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Message-Id: <20080124171738L.fujita.tomonori@lab.ntt.co.jp>
Date: Thu, 24 Jan 2008 17:17:38 +0900
From: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To: James.Bottomley@...senPartnership.com
Cc: linux-kernel@...r.kernel.org, tomof@....org
Subject: [PATCH 1/2] 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, e.g. 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)
And you can't add new ch device any more.
This patch converts ch to use a common minor number management way,
idr like sg and bsg do.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
---
drivers/scsi/ch.c | 71 +++++++++++++++++++++++++++++-----------------------
1 files changed, 40 insertions(+), 31 deletions(-)
diff --git a/drivers/scsi/ch.c b/drivers/scsi/ch.c
index 765f2fc..2b07014 100644
--- a/drivers/scsi/ch.c
+++ b/drivers/scsi/ch.c
@@ -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@...esex.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);
--
1.5.3.4
--
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