mem_class: use minor as index instead of searching the array
Kay Sievers [Sat, 4 Jul 2009 14:51:29 +0000 (16:51 +0200)]
Declare the device list with the minor numbers as the index, which saves us from
searching for a matching list entry. Remove old devfs permissions declaration.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/mem.c

index 645237b..bed3503 100644 (file)
@@ -864,71 +864,67 @@ static const struct file_operations kmsg_fops = {
        .write =        kmsg_write,
 };
 
-static const struct {
-       unsigned int            minor;
-       char                    *name;
-       umode_t                 mode;
-       const struct file_operations    *fops;
-       struct backing_dev_info *dev_info;
-} devlist[] = { /* list of minor devices */
-       {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops,
-               &directly_mappable_cdev_bdi},
+static const struct memdev {
+       const char *name;
+       const struct file_operations *fops;
+       struct backing_dev_info *dev_info;
+} devlist[] = {
+       [ 1] = { "mem", &mem_fops, &directly_mappable_cdev_bdi },
 #ifdef CONFIG_DEVKMEM
-       {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops,
-               &directly_mappable_cdev_bdi},
+       [ 2] = { "kmem", &kmem_fops, &directly_mappable_cdev_bdi },
 #endif
-       {3, "null",    S_IRUGO | S_IWUGO,           &null_fops, NULL},
+       [ 3] = {"null", &null_fops, NULL },
 #ifdef CONFIG_DEVPORT
-       {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops, NULL},
+       [ 4] = { "port", &port_fops, NULL },
 #endif
-       {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops, &zero_bdi},
-       {7, "full",    S_IRUGO | S_IWUGO,           &full_fops, NULL},
-       {8, "random",  S_IRUGO | S_IWUSR,           &random_fops, NULL},
-       {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops, NULL},
-       {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops, NULL},
+       [ 5] = { "zero", &zero_fops, &zero_bdi },
+       [ 6] = { "full", &full_fops, NULL },
+       [ 7] = { "random", &random_fops, NULL },
+       [ 9] = { "urandom", &urandom_fops, NULL },
+       [11] = { "kmsg", &kmsg_fops, NULL },
 #ifdef CONFIG_CRASH_DUMP
-       {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops, NULL},
+       [12] = { "oldmem", &oldmem_fops, NULL },
 #endif
 };
 
 static int memory_open(struct inode *inode, struct file *filp)
 {
-       int ret = 0;
-       int i;
+       int minor;
+       const struct memdev *dev;
+       int ret = -ENXIO;
 
        lock_kernel();
 
-       for (i = 0; i < ARRAY_SIZE(devlist); i++) {
-               if (devlist[i].minor == iminor(inode)) {
-                       filp->f_op = devlist[i].fops;
-                       if (devlist[i].dev_info) {
-                               filp->f_mapping->backing_dev_info =
-                                       devlist[i].dev_info;
-                       }
+       minor = iminor(inode);
+       if (minor >= ARRAY_SIZE(devlist))
+               goto out;
 
-                       break;
-               }
-       }
+       dev = &devlist[minor];
+       if (!dev->fops)
+               goto out;
 
-       if (i == ARRAY_SIZE(devlist))
-               ret = -ENXIO;
-       else
-               if (filp->f_op && filp->f_op->open)
-                       ret = filp->f_op->open(inode, filp);
+       filp->f_op = dev->fops;
+       if (dev->dev_info)
+               filp->f_mapping->backing_dev_info = dev->dev_info;
 
+       if (dev->fops->open)
+               ret = dev->fops->open(inode, filp);
+       else
+               ret = 0;
+out:
        unlock_kernel();
        return ret;
 }
 
 static const struct file_operations memory_fops = {
-       .open           = memory_open,  /* just a selector for the real open */
+       .open           = memory_open,
 };
 
 static struct class *mem_class;
 
 static int __init chr_dev_init(void)
 {
-       int i;
+       int minor;
        int err;
 
        err = bdi_init(&zero_bdi);
@@ -939,10 +935,12 @@ static int __init chr_dev_init(void)
                printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 
        mem_class = class_create(THIS_MODULE, "mem");
-       for (i = 0; i < ARRAY_SIZE(devlist); i++)
-               device_create(mem_class, NULL,
-                             MKDEV(MEM_MAJOR, devlist[i].minor), NULL,
-                             devlist[i].name);
+       for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
+               if (!devlist[minor].name)
+                       continue;
+               device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
+                             NULL, devlist[minor].name);
+       }
 
        return 0;
 }