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