From: Hannes Reinecke <hare@suse.de>
Date: Mon, 20 Apr 2015 11:37:35 +0200
Subject: [PATCH] ch: fixup refcounting imbalance for SCSI devices
References: bsc#1124235
Patch-Mainline: submitted linux-scsi 2020/02/13
The SCSI device is required to be present during ch_probe()
and ch_open(). But the SCSI device itself is only checked during
ch_open(), so it's anyones guess if it had been present during
ch_probe(). And consequently we can't reliably detach it during
ch_release(), as ch_remove() might have been called first.
So initialize the changer device during ch_probe(), and
take a reference to the SCSI device during both ch_probe()
and ch_open().
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
---
drivers/scsi/ch.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/drivers/scsi/ch.c b/drivers/scsi/ch.c
index ed5f4a6ae270..974afb4bd5fe 100644
--- a/drivers/scsi/ch.c
+++ b/drivers/scsi/ch.c
@@ -569,6 +569,7 @@ static void ch_destroy(struct kref *ref)
{
scsi_changer *ch = container_of(ref, scsi_changer, ref);
+ ch->device = NULL;
kfree(ch->dt);
kfree(ch);
}
@@ -594,14 +595,17 @@ ch_open(struct inode *inode, struct file *file)
spin_lock(&ch_index_lock);
ch = idr_find(&ch_index_idr, minor);
- if (NULL == ch || scsi_device_get(ch->device)) {
+ if (NULL == ch || !kref_get_unless_zero(&ch->ref)) {
spin_unlock(&ch_index_lock);
mutex_unlock(&ch_mutex);
return -ENXIO;
}
- kref_get(&ch->ref);
spin_unlock(&ch_index_lock);
-
+ if (scsi_device_get(ch->device)) {
+ kref_put(&ch->ref, ch_destroy);
+ mutex_unlock(&ch_mutex);
+ return -ENXIO;
+ }
file->private_data = ch;
mutex_unlock(&ch_mutex);
return 0;
@@ -938,6 +942,12 @@ static int ch_probe(struct device *dev)
ch->minor = ret;
sprintf(ch->name,"ch%d",ch->minor);
+ ret = scsi_device_get(sd);
+ if (ret) {
+ sdev_printk(KERN_WARNING, sd, "ch%d: failed to get device\n",
+ ch->minor);
+ goto remove_idr;
+ }
class_dev = device_create(ch_sysfs_class, dev,
MKDEV(SCSI_CHANGER_MAJOR, ch->minor), ch,
@@ -946,7 +956,7 @@ static int ch_probe(struct device *dev)
sdev_printk(KERN_WARNING, sd, "ch%d: device_create failed\n",
ch->minor);
ret = PTR_ERR(class_dev);
- goto remove_idr;
+ goto put_device;
}
mutex_init(&ch->lock);
@@ -964,6 +974,8 @@ static int ch_probe(struct device *dev)
return 0;
destroy_dev:
device_destroy(ch_sysfs_class, MKDEV(SCSI_CHANGER_MAJOR, ch->minor));
+put_device:
+ scsi_device_put(sd);
remove_idr:
idr_remove(&ch_index_idr, ch->minor);
free_ch:
@@ -977,9 +989,11 @@ static int ch_remove(struct device *dev)
spin_lock(&ch_index_lock);
idr_remove(&ch_index_idr, ch->minor);
+ dev_set_drvdata(dev, NULL);
spin_unlock(&ch_index_lock);
device_destroy(ch_sysfs_class, MKDEV(SCSI_CHANGER_MAJOR,ch->minor));
+ scsi_device_put(ch->device);
kref_put(&ch->ref, ch_destroy);
return 0;
}
--
2.16.4