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 = kmalloc(n, GFP_ATOMIC);
 143         if (mp == NULL) {
 144                 printk(KERN_ERR "aoe: allocation failure, len=%ld\n", n);
 145                 goto bail;
 146         }
 147
 148         memcpy(mp, msg, n);
 149         em->msg = mp;
 150         em->flags |= EMFL_VALID;
 151         em->len = n;
 152
 153         emsgs_tail_idx++;
 154         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
 155
 156         spin_unlock_irqrestore(&emsgs_lock, flags);
 157
 158         if (nblocked_emsgs_readers)
 159                 complete(&emsgs_comp);
 160 }
 161
 162 static ssize_t
 163 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 164 {
 165         int ret = -EINVAL;
 166
 167         switch ((unsigned long) filp->private_data) {
 168         default:
 169                 printk(KERN_INFO "aoe: can't write to that file.\n");
 170                 break;
 171         case MINOR_DISCOVER:
 172                 ret = discover();
 173                 break;
 174         case MINOR_INTERFACES:
 175                 ret = interfaces(buf, cnt);
 176                 break;
 177         case MINOR_REVALIDATE:
 178                 ret = revalidate(buf, cnt);
 179                 break;
 180         case MINOR_FLUSH:
 181                 ret = aoedev_flush(buf, cnt);
 182                 break;
 183         }
 184         if (ret == 0)
 185                 ret = cnt;
 186         return ret;
 187 }
 188
 189 static int
 190 aoechr_open(struct inode *inode, struct file *filp)
 191 {
 192         int n, i;
 193
 194         mutex_lock(&aoechr_mutex);
 195         n = iminor(inode);
 196         filp->private_data = (void *) (unsigned long) n;
 197
 198         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 199                 if (chardevs[i].minor == n) {
 200                         mutex_unlock(&aoechr_mutex);
 201                         return 0;
 202                 }
 203         mutex_unlock(&aoechr_mutex);
 204         return -EINVAL;
 205 }
 206
 207 static int
 208 aoechr_rel(struct inode *inode, struct file *filp)
 209 {
 210         return 0;
 211 }
 212
 213 static ssize_t
 214 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 215 {
 216         unsigned long n;
 217         char *mp;
 218         struct ErrMsg *em;
 219         ssize_t len;
 220         ulong flags;
 221
 222         n = (unsigned long) filp->private_data;
 223         if (n != MINOR_ERR)
 224                 return -EFAULT;
 225
 226         spin_lock_irqsave(&emsgs_lock, flags);
 227
 228         for (;;) {
 229                 em = emsgs + emsgs_head_idx;
 230                 if ((em->flags & EMFL_VALID) != 0)
 231                         break;
 232                 if (filp->f_flags & O_NDELAY) {
 233                         spin_unlock_irqrestore(&emsgs_lock, flags);
 234                         return -EAGAIN;
 235                 }
 236                 nblocked_emsgs_readers++;
 237
 238                 spin_unlock_irqrestore(&emsgs_lock, flags);
 239
 240                 n = wait_for_completion_interruptible(&emsgs_comp);
 241
 242                 spin_lock_irqsave(&emsgs_lock, flags);
 243
 244                 nblocked_emsgs_readers--;
 245
 246                 if (n) {
 247                         spin_unlock_irqrestore(&emsgs_lock, flags);
 248                         return -ERESTARTSYS;
 249                 }
 250         }
 251         if (em->len > cnt) {
 252                 spin_unlock_irqrestore(&emsgs_lock, flags);
 253                 return -EAGAIN;
 254         }
 255         mp = em->msg;
 256         len = em->len;
 257         em->msg = NULL;
 258         em->flags &= ~EMFL_VALID;
 259
 260         emsgs_head_idx++;
 261         emsgs_head_idx %= ARRAY_SIZE(emsgs);
 262
 263         spin_unlock_irqrestore(&emsgs_lock, flags);
 264
 265         n = copy_to_user(buf, mp, len);
 266         kfree(mp);
 267         return n == 0 ? len : -EFAULT;
 268 }
 269
 270 static const struct file_operations aoe_fops = {
 271         .write = aoechr_write,
 272         .read = aoechr_read,
 273         .open = aoechr_open,
 274         .release = aoechr_rel,
 275         .owner = THIS_MODULE,
 276         .llseek = noop_llseek,
 277 };
 278
 279 static char *aoe_devnode(struct device *dev, umode_t *mode)
 280 {
 281         return kasprintf(GFP_KERNEL, "etherd/%s", dev_name(dev));
 282 }
 283
 284 int __init
 285 aoechr_init(void)
 286 {
 287         int n, i;
 288
 289         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 290         if (n < 0) {
 291                 printk(KERN_ERR "aoe: can't register char device\n");
 292                 return n;
 293         }
 294         init_completion(&emsgs_comp);
 295         spin_lock_init(&emsgs_lock);
 296         aoe_class = class_create(THIS_MODULE, "aoe");
 297         if (IS_ERR(aoe_class)) {
 298                 unregister_chrdev(AOE_MAJOR, "aoechr");
 299                 return PTR_ERR(aoe_class);
 300         }
 301         aoe_class->devnode = aoe_devnode;
 302
 303         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 304                 device_create(aoe_class, NULL,
 305                               MKDEV(AOE_MAJOR, chardevs[i].minor), NULL,
 306                               chardevs[i].name);
 307
 308         return 0;
 309 }
 310
 311 void
 312 aoechr_exit(void)
 313 {
 314         int i;
 315
 316         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 317                 device_destroy(aoe_class, MKDEV(AOE_MAJOR, chardevs[i].minor));
 318         class_destroy(aoe_class);
 319         unregister_chrdev(AOE_MAJOR, "aoechr");
 320 }
 321