Commit 8a932f73 authored by Logan Gunthorpe's avatar Logan Gunthorpe Committed by Greg Kroah-Hartman
Browse files

char_dev: order /proc/devices by major number 



Presently, the order of the char devices listed in /proc/devices is not
entirely sequential. If a char device has a major number greater than
CHRDEV_MAJOR_HASH_SIZE (255), it will be ordered as if its major were
module 255. For example, 511 appears after 1.

This patch cleans that up and prints each major number in the correct
order, regardless of where they are stored in the hash table.

In order to do this, we introduce CHRDEV_MAJOR_MAX as an artificial
limit (chosen to be 511). It will then print all devices in major
order number from 0 to the maximum.

Signed-off-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a5d31a3f

fs/char_dev.c

+13 −4
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ static struct kobj_map *cdev_map; 


static DEFINE_MUTEX(chrdevs_lock);



#define CHRDEV_MAJOR_HASH_SIZE 255



static struct char_device_struct {

	struct char_device_struct *next;

	unsigned int major;
@@ -49,12 +51,12 @@ void chrdev_show(struct seq_file *f, off_t offset) 
{

	struct char_device_struct *cd;



	if (offset < CHRDEV_MAJOR_HASH_SIZE) {

	mutex_lock(&chrdevs_lock);

		for (cd = chrdevs[offset]; cd; cd = cd->next)

	for (cd = chrdevs[major_to_index(offset)]; cd; cd = cd->next) {

		if (cd->major == offset)

			seq_printf(f, "%3d %s\n", cd->major, cd->name);

		mutex_unlock(&chrdevs_lock);

	}

	mutex_unlock(&chrdevs_lock);

}



#endif /* CONFIG_PROC_FS */
@@ -117,6 +119,13 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor, 
		major = ret;

	}



	if (major >= CHRDEV_MAJOR_MAX) {

		pr_err("CHRDEV \"%s\" major requested (%d) is greater than the maximum (%d)\n",

		       name, major, CHRDEV_MAJOR_MAX);

		ret = -EINVAL;

		goto out;

	}



	cd->major = major;

	cd->baseminor = baseminor;

	cd->minorct = minorct;

fs/proc/devices.c

+4 −4
Original line number Diff line number Diff line
@@ -7,14 +7,14 @@ static int devinfo_show(struct seq_file *f, void *v) 
{

	int i = *(loff_t *) v;



	if (i < CHRDEV_MAJOR_HASH_SIZE) {

	if (i < CHRDEV_MAJOR_MAX) {

		if (i == 0)

			seq_puts(f, "Character devices:\n");

		chrdev_show(f, i);

	}

#ifdef CONFIG_BLOCK

	else {

		i -= CHRDEV_MAJOR_HASH_SIZE;

		i -= CHRDEV_MAJOR_MAX;

		if (i == 0)

			seq_puts(f, "\nBlock devices:\n");

		blkdev_show(f, i);
@@ -25,7 +25,7 @@ static int devinfo_show(struct seq_file *f, void *v) 


static void *devinfo_start(struct seq_file *f, loff_t *pos)

{

	if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))

	if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_MAX))

		return pos;

	return NULL;

}
@@ -33,7 +33,7 @@ static void *devinfo_start(struct seq_file *f, loff_t *pos) 
static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)

{

	(*pos)++;

	if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))

	if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_MAX))

		return NULL;

	return pos;

}

include/linux/fs.h

+1 −1
Original line number Diff line number Diff line
@@ -2470,7 +2470,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev, 
#endif



/* fs/char_dev.c */

#define CHRDEV_MAJOR_HASH_SIZE	255

#define CHRDEV_MAJOR_MAX 512

/* Marks the bottom of the first segment of free char majors */

#define CHRDEV_MAJOR_DYN_END 234

/* Marks the top and bottom of the second segment of free char majors */

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