drivers/block/aoe/aoechr.c

   1 /* Copyright (c) 2012 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
  43 /* A ring buffer of error messages, to be read through
  44  * "/dev/etherd/err".  When no messages are present,
  45  * readers will block waiting for messages to appear.
  46  */
  47 static struct ErrMsg emsgs[NMSG];
  48 static int emsgs_head_idx, emsgs_tail_idx;
  49 static struct completion emsgs_comp;
  50 static spinlock_t emsgs_lock;
  51 static int nblocked_emsgs_readers;
  52
  53 static struct aoe_chardev chardevs[] = {
  54         { MINOR_ERR, "err" },
  55         { MINOR_DISCOVER, "discover" },
  56         { MINOR_INTERFACES, "interfaces" },
  57         { MINOR_REVALIDATE, "revalidate" },
  58         { MINOR_FLUSH, "flush" },
  59 };
  60
  61 static char *aoe_devnode(const struct device *dev, umode_t *mode)
  62 {
  63         return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
  64 }
  65
  66 static const struct class aoe_class = {
  67         .name = "aoe",
  68         .devnode = aoe_devnode,
  69 };
  70
  71 static int
  72 discover(void)
  73 {
  74         aoecmd_cfg(0xffff, 0xff);
  75         return 0;
  76 }
  77
  78 static int
  79 interfaces(const char __user *str, size_t size)
  80 {
  81         if (set_aoe_iflist(str, size)) {
  82                 printk(KERN_ERR
  83                         "aoe: could not set interface list: too many interfaces\n");
  84                 return -EINVAL;
  85         }
  86         return 0;
  87 }
  88
  89 static int
  90 revalidate(const char __user *str, size_t size)
  91 {
  92         int major, minor, n;
  93         ulong flags;
  94         struct aoedev *d;
  95         struct sk_buff *skb;
  96         char buf[16];
  97
  98         if (size >= sizeof buf)
  99                 return -EINVAL;
 100         buf[sizeof buf - 1] = '\0';
 101         if (copy_from_user(buf, str, size))
 102                 return -EFAULT;
 103
 104         n = sscanf(buf, "e%d.%d", &major, &minor);
 105         if (n != 2) {
 106                 pr_err("aoe: invalid device specification %s\n", buf);
 107                 return -EINVAL;
 108         }
 109         d = aoedev_by_aoeaddr(major, minor, 0);
 110         if (!d)
 111                 return -EINVAL;
 112         spin_lock_irqsave(&d->lock, flags);
 113         aoecmd_cleanslate(d);
 114         aoecmd_cfg(major, minor);
 115 loop:
 116         skb = aoecmd_ata_id(d);
 117         spin_unlock_irqrestore(&d->lock, flags);
 118         /* try again if we are able to sleep a bit,
 119          * otherwise give up this revalidation
 120          */
 121         if (!skb && !msleep_interruptible(250)) {
 122                 spin_lock_irqsave(&d->lock, flags);
 123                 goto loop;
 124         }
 125         aoedev_put(d);
 126         if (skb) {
 127                 struct sk_buff_head queue;
 128                 __skb_queue_head_init(&queue);
 129                 __skb_queue_tail(&queue, skb);
 130                 aoenet_xmit(&queue);
 131         }
 132         return 0;
 133 }
 134
 135 void
 136 aoechr_error(char *msg)
 137 {
 138         struct ErrMsg *em;
 139         char *mp;
 140         ulong flags, n;
 141
 142         n = strlen(msg);
 143
 144         spin_lock_irqsave(&emsgs_lock, flags);
 145
 146         em = emsgs + emsgs_tail_idx;
 147         if ((em->flags & EMFL_VALID)) {
 148 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 149                 return;
 150         }
 151
 152         mp = kmemdup(msg, n, GFP_ATOMIC);
 153         if (!mp)
 154                 goto bail;
 155
 156         em->msg = mp;
 157         em->flags |= EMFL_VALID;
 158         em->len = n;
 159
 160         emsgs_tail_idx++;
 161         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 162
 163         spin_unlock_irqrestore(&emsgs_lock, flags);
 164
 165         if (nblocked_emsgs_readers)
 166                 complete(&emsgs_comp);
 167 }
 168
 169 static ssize_t
 170 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 171 {
 172         int ret = -EINVAL;
 173
 174         switch ((unsigned long) filp->private_data) {
 175         default:
 176                 printk(KERN_INFO "aoe: can't write to that file.\n");
 177                 break;
 178         case MINOR_DISCOVER:
 179                 ret = discover();
 180                 break;
 181         case MINOR_INTERFACES:
