Commit 02244ba4 authored by Herbert Xu's avatar Herbert Xu
Browse files

crypto: api - Add more comments to crypto_remove_spawns 



This patch explains the logic behind crypto_remove_spawns and its
underling crypto_more_spawns.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 4f87ee11

crypto/algapi.c

+25 −0
Original line number Original line Diff line number Diff line
@@ -82,6 +82,15 @@ static void crypto_destroy_instance(struct crypto_alg *alg) 
	crypto_tmpl_put(tmpl);

	crypto_tmpl_put(tmpl);

}

}





/*

 * This function adds a spawn to the list secondary_spawns which

 * will be used at the end of crypto_remove_spawns to unregister

 * instances, unless the spawn happens to be one that is depended

 * on by the new algorithm (nalg in crypto_remove_spawns).

 *

 * This function is also responsible for resurrecting any algorithms

 * in the dependency chain of nalg by unsetting n->dead.

 */

static struct list_head *crypto_more_spawns(struct crypto_alg *alg,

static struct list_head *crypto_more_spawns(struct crypto_alg *alg,

					    struct list_head *stack,

					    struct list_head *stack,

					    struct list_head *top,

					    struct list_head *top,
@@ -128,6 +137,12 @@ static void crypto_remove_instance(struct crypto_instance *inst, 
	BUG_ON(!list_empty(&inst->alg.cra_users));

	BUG_ON(!list_empty(&inst->alg.cra_users));

}

}





/*

 * Given an algorithm alg, remove all algorithms that depend on it

 * through spawns.  If nalg is not null, then exempt any algorithms

 * that is depended on by nalg.  This is useful when nalg itself

 * depends on alg.

 */

void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list,

void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list,

			  struct crypto_alg *nalg)

			  struct crypto_alg *nalg)

{

{
@@ -146,6 +161,11 @@ void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list, 
		list_move(&spawn->list, &top);

		list_move(&spawn->list, &top);

	}

	}





	/*

	 * Perform a depth-first walk starting from alg through

	 * the cra_users tree.  The list stack records the path

	 * from alg to the current spawn.

	 */

	spawns = &top;

	spawns = &top;

	do {

	do {

		while (!list_empty(spawns)) {

		while (!list_empty(spawns)) {
@@ -180,6 +200,11 @@ void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list, 
	} while ((spawns = crypto_more_spawns(alg, &stack, &top,

	} while ((spawns = crypto_more_spawns(alg, &stack, &top,

					      &secondary_spawns)));

					      &secondary_spawns)));





	/*

	 * Remove all instances that are marked as dead.  Also

	 * complete the resurrection of the others by moving them

	 * back to the cra_users list.

	 */

	list_for_each_entry_safe(spawn, n, &secondary_spawns, list) {

	list_for_each_entry_safe(spawn, n, &secondary_spawns, list) {

		if (!spawn->dead)

		if (!spawn->dead)

			list_move(&spawn->list, &spawn->alg->cra_users);

			list_move(&spawn->list, &spawn->alg->cra_users);