Hi,
This patch restores the character device hash, which will is more
suitable to manage a large number of character devices.
I used the chance to add a grep-friendly prefix to the char_device
members.
bye, Roman
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/fs/char_dev.c linux-2.5-dev3/fs/char_dev.c
--- linux-2.5-dev2/fs/char_dev.c 2003-03-23 18:28:37.000000000 +0100
+++ linux-2.5-dev3/fs/char_dev.c 2003-03-23 19:09:13.000000000 +0100
@@ -23,10 +23,114 @@
/* serial module kmod load support */
struct tty_driver *get_tty_driver(kdev_t device);
-#define is_a_tty_dev(ma) (ma == TTY_MAJOR || ma == TTYAUX_MAJOR)
+#define isa_tty_dev(ma) (ma == TTY_MAJOR || ma == TTYAUX_MAJOR)
#define need_serial(ma,mi) (get_tty_driver(mk_kdev(ma,mi)) == NULL)
#endif
+#define HASH_BITS 6
+#define HASH_SIZE (1UL << HASH_BITS)
+#define HASH_MASK (HASH_SIZE-1)
+static struct list_head cdev_hashtable[HASH_SIZE];
+static spinlock_t cdev_lock = SPIN_LOCK_UNLOCKED;
+static kmem_cache_t *cdev_cachep;
+
+#define alloc_cdev() \
+ ((struct char_device *) kmem_cache_alloc(cdev_cachep, SLAB_KERNEL))
+#define destroy_cdev(cdev) kmem_cache_free(cdev_cachep, (cdev))
+
+static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
+{
+ struct char_device *cdev = (struct char_device *) foo;
+
+ if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+ SLAB_CTOR_CONSTRUCTOR)
+ memset(cdev, 0, sizeof(*cdev));
+}
+
+void __init cdev_cache_init(void)
+{
+ int i;
+ struct list_head *head = cdev_hashtable;
+
+ i = HASH_SIZE;
+ do {
+ INIT_LIST_HEAD(head);
+ head++;
+ i--;
+ } while (i);
+
+ cdev_cachep = kmem_cache_create("cdev_cache",
+ sizeof(struct char_device),
+ 0, SLAB_HWCACHE_ALIGN, init_once,
+ NULL);
+ if (!cdev_cachep)
+ panic("Cannot create cdev_cache SLAB cache");
+}
+
+/*
+ * Most likely _very_ bad one - but then it's hardly critical for small
+ * /dev and can be fixed when somebody will need really large one.
+ */
+static inline unsigned long hash(dev_t dev)
+{
+ unsigned long tmp = dev;
+ tmp = tmp + (tmp >> HASH_BITS) + (tmp >> HASH_BITS*2);
+ return tmp & HASH_MASK;
+}
+
+static struct char_device *cdfind(dev_t dev, struct list_head *head)
+{
+ struct list_head *p;
+ struct char_device *cdev;
+
+ list_for_each(p, head) {
+ cdev = list_entry(p, struct char_device, cd_hash);
+ if (cdev->cd_dev == dev) {
+ atomic_inc(&cdev->cd_count);
+ return cdev;
+ }
+ }
+ return NULL;
+}
+
+struct char_device *cdget(dev_t dev)
+{
+ struct list_head * head = cdev_hashtable + hash(dev);
+ struct char_device *cdev, *new_cdev;
+
+ spin_lock(&cdev_lock);
+ cdev = cdfind(dev, head);
+ spin_unlock(&cdev_lock);
+ if (cdev)
+ return cdev;
+
+ new_cdev = alloc_cdev();
+ if (!new_cdev)
+ return NULL;
+ atomic_set(&new_cdev->cd_count, 1);
+ new_cdev->cd_dev = dev;
+
+ spin_lock(&cdev_lock);
+ cdev = cdfind(dev, head);
+ if (!cdev) {
+ list_add(&new_cdev->cd_hash, head);
+ spin_unlock(&cdev_lock);
+ return new_cdev;
+ }
+ spin_unlock(&cdev_lock);
+ destroy_cdev(new_cdev);
+ return cdev;
+}
+
+void cdput(struct char_device *cdev)
+{
+ if (atomic_dec_and_lock(&cdev->cd_count, &cdev_lock)) {
+ list_del(&cdev->cd_hash);
+ spin_unlock(&cdev_lock);
+ destroy_cdev(cdev);
+ }
+}
+
struct device_struct {
const char * name;
struct file_operations * fops;
@@ -44,8 +148,7 @@
read_lock(&chrdevs_lock);
for (i = 0; i < MAX_CHRDEV ; i++) {
if (chrdevs[i].fops) {
- len += sprintf(page+len, "%3d %s\n",
- i, chrdevs[i].name);
+ len += sprintf(page+len, "%3d %s\n", i, chrdevs[i].name);
}
}
read_unlock(&chrdevs_lock);
@@ -53,14 +156,13 @@
}
/*
- * Return the function table of a device.
- * Load the driver if needed.
- * Increment the reference count of module in question.
- */
-static struct file_operations *
-get_chrfops(unsigned int major, unsigned int minor)
+ Return the function table of a device.
+ Load the driver if needed.
+ Increment the reference count of module in question.
