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Commit da707c54 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by James Bottomley
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[SCSI] ch: fix device minor number management bug 



ch_probe uses the total number of ch devices as minor.

ch_probe:
	ch->minor = ch_devcount;
...
	ch_devcount++;

Then ch_remove decreases ch_devcount:

ch_remove:
	ch_devcount--;

If you have two ch devices, sch0 and sch1, and remove sch0,
ch_devcount is 1. Then if you add another ch device, ch_probe tries to
create sch1. So you get a warning and fail to create sch1:

Jan 24 16:01:05 nice kernel: sysfs: duplicate filename 'sch1' can not be created
Jan 24 16:01:05 nice kernel: WARNING: at fs/sysfs/dir.c:424 sysfs_add_one()
Jan 24 16:01:05 nice kernel: Pid: 2571, comm: iscsid Not tainted 2.6.24-rc7-ga3d2c2e8-dirty #1
Jan 24 16:01:05 nice kernel:
Jan 24 16:01:05 nice kernel: Call Trace:
Jan 24 16:01:05 nice kernel:  [<ffffffff802a22b8>] sysfs_add_one+0x54/0xbd
Jan 24 16:01:05 nice kernel:  [<ffffffff802a283c>] create_dir+0x4f/0x87
Jan 24 16:01:05 nice kernel:  [<ffffffff802a28a9>] sysfs_create_dir+0x35/0x4a
Jan 24 16:01:05 nice kernel:  [<ffffffff803069a1>] kobject_get+0x12/0x17
Jan 24 16:01:05 nice kernel:  [<ffffffff80306ece>] kobject_add+0xf3/0x1a6
Jan 24 16:01:05 nice kernel:  [<ffffffff8034252b>] class_device_add+0xaa/0x39d
Jan 24 16:01:05 nice kernel:  [<ffffffff803428fb>] class_device_create+0xcb/0xfa
Jan 24 16:01:05 nice kernel:  [<ffffffff80229e09>] printk+0x4e/0x56
Jan 24 16:01:05 nice kernel:  [<ffffffff802a2054>] sysfs_ilookup_test+0x0/0xf
Jan 24 16:01:05 nice kernel:  [<ffffffff88022580>] :ch:ch_probe+0xbe/0x61a

(snip)

This patch converts ch to use a standard minor number management way,
idr like sg and bsg.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent a3d2c2e8

drivers/scsi/ch.c

+40 −31
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <linux/compat.h>

#include <linux/chio.h>			/* here are all the ioctls */

#include <linux/mutex.h>

#include <linux/idr.h>



#include <scsi/scsi.h>

#include <scsi/scsi_cmnd.h>
@@ -33,6 +34,7 @@ 


#define CH_DT_MAX       16

#define CH_TYPES        8

#define CH_MAX_DEVS     128



MODULE_DESCRIPTION("device driver for scsi media changer devices");

MODULE_AUTHOR("Gerd Knorr <kraxel@bytesex.org>");
@@ -113,9 +115,8 @@ typedef struct { 
	struct mutex	    lock;

} scsi_changer;



static LIST_HEAD(ch_devlist);

static DEFINE_SPINLOCK(ch_devlist_lock);

static int ch_devcount;

static DEFINE_IDR(ch_index_idr);

static DEFINE_SPINLOCK(ch_index_lock);



static struct scsi_driver ch_template =

{
@@ -598,20 +599,17 @@ ch_release(struct inode *inode, struct file *file) 
static int

ch_open(struct inode *inode, struct file *file)

{

	scsi_changer *tmp, *ch;

	scsi_changer *ch;

	int minor = iminor(inode);



	spin_lock(&ch_devlist_lock);

	ch = NULL;

	list_for_each_entry(tmp,&ch_devlist,list) {

		if (tmp->minor == minor)

			ch = tmp;

	}

	spin_lock(&ch_index_lock);

	ch = idr_find(&ch_index_idr, minor);



	if (NULL == ch || scsi_device_get(ch->device)) {

		spin_unlock(&ch_devlist_lock);

		spin_unlock(&ch_index_lock);

		return -ENXIO;

	}

	spin_unlock(&ch_devlist_lock);

	spin_unlock(&ch_index_lock);



	file->private_data = ch;

	return 0;
@@ -914,6 +912,7 @@ static int ch_probe(struct device *dev) 
{

	struct scsi_device *sd = to_scsi_device(dev);

	struct class_device *class_dev;

	int minor, ret = -ENOMEM;

	scsi_changer *ch;



	if (sd->type != TYPE_MEDIUM_CHANGER)
@@ -923,7 +922,22 @@ static int ch_probe(struct device *dev) 
	if (NULL == ch)

		return -ENOMEM;



	ch->minor = ch_devcount;

	if (!idr_pre_get(&ch_index_idr, GFP_KERNEL))

		goto free_ch;



	spin_lock(&ch_index_lock);

	ret = idr_get_new(&ch_index_idr, ch, &minor);

	spin_unlock(&ch_index_lock);



	if (ret)

		goto free_ch;



	if (minor > CH_MAX_DEVS) {

		ret = -ENODEV;

		goto remove_idr;

	}



	ch->minor = minor;

	sprintf(ch->name,"ch%d",ch->minor);



	class_dev = class_device_create(ch_sysfs_class, NULL,
@@ -932,8 +946,8 @@ static int ch_probe(struct device *dev) 
	if (IS_ERR(class_dev)) {

		printk(KERN_WARNING "ch%d: class_device_create failed\n",

		       ch->minor);

		kfree(ch);

		return PTR_ERR(class_dev);

		ret = PTR_ERR(class_dev);

		goto remove_idr;

	}



	mutex_init(&ch->lock);
@@ -942,35 +956,29 @@ static int ch_probe(struct device *dev) 
	if (init)

		ch_init_elem(ch);



	dev_set_drvdata(dev, ch);

	sdev_printk(KERN_INFO, sd, "Attached scsi changer %s\n", ch->name);



	spin_lock(&ch_devlist_lock);

	list_add_tail(&ch->list,&ch_devlist);

	ch_devcount++;

	spin_unlock(&ch_devlist_lock);

	return 0;

remove_idr:

	idr_remove(&ch_index_idr, minor);

free_ch:

	kfree(ch);

	return ret;

}



static int ch_remove(struct device *dev)

{

	struct scsi_device *sd = to_scsi_device(dev);

	scsi_changer *tmp, *ch;

	scsi_changer *ch = dev_get_drvdata(dev);



	spin_lock(&ch_devlist_lock);

	ch = NULL;

	list_for_each_entry(tmp,&ch_devlist,list) {

		if (tmp->device == sd)

			ch = tmp;

	}

	BUG_ON(NULL == ch);

	list_del(&ch->list);

	spin_unlock(&ch_devlist_lock);

	spin_lock(&ch_index_lock);

	idr_remove(&ch_index_idr, ch->minor);

	spin_unlock(&ch_index_lock);



	class_device_destroy(ch_sysfs_class,

			     MKDEV(SCSI_CHANGER_MAJOR,ch->minor));

	kfree(ch->dt);

	kfree(ch);

	ch_devcount--;

	return 0;

}
@@ -1007,6 +1015,7 @@ static void __exit exit_ch_module(void) 
	scsi_unregister_driver(&ch_template.gendrv);

	unregister_chrdev(SCSI_CHANGER_MAJOR, "ch");

	class_destroy(ch_sysfs_class);

	idr_destroy(&ch_index_idr);

}



module_init(init_ch_module);