[PATCH] drivers: memory_open cleanup - lookup minor device number from devlist

[Adriano dos Santos Fernandes <adrianosf@uol.com.br>]

memory_open ignores devlist and does a switch for each item, duplicating 
code
and conditional definitions.

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

Signed-off-by: Adriano dos Santos Fernandes <adrianosf@uol.com.br>
---

 drivers/char/mem.c |  115 
++++++++++++++++++++-------------------------------
 1 files changed, 45 insertions(+), 70 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 8f05c38..9e350f2 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -861,59 +861,58 @@ 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;
 }
@@ -922,30 +921,6 @@ 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)