = {
  49         { MINOR_ERR, "err" },
  50         { MINOR_DISCOVER, "discover" },
  51         { MINOR_INTERFACES, "interfaces" },
  52         { MINOR_REVALIDATE, "revalidate" },
  53         { MINOR_FLUSH, "flush" },
  54 };
  55
  56 static int
  57 discover(void)
  58 {
  59         aoecmd_cfg(0xffff, 0xff);
  60         return 0;
  61 }
  62
  63 static int
  64 interfaces(const char __user *str, size_t size)
  65 {
  66         if (set_aoe_iflist(str, size)) {
  67                 printk(KERN_ERR
  68                         "aoe: could not set interface list: too many interfaces\n");
  69                 return -EINVAL;
  70         }
  71         return 0;
  72 }
  73
  74 static int
  75 revalidate(const char __user *str, size_t size)
  76 {
  77         int major, minor, n;
  78         ulong flags;
  79         struct aoedev *d;
  80         struct sk_buff *skb;
  81         char buf[16];
  82
  83         if (size >= sizeof buf)
  84                 return -EINVAL;
  85         buf[sizeof buf - 1] = '\0';
  86         if (copy_from_user(buf, str, size))
  87                 return -EFAULT;
  88
  89         n = sscanf(buf, "e%d.%d", &major, &minor);
  90         if (n != 2) {
  91                 pr_err("aoe: invalid device specification %s\n", buf);
  92                 return -EINVAL;
  93         }
  94         d = aoedev_by_aoeaddr(major, minor);
  95         if (!d)
  96                 return -EINVAL;
  97         spin_lock_irqsave(&d->lock, flags);
  98         aoecmd_cleanslate(d);
  99 loop:
 100         skb = aoecmd_ata_id(d);
 101         spin_unlock_irqrestore(&d->lock, flags);
 102         /* try again if we are able to sleep a bit,
 103          * otherwise give up this revalidation
 104          */
 105         if (!skb && !msleep_interruptible(200)) {
 106                 spin_lock_irqsave(&d->lock, flags);
 107                 goto loop;
 108         }
 109         aoedev_put(d);
 110         if (skb) {
 111                 struct sk_buff_head queue;
 112                 __skb_queue_head_init(&queue);
 113                 __skb_queue_tail(&queue, skb);
 114                 aoenet_xmit(&queue);
 115         }
 116         aoecmd_cfg(major, minor);
 117         return 0;
 118 }
 119
 120 void
 121 aoechr_error(char *msg)
 122 {
 123         struct ErrMsg *em;
 124         char *mp;
 125         ulong flags, n;
 126
 127         n = strlen(msg);
 128
 129         spin_lock_irqsave(&emsgs_lock, flags);
 130
 131         em = emsgs + emsgs_tail_idx;
 132         if ((em->flags & EMFL_VALID)) {
 133 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 134                 return;
 135         }
 136
 137         mp = kmalloc(n, GFP_ATOMIC);
 138         if (mp == NULL) {
 139                 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
 140                 goto bail;
 141         }
 142
 143         memcpy(mp, msg, n);
 144         em->msg = mp;
 145         em->flags |= EMFL_VALID;
 146         em->len = n;
 147
 148         emsgs_tail_idx++;
 149         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 150
 151         spin_unlock_irqrestore(&emsgs_lock, flags);
 152
 153         if (nblocked_emsgs_readers)
 154                 complete(&emsgs_comp);
 155 }
 156
 157 static ssize_t
 158 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 159 {
 160         int ret = -EINVAL;
 161
 162         switch ((unsigned long) filp->private_data) {
 163         default:
 164                 printk(KERN_INFO "aoe: can't write to that file.\n");
 165                 break;
 166         case MINOR_DISCOVER:
 167                 ret = discover();
 168                 break;
 169         case MINOR_INTERFACES:
 170                 ret = interfaces(buf, cnt);
 171                 break;
 172         case MINOR_REVALIDATE:
 173                 ret = revalidate(buf, cnt);
 174                 break;
 175         case MINOR_FLUSH:
 176                 ret = aoedev_flush(buf, cnt);
 177         }
 178         if (ret == 0)
 179                 ret = cnt;
 180         return ret;
 181 }
 182
 183 static int
 184 aoechr_open(struct inode *inode, struct file *filp)
