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 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         aoecmd_cfg(major, minor);
 100 loop:
 101         skb = aoecmd_ata_id(d);
 102         spin_unlock_irqrestore(&d->lock, flags);
 103         /* try again if we are able to sleep a bit,
 104          * otherwise give up this revalidation
 105          */
 106         if (!skb && !msleep_interruptible(250)) {
 107                 spin_lock_irqsave(&d->lock, flags);
 108                 goto loop;
 109         }
 110         aoedev_put(d);
 111         if (skb) {
 112                 struct sk_buff_head queue;
 113                 __skb_queue_head_init(&queue);
 114                 __skb_queue_tail(&queue, skb);
 115                 aoenet_xmit(&queue);
 116         }
 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                 break;
 178         }
 179         if (ret == 0)
 180                 ret = cnt;
 181         return ret;
 182 }
 183
 184 static int
 185 aoechr_open(struct inode *inode, struct file *filp)
 186 {
 187         int n, i;
 188
 189         mutex_lock(&aoechr_mutex);
 190         n = iminor(inode);
 191         filp->private_data = (void *) (unsigned long) n;
 192
 193         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 194                 if (chardevs[i].minor == n) {
 195                         mutex_unlock(&aoechr_mutex);
 196                         return 0;
 197                 }
 198         mutex_unlock(&aoechr_mutex);
 199         return -EINVAL;
 200 }
 201
 202 static int
 203 aoechr_rel(struct inode *inode, struct file *filp)
 204 {
 205         return 0;
 206 }
 207
 208 static ssize_t
 209 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 210 {
 211         unsigned long n;
 212         char *mp;
 213         struct ErrMsg *em;
 214         ssize_t len;
 215         ulong flags;
 216
 217         n = (unsigned long) filp->private_data;
 218         if (n != MINOR_ERR)
 219                 return -EFAULT;
 220
 221         spin_lock_irqsave(&emsgs_lock, flags);
 222
 223         for (;;) {
 224                 em = emsgs + emsgs_head_idx;
 225                 if ((em->flags & EMFL_VALID) != 0)
 226                         break;
 227                 if (filp->f_flags & O_NDELAY) {
 228                         spin_unlock_irqrestore(&emsgs_lock, flags);
 229                         return -EAGAIN;
 230                 }
 231                 nblocked_emsgs_readers++;
 232
 233                 spin_unlock_irqrestore(&emsgs_lock, flags);
 234
 235                 n = wait_for_completion_interruptible(&emsgs_comp);
 236
 237                 spin_lock_irqsave(&emsgs_lock, flags);
 238
 239                 nblocked_emsgs_readers--;
 240
 241                 if (n) {
 242                         spin_unlock_irqrestore(&emsgs_lock, flags);
 243                         return -ERESTARTSYS;
 244                 }
 245         }
 246         if (em->len > cnt) {
 247                 spin_unlock_irqrestore(&emsgs_lock, flags);
 248                 return -EAGAIN;
 249         }
 250         mp = em->msg;
 251         len = em->len;
 252         em->msg = NULL;
 253         em->flags &= ~EMFL_VALID;
 254
 255         emsgs_head_idx++;
 256         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 257
 258         spin_unlock_irqrestore(&emsgs_lock, flags);
 259
 260         n = copy_to_user(buf, mp, len);
 261         kfree(mp);
 262         return n == 0 ? len : -EFAULT;
 263 }
 264
 265 static const struct file_operations aoe_fops = {
 266         .write = aoechr_write,
 267         .read = aoechr_read,
 268         .open = aoechr_open,
 269         .release = aoechr_rel,
 270         .owner = THIS_MODULE,
 271         .llseek = noop_llseek,
 272 };
 273
 274 static char *aoe_devnode(struct device *dev, umode_t *mode)
 275 {
 276         return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 277 }
 278
 279 int __init
 280 aoechr_init(void)
 281 {
 282         int n, i;
 283
 284         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 285         if (n < 0) {
 286                 printk(KERN_ERR "aoe: can't register char device\n");
 287                 return n;
 288         }
 289         init_completion(&emsgs_comp);
 290         spin_lock_init(&emsgs_lock);
 291         aoe_class = class_create(THIS_MODULE, "aoe");
 292         if (IS_ERR(aoe_class)) {
 293                 unregister_chrdev(AOE_MAJOR, "aoechr");
 294                 return PTR_ERR(aoe_class);
 295         }
 296         aoe_class->devnode = aoe_devnode;
 297
 298         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 299                 device_create(aoe_class, NULL,
 300                               MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
 301                               chardevs[i].name);
 302
 303         return 0;
 304 }
 305
 306 void
 307 aoechr_exit(void)
 308 {
 309         int i;
 310
 311         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 312                 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 313         class_destroy(aoe_class);
 314         unregister_chrdev(AOE_MAJOR, "aoechr");
 315 }
 316