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dm ioctl: remove unnecessary check when using dm_get_mdptr() 

__hash_remove() removes hash_cell with _hash_lock locked, so acquiring
_hash_lock can guarantee no-NULL hc returned from dm_get_mdptr() must
have not been removed and hc->md must still be md.

__hash_remove() also acquires dm_hash_cells_mutex before setting mdptr
as NULL. So in dm_copy_name_and_uuid(), after acquiring
dm_hash_cells_mutex and ensuring returned hc is not NULL, the returned
hc must still be alive and hc->md must still be md.

Remove the unnecessary hc->md != md checks when using dm_get_mdptr()
with _hash_lock or dm_hash_cells_mutex acquired.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Hou Tao 2022-12-16 12:23:53 +08:00 committed by Mike Snitzer
parent 69868bebfe
commit a2f998a78a
1 changed files with 3 additions and 3 deletions
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6
drivers/md/dm-ioctl.c
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@ -789,7 +789,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src
down_read(&_hash_lock); down_read(&_hash_lock);
hc = dm_get_mdptr(md); hc = dm_get_mdptr(md);
if (!hc || hc->md != md) { if (!hc) {
DMERR("device has been removed from the dev hash table."); DMERR("device has been removed from the dev hash table.");
goto out; goto out;
} }
@ -1500,7 +1500,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
/* stage inactive table */ /* stage inactive table */
down_write(&_hash_lock); down_write(&_hash_lock);
hc = dm_get_mdptr(md); hc = dm_get_mdptr(md);
if (!hc || hc->md != md) { if (!hc) {
DMERR("device has been removed from the dev hash table."); DMERR("device has been removed from the dev hash table.");
up_write(&_hash_lock); up_write(&_hash_lock);
r = -ENXIO; r = -ENXIO;
@ -2152,7 +2152,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
mutex_lock(&dm_hash_cells_mutex); mutex_lock(&dm_hash_cells_mutex);
hc = dm_get_mdptr(md); hc = dm_get_mdptr(md);
if (!hc || hc->md != md) { if (!hc) {
r = -ENXIO; r = -ENXIO;
goto out; goto out;
} }