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Subject[PATCH] dm: remove unnecessary check when using dm_get_mdptr()
Date
From: Hou Tao <houtao1@huawei.com>

__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.

So removing these 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>
---
drivers/md/dm-ioctl.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 3bfc1583c20a..2a86524661d1 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -772,7 +772,7 @@ static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *src

down_read(&_hash_lock);
hc = dm_get_mdptr(md);
- if (!hc || hc->md != md) {
+ if (!hc) {
DMERR("device has been removed from the dev hash table.");
goto out;
}
@@ -1476,7 +1476,7 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si
/* stage inactive table */
down_write(&_hash_lock);
hc = dm_get_mdptr(md);
- if (!hc || hc->md != md) {
+ if (!hc) {
DMERR("device has been removed from the dev hash table.");
up_write(&_hash_lock);
r = -ENXIO;
@@ -2128,7 +2128,7 @@ int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)

mutex_lock(&dm_hash_cells_mutex);
hc = dm_get_mdptr(md);
- if (!hc || hc->md != md) {
+ if (!hc) {
r = -ENXIO;
goto out;
}
--
2.29.2
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