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 static struct class *aoe_class;
  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 int
  62 discover(void)
  63 {
  64         aoecmd_cfg(0xffff, 0xff);
  65         return 0;
  66 }
  67
  68 static int
  69 interfaces(const char __user *str, size_t size)
  70 {
  71         if (set_aoe_iflist(str, size)) {
  72                 printk(KERN_ERR
  73                         "aoe: could not set interface list: too many interfaces\n");
  74                 return -EINVAL;
  75         }
  76         return 0;
  77 }
  78
  79 static int
  80 revalidate(const char __user *str, size_t size)
  81 {
  82         int major, minor, n;
  83         ulong flags;
  84         struct aoedev *d;
  85         struct sk_buff *skb;
  86         char buf[16];
  87
  88         if (size >= sizeof buf)
  89                 return -EINVAL;
  90         buf[sizeof buf - 1] = '\0';
  91         if (copy_from_user(buf, str, size))
  92                 return -EFAULT;
  93
  94         n = sscanf(buf, "e%d.%d", &major, &minor);
  95         if (n != 2) {
  96                 pr_err("aoe: invalid device specification %s\n", buf);
  97                 return -EINVAL;
  98         }
  99         d = aoedev_by_aoeaddr(major, minor, 0);
 100         if (!d)
 101                 return -EINVAL;
 102         spin_lock_irqsave(&d->lock, flags);
 103         aoecmd_cleanslate(d);
 104         aoecmd_cfg(major, minor);
 105 loop:
 106         skb = aoecmd_ata_id(d);
 107         spin_unlock_irqrestore(&d->lock, flags);
 108         /* try again if we are able to sleep a bit,
 109          * otherwise give up this revalidation
 110          */
 111         if (!skb && !msleep_interruptible(250)) {
 112                 spin_lock_irqsave(&d->lock, flags);
 113                 goto loop;
 114         }
 115         aoedev_put(d);
 116         if (skb) {
 117                 struct sk_buff_head queue;
 118                 __skb_queue_head_init(&queue);
 119                 __skb_queue_tail(&queue, skb);
 120                 aoenet_xmit(&queue);
 121         }
 122         return 0;
 123 }
 124
 125 void
 126 aoechr_error(char *msg)
 127 {
 128         struct ErrMsg *em;
 129         char *mp;
 130         ulong flags, n;
 131
 132         n = strlen(msg);
 133
 134         spin_lock_irqsave(&emsgs_lock, flags);
 135
 136         em = emsgs + emsgs_tail_idx;
 137         if ((em->flags & EMFL_VALID)) {
 138 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
 139                 return;
 140         }
 141
 142         mp = kmemdup(msg, n, GFP_ATOMIC);
 143         if (mp == NULL) {
 144                 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
 145                 goto bail;
 146         }
 147
 148         em->msg = mp;
 149         em->flags |= EMFL_VALID;
 150         em->len = n;
 151
 152         emsgs_tail_idx++;
 153         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 154
 155         spin_unlock_irqrestore(&emsgs_lock, flags);
 156
 157         if (nblocked_emsgs_readers)
 158                 complete(&emsgs_comp);
 159 }
 160
 161 static ssize_t
 162 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 163 {
 164         int ret = -EINVAL;
 165
 166         switch ((unsigned long) filp->private_data) {
 167         default:
 168                 printk(KERN_INFO "aoe: can't write to that file.\n");
 169                 break;
 170         case MINOR_DISCOVER:
 171                 ret = discover();
 172                 break;
 173         case MINOR_INTERFACES:
 174                 ret = interfaces(buf, cnt);
 175                 break;
 176         case MINOR_REVALIDATE:
 177                 ret = revalidate(buf, cnt);
 178                 break;
 179         case MINOR_FLUSH:
 180                 ret = aoedev_flush(buf, cnt);
 181                 break;
 182         }
 183         if (ret == 0)
 184                 ret = cnt;
 185         return ret;
 186 }
 187
 188 static int
 189 aoechr_open(struct inode *inode, struct file *filp)
 190 {
 191         int n, i;
 192
