On Wed, Apr 09, 2025 at 10:58:04AM +0800, Herbert Xu wrote: > > What I'll do is make the crypto_unregister call wait for the users > to go away. That matches how the network device unregistration works > and hopefully should solve this problem. But keep your eyes for > dead locks that used to plague netdev unregistration :) That was a dumb idea. All it would do is make the shutdown hang. So here is a different tack. Let the algorithms stick around, by allocating them dynamically instead. Then we could simply kfree them when the user finally disappears (if ever). Note to make this work, caam needs to be modified to allocate the algorithms dynamically (kmemdup should work), and add a cra_destroy function to kfree the memory. ---8<--- The current algorithm unregistration mechanism originated from software crypto. The code relies on module reference counts to stop in-use algorithms from being unregistered. Therefore if the unregistration function is reached, it is assumed that the module reference count has hit zero and thus the algorithm reference count should be exactly 1. This is completely broken for hardware devices, which can be unplugged at random. Fix this by allowing algorithms to be destroyed later if a destroy callback is provided. Reported-by: Sean Anderson <sean.anderson@xxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> diff --git a/crypto/algapi.c b/crypto/algapi.c index 5b8a4c787387..f368c0dc0d6d 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -481,10 +481,10 @@ void crypto_unregister_alg(struct crypto_alg *alg) if (WARN(ret, "Algorithm %s is not registered", alg->cra_driver_name)) return; - if (WARN_ON(refcount_read(&alg->cra_refcnt) != 1)) - return; - - if (alg->cra_type && alg->cra_type->destroy) + if (alg->cra_destroy) + crypto_alg_put(alg); + else if (!WARN_ON(refcount_read(&alg->cra_refcnt) != 1) && + alg->cra_type && alg->cra_type->destroy) alg->cra_type->destroy(alg); crypto_remove_final(&list); -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
