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Commit 6cb4f4df authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: cdc-acm: use idr to manage minor numbers 



Use the idr-interface rather than a static table to manage minor-number
allocations.

This allows us to easily switch over to fully dynamic minor allocations
when the TTY-layer can handle that.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Acked-by: default avatarOliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 83ed07c5

drivers/usb/class/cdc-acm.c

+17 −21
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ 
#include <linux/usb/cdc.h>

#include <asm/byteorder.h>

#include <asm/unaligned.h>

#include <linux/idr.h>

#include <linux/list.h>



#include "cdc-acm.h"
@@ -56,27 +57,27 @@ 


static struct usb_driver acm_driver;

static struct tty_driver *acm_tty_driver;

static struct acm *acm_table[ACM_TTY_MINORS];



static DEFINE_MUTEX(acm_table_lock);

static DEFINE_IDR(acm_minors);

static DEFINE_MUTEX(acm_minors_lock);



static void acm_tty_set_termios(struct tty_struct *tty,

				struct ktermios *termios_old);



/*

 * acm_table accessors

 * acm_minors accessors

 */



/*

 * Look up an ACM structure by index. If found and not disconnected, increment

 * Look up an ACM structure by minor. If found and not disconnected, increment

 * its refcount and return it with its mutex held.

 */

static struct acm *acm_get_by_index(unsigned index)

static struct acm *acm_get_by_minor(unsigned int minor)

{

	struct acm *acm;



	mutex_lock(&acm_table_lock);

	acm = acm_table[index];

	mutex_lock(&acm_minors_lock);

	acm = idr_find(&acm_minors, minor);

	if (acm) {

		mutex_lock(&acm->mutex);

		if (acm->disconnected) {
@@ -87,7 +88,7 @@ static struct acm *acm_get_by_index(unsigned index) 
			mutex_unlock(&acm->mutex);

		}

	}

	mutex_unlock(&acm_table_lock);

	mutex_unlock(&acm_minors_lock);

	return acm;

}
@@ -98,14 +99,9 @@ static int acm_alloc_minor(struct acm *acm) 
{

	int minor;



	mutex_lock(&acm_table_lock);

	for (minor = 0; minor < ACM_TTY_MINORS; minor++) {

		if (!acm_table[minor]) {

			acm_table[minor] = acm;

			break;

		}

	}

	mutex_unlock(&acm_table_lock);

	mutex_lock(&acm_minors_lock);

	minor = idr_alloc(&acm_minors, acm, 0, ACM_TTY_MINORS, GFP_KERNEL);

	mutex_unlock(&acm_minors_lock);



	return minor;

}
@@ -113,9 +109,9 @@ static int acm_alloc_minor(struct acm *acm) 
/* Release the minor number associated with 'acm'.  */

static void acm_release_minor(struct acm *acm)

{

	mutex_lock(&acm_table_lock);

	acm_table[acm->minor] = NULL;

	mutex_unlock(&acm_table_lock);

	mutex_lock(&acm_minors_lock);

	idr_remove(&acm_minors, acm->minor);

	mutex_unlock(&acm_minors_lock);

}



/*
@@ -497,7 +493,7 @@ static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) 


	dev_dbg(tty->dev, "%s\n", __func__);



	acm = acm_get_by_index(tty->index);

	acm = acm_get_by_minor(tty->index);

	if (!acm)

		return -ENODEV;
@@ -1316,7 +1312,7 @@ static int acm_probe(struct usb_interface *intf, 
		goto alloc_fail;



	minor = acm_alloc_minor(acm);

	if (minor == ACM_TTY_MINORS) {

	if (minor < 0) {

		dev_err(&intf->dev, "no more free acm devices\n");

		kfree(acm);

		return -ENODEV;