Re: [PATCH v2 1/8] block: introduce blk_ksm_is_empty()

[Eric Biggers]

On Thu, Mar 25, 2021 at 09:26:02PM +, Satya Tangirala wrote:
> This function checks if a given keyslot manager supports any encryption
> mode/data unit size combination (and returns true if there is no such
> supported combination). Helps clean up code a little.
> 
> Signed-off-by: Satya Tangirala 
> ---
>  block/keyslot-manager.c | 13 +
>  drivers/md/dm-table.c   | 11 +--
>  include/linux/keyslot-manager.h |  2 ++
>  3 files changed, 16 insertions(+), 10 deletions(-)
> 
> diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
> index 2c4a55bea6ca..2a2b1a9785d2 100644
> --- a/block/keyslot-manager.c
> +++ b/block/keyslot-manager.c
> @@ -437,6 +437,19 @@ void blk_ksm_destroy(struct blk_keyslot_manager *ksm)
>  }
>  EXPORT_SYMBOL_GPL(blk_ksm_destroy);
>  
> +bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm)
> +{

I agree with Christoph that this could use a kerneldoc comment.

> diff --git a/include/linux/keyslot-manager.h b/include/linux/keyslot-manager.h
> index a27605e2f826..5bf0cea20c81 100644
> --- a/include/linux/keyslot-manager.h
> +++ b/include/linux/keyslot-manager.h
> @@ -117,4 +117,6 @@ bool blk_ksm_is_superset(struct blk_keyslot_manager 
> *ksm_superset,
>  void blk_ksm_update_capabilities(struct blk_keyslot_manager *target_ksm,
>struct blk_keyslot_manager *reference_ksm);
>  
> +bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm);
> +

It's easier to read if declarations are kept in the same order as the
definitions.

- Eric

Re: [PATCH v2 1/8] block: introduce blk_ksm_is_empty()

[Christoph Hellwig]

On Thu, Mar 25, 2021 at 09:26:02PM +, Satya Tangirala wrote:
> This function checks if a given keyslot manager supports any encryption
> mode/data unit size combination (and returns true if there is no such
> supported combination). Helps clean up code a little.

The name sounds a little strange to me, but the functionality looks
ok.  A kerneldoc comment might be useful to describe what it does so
that we don't have to rely on the name alone.

[PATCH v2 1/8] block: introduce blk_ksm_is_empty()

[Satya Tangirala]

This function checks if a given keyslot manager supports any encryption
mode/data unit size combination (and returns true if there is no such
supported combination). Helps clean up code a little.

Signed-off-by: Satya Tangirala 
---
 block/keyslot-manager.c | 13 +
 drivers/md/dm-table.c   | 11 +--
 include/linux/keyslot-manager.h |  2 ++
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
index 2c4a55bea6ca..2a2b1a9785d2 100644
--- a/block/keyslot-manager.c
+++ b/block/keyslot-manager.c
@@ -437,6 +437,19 @@ void blk_ksm_destroy(struct blk_keyslot_manager *ksm)
 }
 EXPORT_SYMBOL_GPL(blk_ksm_destroy);
 
+bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm)
+{
+   int i;
+
+   for (i = 0; i < ARRAY_SIZE(ksm->crypto_modes_supported); i++) {
+   if (ksm->crypto_modes_supported[i])
+   return false;
+   }
+
+   return true;
+}
+EXPORT_SYMBOL_GPL(blk_ksm_is_empty);
+
 bool blk_ksm_register(struct blk_keyslot_manager *ksm, struct request_queue *q)
 {
if (blk_integrity_queue_supports_integrity(q)) {
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 95391f78b8d5..db18a58adad7 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1313,7 +1313,6 @@ static int dm_table_construct_keyslot_manager(struct 
dm_table *t)
struct blk_keyslot_manager *ksm;
struct dm_target *ti;
unsigned int i;
-   bool ksm_is_empty = true;
 
dksm = kmalloc(sizeof(*dksm), GFP_KERNEL);
if (!dksm)
@@ -1350,15 +1349,7 @@ static int dm_table_construct_keyslot_manager(struct 
dm_table *t)
 * If the new KSM doesn't actually support any crypto modes, we may as
 * well represent it with a NULL ksm.
 */
-   ksm_is_empty = true;
-   for (i = 0; i < ARRAY_SIZE(ksm->crypto_modes_supported); i++) {
-   if (ksm->crypto_modes_supported[i]) {
-   ksm_is_empty = false;
-   break;
-   }
-   }
-
-   if (ksm_is_empty) {
+   if (blk_ksm_is_empty(ksm)) {
dm_destroy_keyslot_manager(ksm);
ksm = NULL;
}
diff --git a/include/linux/keyslot-manager.h b/include/linux/keyslot-manager.h
index a27605e2f826..5bf0cea20c81 100644
--- a/include/linux/keyslot-manager.h
+++ b/include/linux/keyslot-manager.h
@@ -117,4 +117,6 @@ bool blk_ksm_is_superset(struct blk_keyslot_manager 
*ksm_superset,
 void blk_ksm_update_capabilities(struct blk_keyslot_manager *target_ksm,
 struct blk_keyslot_manager *reference_ksm);
 
+bool blk_ksm_is_empty(struct blk_keyslot_manager *ksm);
+
 #endif /* __LINUX_KEYSLOT_MANAGER_H */
-- 
2.31.0.291.g576ba9dcdaf-goog