 185 {
 186         int n, i;
 187
 188         mutex_lock(&aoechr_mutex);
 189         n = iminor(inode);
 190         filp->private_data = (void *) (unsigned long) n;
 191
 192         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 193                 if (chardevs[i].minor == n) {
 194                         mutex_unlock(&aoechr_mutex);
 195                         return 0;
 196                 }
 197         mutex_unlock(&aoechr_mutex);
 198         return -EINVAL;
 199 }
 200
 201 static int
 202 aoechr_rel(struct inode *inode, struct file *filp)
 203 {
 204         return 0;
 205 }
 206
 207 static ssize_t
 208 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 209 {
 210         unsigned long n;
 211         char *mp;
 212         struct ErrMsg *em;
 213         ssize_t len;
 214         ulong flags;
 215
 216         n = (unsigned long) filp->private_data;
 217         if (n != MINOR_ERR)
 218                 return -EFAULT;
 219
 220         spin_lock_irqsave(&emsgs_lock, flags);
 221
 222         for (;;) {
 223                 em = emsgs + emsgs_head_idx;
 224                 if ((em->flags & EMFL_VALID) != 0)
 225                         break;
 226                 if (filp->f_flags & O_NDELAY) {
 227                         spin_unlock_irqrestore(&emsgs_lock, flags);
 228                         return -EAGAIN;
 229                 }
 230                 nblocked_emsgs_readers++;
 231
 232                 spin_unlock_irqrestore(&emsgs_lock, flags);
 233
 234                 n = wait_for_completion_interruptible(&emsgs_comp);
 235
 236                 spin_lock_irqsave(&emsgs_lock, flags);
 237
 238                 nblocked_emsgs_readers--;
 239
 240                 if (n) {
 241                         spin_unlock_irqrestore(&emsgs_lock, flags);
 242                         return -ERESTARTSYS;
 243                 }
 244         }
 245         if (em->len > cnt) {
 246                 spin_unlock_irqrestore(&emsgs_lock, flags);
 247                 return -EAGAIN;
 248         }
 249         mp = em->msg;
 250         len = em->len;
 251         em->msg = NULL;
 252         em->flags &= ~EMFL_VALID;
 253
 254         emsgs_head_idx++;
 255         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 256
 257         spin_unlock_irqrestore(&emsgs_lock, flags);
 258
 259         n = copy_to_user(buf, mp, len);
 260         kfree(mp);
 261         return n == 0 ? len : -EFAULT;
 262 }
 263
 264 static const struct file_operations aoe_fops = {
 265         .write = aoechr_write,
 266         .read = aoechr_read,
 267         .open = aoechr_open,
 268         .release = aoechr_rel,
 269         .owner = THIS_MODULE,
 270         .llseek = noop_llseek,
 271 };
 272
 273 static char *aoe_devnode(struct device *dev, umode_t *mode)
 274 {
 275         return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 276 }
 277
 278 int __init
 279 aoechr_init(void)
 280 {
 281         int n, i;
 282
 283         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 284         if (n < 0) {
 285                 printk(KERN_ERR "aoe: can't register char device\n");
 286                 return n;
 287         }
 288         init_completion(&emsgs_comp);
 289         spin_lock_init(&emsgs_lock);
 290         aoe_class = class_create(THIS_MODULE, "aoe");
 291         if (IS_ERR(aoe_class)) {
 292                 unregister_chrdev(AOE_MAJOR, "aoechr");
 293                 return PTR_ERR(aoe_class);
 294         }
 295         aoe_class->devnode = aoe_devnode;
 296
 297         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 298                 device_create(aoe_class, NULL,
 299                               MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
 300                               chardevs[i].name);
 301
 302         return 0;
 303 }
 304
 305 void
 306 aoechr_exit(void)
 307 {
 308         int i;
 309
 310         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 311                 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 312         class_destroy(aoe_class);
 313         unregister_chrdev(AOE_MAJOR, "aoechr");
 314 }
 315