 182                 ret = interfaces(buf, cnt);
 183                 break;
 184         case MINOR_REVALIDATE:
 185                 ret = revalidate(buf, cnt);
 186                 break;
 187         case MINOR_FLUSH:
 188                 ret = aoedev_flush(buf, cnt);
 189                 break;
 190         }
 191         if (ret == 0)
 192                 ret = cnt;
 193         return ret;
 194 }
 195
 196 static int
 197 aoechr_open(struct inode *inode, struct file *filp)
 198 {
 199         int n, i;
 200
 201         mutex_lock(&aoechr_mutex);
 202         n = iminor(inode);
 203         filp->private_data = (void *) (unsigned long) n;
 204
 205         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 206                 if (chardevs[i].minor == n) {
 207                         mutex_unlock(&aoechr_mutex);
 208                         return 0;
 209                 }
 210         mutex_unlock(&aoechr_mutex);
 211         return -EINVAL;
 212 }
 213
 214 static int
 215 aoechr_rel(struct inode *inode, struct file *filp)
 216 {
 217         return 0;
 218 }
 219
 220 static ssize_t
 221 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 222 {
 223         unsigned long n;
 224         char *mp;
 225         struct ErrMsg *em;
 226         ssize_t len;
 227         ulong flags;
 228
 229         n = (unsigned long) filp->private_data;
 230         if (n != MINOR_ERR)
 231                 return -EFAULT;
 232
 233         spin_lock_irqsave(&emsgs_lock, flags);
 234
 235         for (;;) {
 236                 em = emsgs + emsgs_head_idx;
 237                 if ((em->flags & EMFL_VALID) != 0)
 238                         break;
 239                 if (filp->f_flags & O_NDELAY) {
 240                         spin_unlock_irqrestore(&emsgs_lock, flags);
 241                         return -EAGAIN;
 242                 }
 243                 nblocked_emsgs_readers++;
 244
 245                 spin_unlock_irqrestore(&emsgs_lock, flags);
 246
 247                 n = wait_for_completion_interruptible(&emsgs_comp);
 248
 249                 spin_lock_irqsave(&emsgs_lock, flags);
 250
 251                 nblocked_emsgs_readers--;
 252
 253                 if (n) {
 254                         spin_unlock_irqrestore(&emsgs_lock, flags);
 255                         return -ERESTARTSYS;
 256                 }
 257         }
 258         if (em->len > cnt) {
 259                 spin_unlock_irqrestore(&emsgs_lock, flags);
 260                 return -EAGAIN;
 261         }
 262         mp = em->msg;
 263         len = em->len;
 264         em->msg = NULL;
 265         em->flags &= ~EMFL_VALID;
 266
 267         emsgs_head_idx++;
 268         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 269
 270         spin_unlock_irqrestore(&emsgs_lock, flags);
 271
 272         n = copy_to_user(buf, mp, len);
 273         kfree(mp);
 274         return n == 0 ? len : -EFAULT;
 275 }
 276
 277 static const struct file_operations aoe_fops = {
 278         .write = aoechr_write,
 279         .read = aoechr_read,
 280         .open = aoechr_open,
 281         .release = aoechr_rel,
 282         .owner = THIS_MODULE,
 283         .llseek = noop_llseek,
 284 };
 285
 286 int __init
 287 aoechr_init(void)
 288 {
 289         int n, i;
 290
 291         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 292         if (n < 0) {
 293                 printk(KERN_ERR "aoe: can't register char device\n");
 294                 return n;
 295         }
 296         init_completion(&emsgs_comp);
 297         spin_lock_init(&emsgs_lock);
 298         n = class_register(&aoe_class);
 299         if (n) {
 300                 unregister_chrdev(AOE_MAJOR, "aoechr");
 301                 return n;
 302         }
 303
 304         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 305                 device_create(&aoe_class, NULL,
 306                               MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
 307                               chardevs[i].name);
 308
 309         return 0;
 310 }
 311
 312 void
 313 aoechr_exit(void)
 314 {
 315         int i;
 316
 317         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 318                 device_destroy(&aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 319         class_unregister(&aoe_class);
 320         unregister_chrdev(AOE_MAJOR, "aoechr");
 321 }
 322