[PATCH 4/4] Revert "scsi, block: fix duplicate bdi name registration crashes"

Jan Kara
2017-03-09T10:16:24Z

This reverts commit 0dba1314d4f81115dce711292ec7981d17231064. It causes
leaking of device numbers for SCSI when SCSI registers multiple gendisks
for one request_queue in succession. It can be easily reproduced using
Omar's script [1] on kernel with CONFIG_DEBUG_TEST_DRIVER_REMOVE.
Furthermore the protection provided by this commit is not needed anymore
as the problem it was fixing got also fixed by commit 165a5e22fafb
"block: Move bdi_unregister() to del_gendisk()".

[1]: http://marc.info/?l=linux-block&m=148554717109098&w=2

Tested-by: Omar Sandoval <osandov@fb.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
block/blk-core.c | 2 --
block/genhd.c | 21 ---------------------
drivers/scsi/sd.c | 41 ++++++++---------------------------------
include/linux/blkdev.h | 1 -
include/linux/genhd.h | 8 --------
5 files changed, 8 insertions(+), 65 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1086dac8724c..a76895c9776d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -578,8 +578,6 @@ void blk_cleanup_queue(struct request_queue *q)
q->queue_lock = &q->__queue_lock;
spin_unlock_irq(lock);

- put_disk_devt(q->disk_devt);
-
/* @q is and will stay empty, shutdown and put */
blk_put_queue(q);
}
diff --git a/block/genhd.c b/block/genhd.c
index 94f323842b52..a9c516a8b37d 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -572,20 +572,6 @@ static void register_disk(struct device *parent, struct gendisk *disk)
disk_part_iter_exit(&piter);
}

-void put_disk_devt(struct disk_devt *disk_devt)
-{
- if (disk_devt && atomic_dec_and_test(&disk_devt->count))
- disk_devt->release(disk_devt);
-}
-EXPORT_SYMBOL(put_disk_devt);
-
-void get_disk_devt(struct disk_devt *disk_devt)
-{
- if (disk_devt)
- atomic_inc(&disk_devt->count);
-}
-EXPORT_SYMBOL(get_disk_devt);
-
/**
* device_add_disk - add partitioning information to kernel list
* @parent: parent device for the disk
@@ -626,13 +612,6 @@ void device_add_disk(struct device *parent, struct gendisk *disk)

disk_alloc_events(disk);

- /*
- * Take a reference on the devt and assign it to queue since it
- * must not be reallocated while the bdi is registered
- */
- disk->queue->disk_devt = disk->disk_devt;
- get_disk_devt(disk->disk_devt);
-
/* Register BDI before referencing it from bdev */
bdi = disk->queue->backing_dev_info;
bdi_register_owner(bdi, disk_to_dev(disk));
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c7839f6c35cc..d277e8620e3e 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3075,23 +3075,6 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
put_device(&sdkp->dev);
}

-struct sd_devt {
- int idx;
- struct disk_devt disk_devt;
-};
-
-static void sd_devt_release(struct disk_devt *disk_devt)
-{
- struct sd_devt *sd_devt = container_of(disk_devt, struct sd_devt,
- disk_devt);
-
- spin_lock(&sd_index_lock);
- ida_remove(&sd_index_ida, sd_devt->idx);
- spin_unlock(&sd_index_lock);
-
- kfree(sd_devt);
-}
-
/**
* sd_probe - called during driver initialization and whenever a
* new scsi device is attached to the system. It is called once
@@ -3113,7 +3096,6 @@ static void sd_devt_release(struct disk_devt *disk_devt)
static int sd_probe(struct device *dev)
{
struct scsi_device *sdp = to_scsi_device(dev);
- struct sd_devt *sd_devt;
struct scsi_disk *sdkp;
struct gendisk *gd;
int index;
@@ -3139,13 +3121,9 @@ static int sd_probe(struct device *dev)
if (!sdkp)
goto out;

- sd_devt = kzalloc(sizeof(*sd_devt), GFP_KERNEL);
- if (!sd_devt)
- goto out_free;
-
gd = alloc_disk(SD_MINORS);
if (!gd)
- goto out_free_devt;
+ goto out_free;

do {
if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
@@ -3161,11 +3139,6 @@ static int sd_probe(struct device *dev)
goto out_put;
}

- atomic_set(&sd_devt->disk_devt.count, 1);
- sd_devt->disk_devt.release = sd_devt_release;
- sd_devt->idx = index;
- gd->disk_devt = &sd_devt->disk_devt;
-
error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
if (error) {
sdev_printk(KERN_WARNING, sdp, "SCSI disk (sd) name length exceeded.\n");
@@ -3205,12 +3178,11 @@ static int sd_probe(struct device *dev)
return 0;

out_free_index:
- put_disk_devt(&sd_devt->disk_devt);
- sd_devt = NULL;
+ spin_lock(&sd_index_lock);
+ ida_remove(&sd_index_ida, index);
+ spin_unlock(&sd_index_lock);
out_put:
put_disk(gd);
- out_free_devt:
- kfree(sd_devt);
out_free:
kfree(sdkp);
out:
@@ -3271,7 +3243,10 @@ static void scsi_disk_release(struct device *dev)
struct scsi_disk *sdkp = to_scsi_disk(dev);
struct gendisk *disk = sdkp->disk;

- put_disk_devt(disk->disk_devt);
+ spin_lock(&sd_index_lock);
+ ida_remove(&sd_index_ida, sdkp->index);
+ spin_unlock(&sd_index_lock);
+
disk->private_data = NULL;
put_disk(disk);
put_device(&sdkp->device->sdev_gendev);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 796016e63c1d..5a7da607ca04 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -435,7 +435,6 @@ struct request_queue {
struct delayed_work delay_work;

struct backing_dev_info *backing_dev_info;
- struct disk_devt *disk_devt;

/*
* The queue owner gets to use this for whatever they like.
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index a999d281a2f1..76f39754e7b0 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -167,13 +167,6 @@ struct blk_integrity {
};

#endif /* CONFIG_BLK_DEV_INTEGRITY */
-struct disk_devt {
- atomic_t count;
- void (*release)(struct disk_devt *disk_devt);
-};
-
-void put_disk_devt(struct disk_devt *disk_devt);
-void get_disk_devt(struct disk_devt *disk_devt);

struct gendisk {
/* major, first_minor and minors are input parameters only,
@@ -183,7 +176,6 @@ struct gendisk {
int first_minor;
int minors; /* maximum number of minors, =1 for
* disks that can't be partitioned. */
- struct disk_devt *disk_devt;

char disk_name[DISK_NAME_LEN]; /* name of major driver */
char *(*devnode)(struct gendisk *gd, umode_t *mode);
--
2.10.2