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Revert "dm: fix a race condition in retrieve_deps"

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This reverts commit f6007dce0c.

Commit f6007dce0c ("dm: fix a race condition in retrieve_deps") was
added to fix a race between retrieving the list of dm table devices and
multipath_message() modifying the list of table devices. But Commit
a48f6b82c5 ("dm mpath: don't call dm_get_device in multipath_message")
removed the call to dm_get_device() from multipath_message(). After that
commit, the only calls to dm_get_device() and dm_put_device() are in
target constructors and destructors, so the race with retrieve_deps() is
no longer possible.

Suggested-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Benjamin Marzinski 2026-01-27 19:12:23 -05:00 • committed by Mikulas Patocka
parent 787bd63ee6
commit 4550a71b17
3 changed files with 9 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

1
drivers/md/dm-core.h
View file

@ -215,7 +215,6 @@ struct dm_table {
/* a list of devices used by this table */
struct list_head devices;
struct rw_semaphore devices_lock;
/* events get handed up using this callback */
void (*event_fn)(void *data);

7
drivers/md/dm-ioctl.c
View file

@ -1648,8 +1648,6 @@ static void retrieve_deps(struct dm_table *table,
struct dm_dev_internal *dd;
struct dm_target_deps *deps;
down_read(&table->devices_lock);
deps = get_result_buffer(param, param_size, &len);
/*
@ -1664,7 +1662,7 @@ static void retrieve_deps(struct dm_table *table,
needed = struct_size(deps, dev, count);
if (len < needed) {
param->flags |= DM_BUFFER_FULL_FLAG;
goto out;
return;
}
/*
@ -1676,9 +1674,6 @@ static void retrieve_deps(struct dm_table *table,
deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);
param->data_size = param->data_start + needed;
out:
up_read(&table->devices_lock);
}
static int table_deps(struct file *filp, struct dm_ioctl *param, size_t param_size)

32
drivers/md/dm-table.c
View file

@ -139,7 +139,6 @@ int dm_table_create(struct dm_table **result, blk_mode_t mode,
return -ENOMEM;
INIT_LIST_HEAD(&t->devices);
init_rwsem(&t->devices_lock);
if (!num_targets)
num_targets = KEYS_PER_NODE;
@ -380,20 +379,16 @@ int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
if (dev == disk_devt(t->md->disk))
return -EINVAL;
down_write(&t->devices_lock);
dd = find_device(&t->devices, dev);
if (!dd) {
dd = kmalloc(sizeof(*dd), GFP_KERNEL);
if (!dd) {
r = -ENOMEM;
goto unlock_ret_r;
}
if (!dd)
return -ENOMEM;
r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev);
if (r) {
kfree(dd);
goto unlock_ret_r;
return r;
}
refcount_set(&dd->count, 1);
@ -403,17 +398,12 @@ int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
goto unlock_ret_r;
return r;
}
refcount_inc(&dd->count);
out:
up_write(&t->devices_lock);
*result = dd->dm_dev;
return 0;
unlock_ret_r:
up_write(&t->devices_lock);
return r;
}
EXPORT_SYMBOL(dm_get_device);
@ -464,12 +454,9 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
void dm_put_device(struct dm_target *ti, struct dm_dev *d)
{
int found = 0;
struct dm_table *t = ti->table;
struct list_head *devices = &t->devices;
struct list_head *devices = &ti->table->devices;
struct dm_dev_internal *dd;
down_write(&t->devices_lock);
list_for_each_entry(dd, devices, list) {
if (dd->dm_dev == d) {
found = 1;
@ -478,17 +465,14 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
}
if (!found) {
DMERR("%s: device %s not in table devices list",
dm_device_name(t->md), d->name);
goto unlock_ret;
dm_device_name(ti->table->md), d->name);
return;
}
if (refcount_dec_and_test(&dd->count)) {
dm_put_table_device(t->md, d);
dm_put_table_device(ti->table->md, d);
list_del(&dd->list);
kfree(dd);
}
unlock_ret:
up_write(&t->devices_lock);
}
EXPORT_SYMBOL(dm_put_device);