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Date:   Tue, 28 Sep 2021 11:32:09 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Vladis Dronov <vdronov@redhat.com>,
        Simo Sorce <ssorce@redhat.com>,
        Eric Biggers <ebiggers@kernel.org>, llvm@lists.linux.dev
Subject: Re: [v2 PATCH] crypto: api - Fix built-in testing dependency failures
Message-ID: <YVNfqUVJ7w4Z3WXK@archlinux-ax161>
References: <20210913071251.GA15235@gondor.apana.org.au>
 <20210917002619.GA6407@gondor.apana.org.au>
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On Fri, Sep 17, 2021 at 08:26:19AM +0800, Herbert Xu wrote:
> When complex algorithms that depend on other algorithms are built
> into the kernel, the order of registration must be done such that
> the underlying algorithms are ready before the ones on top are
> registered.  As otherwise they would fail during the self-test
> which is required during registration.
> 
> In the past we have used subsystem initialisation ordering to
> guarantee this.  The number of such precedence levels are limited
> and they may cause ripple effects in other subsystems.
> 
> This patch solves this problem by delaying all self-tests during
> boot-up for built-in algorithms.  They will be tested either when
> something else in the kernel requests for them, or when we have
> finished registering all built-in algorithms, whichever comes
> earlier.
> 
> Reported-by: Vladis Dronov <vdronov@redhat.com>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch as commit 3cefb01905df ("crypto: api - Fix built-in testing
dependency failures") in -next (along with the follow up fix) causes the
following depmod error:

$ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc-linux- INSTALL_MOD_PATH=rootfs ppc44x_defconfig all modules_install
depmod: ERROR: Cycle detected: crypto -> crypto_algapi -> crypto
depmod: ERROR: Found 2 modules in dependency cycles!
make: *** [Makefile:1946: modules_install] Error 1

Initially reported on our CI:

https://github.com/ClangBuiltLinux/continuous-integration2/runs/3732847295?check_suite_focus=true

Cheers,
Nathan