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