 193         mutex_lock(&aoechr_mutex);
 194         n = iminor(inode);
 195         filp->private_data = (void *) (unsigned long) n;
 196
 197         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 198                 if (chardevs[i].minor == n) {
 199                         mutex_unlock(&aoechr_mutex);
 200                         return 0;
 201                 }
 202         mutex_unlock(&aoechr_mutex);
 203         return -EINVAL;
 204 }
 205
 206 static int
 207 aoechr_rel(struct inode *inode, struct file *filp)
 208 {
 209         return 0;
 210 }
 211
 212 static ssize_t
 213 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 214 {
 215         unsigned long n;
 216         char *mp;
 217         struct ErrMsg *em;
 218         ssize_t len;
 219         ulong flags;
 220
 221         n = (unsigned long) filp->private_data;
 222         if (n != MINOR_ERR)
 223                 return -EFAULT;
 224
 225         spin_lock_irqsave(&emsgs_lock, flags);
 226
 227         for (;;) {
 228                 em = emsgs + emsgs_head_idx;
 229                 if ((em->flags & EMFL_VALID) != 0)
 230                         break;
 231                 if (filp->f_flags & O_NDELAY) {
 232                         spin_unlock_irqrestore(&emsgs_lock, flags);
 233                         return -EAGAIN;
 234                 }
 235                 nblocked_emsgs_readers++;
 236
 237                 spin_unlock_irqrestore(&emsgs_lock, flags);
 238
 239                 n = wait_for_completion_interruptible(&emsgs_comp);
 240
 241                 spin_lock_irqsave(&emsgs_lock, flags);
 242
 243                 nblocked_emsgs_readers--;
 244
 245                 if (n) {
 246                         spin_unlock_irqrestore(&emsgs_lock, flags);
 247                         return -ERESTARTSYS;
 248                 }
 249         }
 250         if (em->len > cnt) {
 251                 spin_unlock_irqrestore(&emsgs_lock, flags);
 252                 return -EAGAIN;
 253         }
 254         mp = em->msg;
 255         len = em->len;
 256         em->msg = NULL;
 257         em->flags &= ~EMFL_VALID;
 258
 259         emsgs_head_idx++;
 260         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 261
 262         spin_unlock_irqrestore(&emsgs_lock, flags);
 263
 264         n = copy_to_user(buf, mp, len);
 265         kfree(mp);
 266         return n == 0 ? len : -EFAULT;
 267 }
 268
 269 static const struct file_operations aoe_fops = {
 270         .write = aoechr_write,
 271         .read = aoechr_read,
 272         .open = aoechr_open,
 273         .release = aoechr_rel,
 274         .owner = THIS_MODULE,
 275         .llseek = noop_llseek,
 276 };
 277
 278 static char *aoe_devnode(struct device *dev, umode_t *mode)
 279 {
 280         return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 281 }
 282
 283 int __init
 284 aoechr_init(void)
 285 {
 286         int n, i;
 287
 288         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 289         if (n < 0) {
 290                 printk(KERN_ERR "aoe: can't register char device\n");
 291                 return n;
 292         }
 293         init_completion(&emsgs_comp);
 294         spin_lock_init(&emsgs_lock);
 295         aoe_class = class_create(THIS_MODULE, "aoe");
 296         if (IS_ERR(aoe_class)) {
 297                 unregister_chrdev(AOE_MAJOR, "aoechr");
 298                 return PTR_ERR(aoe_class);
 299         }
 300         aoe_class->devnode = aoe_devnode;
 301
 302         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 303                 device_create(aoe_class, NULL,
 304                               MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
 305                               chardevs[i].name);
 306
 307         return 0;
 308 }
 309
 310 void
 311 aoechr_exit(void)
 312 {
 313         int i;
 314
 315         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 316                 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 317         class_destroy(aoe_class);
 318         unregister_chrdev(AOE_MAJOR, "aoechr");
 319 }
 320