[PATCH 06/20] mem_class: use minor as index instead of searching the array

Greg Kroah-Hartman
2009-09-15T19:15:13Z

From: Kay Sievers <kay.sievers@vrfy.org>

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 | 82 +++++++++++++++++++++++++--------------------------
1 files changed, 40 insertions(+), 42 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 645237b..bed3503 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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;
}
--
1.6.4.2