+*/
+static struct file_operations * get_chrfops(unsigned int major, unsigned int minor)
{
- struct file_operations *ret;
+ struct file_operations *ret = NULL;
if (!major || major >= MAX_CHRDEV)
return NULL;
@@ -69,12 +171,10 @@
ret = fops_get(chrdevs[major].fops);
read_unlock(&chrdevs_lock);
#ifdef CONFIG_KMOD
- if (ret && is_a_tty_dev(major)) {
+ if (ret && isa_tty_dev(major)) {
lock_kernel();
if (need_serial(major,minor)) {
/* Force request_module anyway, but what for? */
- /* The reason is that we may have a driver for
- /dev/tty1 already, but need one for /dev/ttyS1. */
fops_put(ret);
ret = NULL;
}
@@ -93,8 +193,7 @@
return ret;
}
-int register_chrdev(unsigned int major, const char *name,
- struct file_operations *fops)
+int register_chrdev(unsigned int major, const char * name, struct file_operations *fops)
{
if (major == 0) {
write_lock(&chrdevs_lock);
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/fs/dcache.c linux-2.5-dev3/fs/dcache.c
--- linux-2.5-dev2/fs/dcache.c 2003-03-23 18:08:54.000000000 +0100
+++ linux-2.5-dev3/fs/dcache.c 2003-03-23 18:30:01.000000000 +0100
@@ -1563,6 +1563,7 @@
EXPORT_SYMBOL(d_genocide);
extern void bdev_cache_init(void);
+extern void cdev_cache_init(void);
void __init vfs_caches_init(unsigned long mempages)
{
@@ -1583,4 +1584,5 @@
files_init(mempages);
mnt_init(mempages);
bdev_cache_init();
+ cdev_cache_init();
}
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/fs/devfs/base.c linux-2.5-dev3/fs/devfs/base.c
--- linux-2.5-dev2/fs/devfs/base.c 2003-03-23 18:08:54.000000000 +0100
+++ linux-2.5-dev3/fs/devfs/base.c 2003-03-23 18:30:01.000000000 +0100
@@ -2016,6 +2016,7 @@
if ( S_ISCHR (de->mode) )
{
inode->i_rdev = to_kdev_t(de->u.cdev.dev);
+ inode->i_cdev = cdget(de->u.cdev.dev);
}
else if ( S_ISBLK (de->mode) )
{
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/fs/inode.c linux-2.5-dev3/fs/inode.c
--- linux-2.5-dev2/fs/inode.c 2003-03-23 18:20:14.000000000 +0100
+++ linux-2.5-dev3/fs/inode.c 2003-03-23 18:30:01.000000000 +0100
@@ -128,6 +128,7 @@
memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
inode->i_pipe = NULL;
inode->i_bdev = NULL;
+ inode->i_cdev = NULL;
inode->i_rdev = to_kdev_t(0);
inode->i_security = NULL;
if (security_inode_alloc(inode)) {
@@ -241,6 +242,10 @@
inode->i_sb->s_op->clear_inode(inode);
if (inode->i_bdev)
bd_forget(inode);
+ else if (inode->i_cdev) {
+ cdput(inode->i_cdev);
+ inode->i_cdev = NULL;
+ }
inode->i_state = I_CLEAR;
}
@@ -1310,6 +1315,7 @@
if (S_ISCHR(mode)) {
inode->i_fop = &def_chr_fops;
inode->i_rdev = to_kdev_t(rdev);
+ inode->i_cdev = cdget(rdev);
} else if (S_ISBLK(mode)) {
inode->i_fop = &def_blk_fops;
inode->i_rdev = to_kdev_t(rdev);
@@ -1318,6 +1324,5 @@
else if (S_ISSOCK(mode))
inode->i_fop = &bad_sock_fops;
else
- printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n",
- mode);
+ printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o)\n", mode);
}
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/include/linux/fs.h linux-2.5-dev3/include/linux/fs.h
--- linux-2.5-dev2/include/linux/fs.h 2003-03-23 18:20:14.000000000 +0100
+++ linux-2.5-dev3/include/linux/fs.h 2003-03-23 19:01:56.000000000 +0100
@@ -331,6 +331,12 @@
struct address_space *assoc_mapping; /* ditto */
};
+struct char_device {
+ struct list_head cd_hash;
+ atomic_t cd_count;
+ dev_t cd_dev;
+};
+
struct block_device {
struct list_head bd_hash;
atomic_t bd_count;
@@ -382,6 +388,7 @@
struct list_head i_devices;
struct pipe_inode_info *i_pipe;
struct block_device *i_bdev;
+ struct char_device *i_cdev;
unsigned long i_dnotify_mask; /* Directory notify events */
struct dnotify_struct *i_dnotify; /* for directory notifications */
@@ -1039,6 +1046,8 @@
extern int bd_acquire(struct inode *inode);
extern void bd_forget(struct inode *inode);
extern void bdput(struct block_device *);
+extern struct char_device *cdget(dev_t);
+extern void cdput(struct char_device *);
extern int blkdev_open(struct inode *, struct file *);
extern int blkdev_close(struct inode *, struct file *);
extern struct file_operations def_blk_fops;
diff -Nur -X /opt/home/roman/nodiff linux-2.5-dev2/kernel/ksyms.c linux-2.5-dev3/kernel/ksyms.c
--- linux-2.5-dev2/kernel/ksyms.c 2003-03-23 18:08:56.000000000 +0100
+++ linux-2.5-dev3/kernel/ksyms.c 2003-03-23 18:30:01.000000000 +0100
@@ -203,6 +203,8 @@
EXPORT_SYMBOL(set_blocksize);
EXPORT_SYMBOL(sb_set_blocksize);
EXPORT_SYMBOL(sb_min_blocksize);
+EXPORT_SYMBOL(cdget);
+EXPORT_SYMBOL(cdput);
EXPORT_SYMBOL(bdget);
EXPORT_SYMBOL(bdput);
EXPORT_SYMBOL(bd_claim);
-
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This archive was generated by hypermail 2b29 : Sun Mar 23 2003 - 22:00:46 EST