drivers/char/mem.c: memory_open() cleanup: lookup minor device number from devlist
Adriano dos Santos Fernandes [Wed, 17 Jun 2009 23:27:48 +0000 (16:27 -0700)]
memory_open() ignores devlist and does a switch for each item, duplicating
code and conditional definitions.

Clean it up by adding backing_dev_info to devlist and use it to lookup for
the minor device.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Adriano dos Santos Fernandes <adrianosf@uol.com.br>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/mem.c

index f96d0be..afa8813 100644 (file)
@@ -863,59 +863,58 @@ static const struct file_operations kmsg_fops = {
        .write =        kmsg_write,
 };
 
-static int memory_open(struct inode * inode, struct file * filp)
-{
-       int ret = 0;
-
-       lock_kernel();
-       switch (iminor(inode)) {
-               case 1:
-                       filp->f_op = &mem_fops;
-                       filp->f_mapping->backing_dev_info =
-                               &directly_mappable_cdev_bdi;
-                       break;
+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},
 #ifdef CONFIG_DEVKMEM
-               case 2:
-                       filp->f_op = &kmem_fops;
-                       filp->f_mapping->backing_dev_info =
-                               &directly_mappable_cdev_bdi;
-                       break;
+       {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops,
+               &directly_mappable_cdev_bdi},
 #endif
-               case 3:
-                       filp->f_op = &null_fops;
-                       break;
+       {3, "null",    S_IRUGO | S_IWUGO,           &null_fops, NULL},
 #ifdef CONFIG_DEVPORT
-               case 4:
-                       filp->f_op = &port_fops;
-                       break;
+       {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops, NULL},
 #endif
-               case 5:
-                       filp->f_mapping->backing_dev_info = &zero_bdi;
-                       filp->f_op = &zero_fops;
-                       break;
-               case 7:
-                       filp->f_op = &full_fops;
-                       break;
-               case 8:
-                       filp->f_op = &random_fops;
-                       break;
-               case 9:
-                       filp->f_op = &urandom_fops;
-                       break;
-               case 11:
-                       filp->f_op = &kmsg_fops;
-                       break;
+       {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},
 #ifdef CONFIG_CRASH_DUMP
-               case 12:
-                       filp->f_op = &oldmem_fops;
-                       break;
+       {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops, NULL},
 #endif
-               default:
-                       unlock_kernel();
-                       return -ENXIO;
+};
+
+static int memory_open(struct inode *inode, struct file *filp)
+{
+       int ret = 0;
+       int i;
+
+       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;
+                       }
+
+                       break;
+               }
        }
-       if (filp->f_op && filp->f_op->open)
-               ret = filp->f_op->open(inode,filp);
+
+       if (i == ARRAY_SIZE(devlist))
+               ret = -ENXIO;
+       else
+               if (filp->f_op && filp->f_op->open)
+                       ret = filp->f_op->open(inode, filp);
+
        unlock_kernel();
        return ret;
 }
@@ -924,30 +923,6 @@ static const struct file_operations memory_fops = {
        .open           = memory_open,  /* just a selector for the real open */
 };
 
-static const struct {
-       unsigned int            minor;
-       char                    *name;
-       umode_t                 mode;
-       const struct file_operations    *fops;
-} devlist[] = { /* list of minor devices */
-       {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
-#ifdef CONFIG_DEVKMEM
-       {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
-#endif
-       {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
-#ifdef CONFIG_DEVPORT
-       {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
-#endif
-       {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
-       {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
-       {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
-       {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
-       {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
-#ifdef CONFIG_CRASH_DUMP
-       {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
-#endif
-};
-
 static struct class *mem_class;
 
 static int __init chr_dev_init(void)