drivers/block/aoe/aoechr.c

   1 /* Copyright (c) 2004 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 "aoe.h"
  10
  11 enum {
  12         //MINOR_STAT = 1, (moved to sysfs)
  13         MINOR_ERR = 2,
  14         MINOR_DISCOVER,
  15         MINOR_INTERFACES,
  16         MSGSZ = 2048,
  17         NARGS = 10,
  18         NMSG = 100,             /* message backlog to retain */
  19 };
  20
  21 struct aoe_chardev {
  22         ulong minor;
  23         char name[32];
  24 };
  25
  26 enum { EMFL_VALID = 1 };
  27
  28 struct ErrMsg {
  29         short flags;
  30         short len;
  31         char *msg;
  32 };
  33
  34 static struct ErrMsg emsgs[NMSG];
  35 static int emsgs_head_idx, emsgs_tail_idx;
  36 static struct semaphore emsgs_sema;
  37 static spinlock_t emsgs_lock;
  38 static int nblocked_emsgs_readers;
  39 static struct class_simple *aoe_class;
  40 static struct aoe_chardev chardevs[] = {
  41         { MINOR_ERR, "err" },
  42         { MINOR_DISCOVER, "discover" },
  43         { MINOR_INTERFACES, "interfaces" },
  44 };
  45
  46 static int
  47 discover(void)
  48 {
  49         aoecmd_cfg(0xffff, 0xff);
  50         return 0;
  51 }
  52
  53 static int
  54 interfaces(const char __user *str, size_t size)
  55 {
  56         if (set_aoe_iflist(str, size)) {
  57                 printk(KERN_CRIT
  58                        "%s: could not set interface list: %s\n",
  59                        __FUNCTION__, "too many interfaces");
  60                 return -EINVAL;
  61         }
  62         return 0;
  63 }
  64
  65 void
  66 aoechr_error(char *msg)
  67 {
  68         struct ErrMsg *em;
  69         char *mp;
  70         ulong flags, n;
  71
  72         n = strlen(msg);
  73
  74         spin_lock_irqsave(&emsgs_lock, flags);
  75
  76         em = emsgs + emsgs_tail_idx;
  77         if ((em->flags & EMFL_VALID)) {
  78 bail:           spin_unlock_irqrestore(&emsgs_lock, flags);
  79                 return;
  80         }
  81
  82         mp = kmalloc(n, GFP_ATOMIC);
  83         if (mp == NULL) {
  84                 printk(KERN_CRIT "aoe: aoechr_error: allocation failure, len=%ld\n", n);
  85                 goto bail;
  86         }
  87
  88         memcpy(mp, msg, n);
  89         em->msg = mp;
  90         em->flags |= EMFL_VALID;
  91         em->len = n;
  92
  93         emsgs_tail_idx++;
  94         emsgs_tail_idx %= ARRAY_SIZE(emsgs);
  95
  96         spin_unlock_irqrestore(&emsgs_lock, flags);
  97
  98         if (nblocked_emsgs_readers)
  99                 up(&emsgs_sema);
 100 }
 101
 102 static ssize_t
 103 aoechr_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *offp)
 104 {
 105         int ret = -EINVAL;
 106
 107         switch ((unsigned long) filp->private_data) {
 108         default:
 109                 printk(KERN_INFO "aoe: aoechr_write: can't write to that file.\n");
 110                 break;
 111         case MINOR_DISCOVER:
 112                 ret = discover();
 113                 break;
 114         case MINOR_INTERFACES:
 115                 ret = interfaces(buf, cnt);
 116                 break;
 117         }
 118         if (ret == 0)
 119                 ret = cnt;
 120         return ret;
 121 }
 122
 123 static int
 124 aoechr_open(struct inode *inode, struct file *filp)
 125 {
 126         int n, i;
 127
 128         n = MINOR(inode->i_rdev);
 129         filp->private_data = (void *) (unsigned long) n;
 130
 131         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 132                 if (chardevs[i].minor == n)
 133                         return 0;
 134         return -EINVAL;
 135 }
 136
 137 static int
 138 aoechr_rel(struct inode *inode, struct file *filp)
 139 {
 140         return 0;
 141 }
 142
 143 static ssize_t
 144 aoechr_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
 145 {
 146         unsigned long n;
 147         char *mp;
 148         struct ErrMsg *em;
 149         ssize_t len;
 150         ulong flags;
 151
 152         n = (unsigned long) filp->private_data;
 153         switch (n) {
 154         case MINOR_ERR:
 155                 spin_lock_irqsave(&emsgs_lock, flags);
 156 loop:
 157                 em = emsgs + emsgs_head_idx;
 158                 if ((em->flags & EMFL_VALID) == 0) {
 159                         if (filp->f_flags & O_NDELAY) {
 160                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 161                                 return -EAGAIN;
 162                         }
 163                         nblocked_emsgs_readers++;
 164
 165                         spin_unlock_irqrestore(&emsgs_lock, flags);
 166
 167                         n = down_interruptible(&emsgs_sema);
 168
 169                         spin_lock_irqsave(&emsgs_lock, flags);
 170
 171                         nblocked_emsgs_readers--;
 172
 173                         if (n) {
 174                                 spin_unlock_irqrestore(&emsgs_lock, flags);
 175                                 return -ERESTARTSYS;
 176                         }
 177                         goto loop;
 178                 }
 179                 if (em->len > cnt) {
 180                         spin_unlock_irqrestore(&emsgs_lock, flags);
 181                         return -EAGAIN;
 182                 }
 183                 mp = em->msg;
 184                 len = em->len;
 185                 em->msg = NULL;
 186                 em->flags &= ~EMFL_VALID;
 187
 188                 emsgs_head_idx++;
 189                 emsgs_head_idx %= ARRAY_SIZE(emsgs);
 190
 191                 spin_unlock_irqrestore(&emsgs_lock, flags);
 192
 193                 n = copy_to_user(buf, mp, len);
 194                 kfree(mp);
 195                 return n == 0 ? len : -EFAULT;
 196         default:
 197                 return -EFAULT;
 198         }
 199 }
 200
 201 static struct file_operations aoe_fops = {
 202         .write = aoechr_write,
 203         .read = aoechr_read,
 204         .open = aoechr_open,
 205         .release = aoechr_rel,
 206         .owner = THIS_MODULE,
 207 };
 208
 209 int __init
 210 aoechr_init(void)
 211 {
 212         int n, i;
 213
 214         n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 215         if (n < 0) {
 216                 printk(KERN_ERR "aoe: aoechr_init: can't register char device\n");
 217                 return n;
 218         }
 219         sema_init(&emsgs_sema, 0);
 220         spin_lock_init(&emsgs_lock);
 221         aoe_class = class_simple_create(THIS_MODULE, "aoe");
 222         if (IS_ERR(aoe_class)) {
 223                 unregister_chrdev(AOE_MAJOR, "aoechr");
 224                 return PTR_ERR(aoe_class);
 225         }
 226         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 227                 class_simple_device_add(aoe_class,
 228                                         MKDEV(AOE_MAJOR, chardevs[i].minor),
 229                                         NULL, chardevs[i].name);
 230
 231         return 0;
 232 }
 233
 234 void
 235 aoechr_exit(void)
 236 {
 237         int i;
 238
 239         for (i = 0; i < ARRAY_SIZE(chardevs); ++i)
 240                 class_simple_device_remove(MKDEV(AOE_MAJOR, chardevs[i].minor));
 241         class_simple_destroy(aoe_class);
 242         unregister_chrdev(AOE_MAJOR, "aoechr");
 243 }
 244