linux-kernel - Re: [PATCH 1/2] test_firmware: add suspend support to test buggy drivers

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Message-ID: <3ef0de52-5d17-c950-942f-29932df54880@tuxforce.de>
Date:   Thu, 22 Apr 2021 00:23:08 +0200
From:   Lukas Middendorf <kernel@...force.de>
To:     Luis Chamberlain <mcgrof@...nel.org>, rafael@...nel.org,
        gregkh@...uxfoundation.org, viro@...iv.linux.org.uk, jack@...e.cz,
        bvanassche@....org, jeyu@...nel.org, ebiederm@...ssion.com
Cc:     mchehab@...nel.org, keescook@...omium.org,
        linux-fsdevel@...r.kernel.org, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Lukas Middendorf <kernel@...force.de>
Subject: Re: [PATCH 1/2] test_firmware: add suspend support to test buggy
 drivers


On 17/04/2021 01:58, Luis Chamberlain wrote:
> Lukas Middendorf reported a situation where a driver's
> request_firmware() call on resume caused a stall. Upon
> inspection the issue was that the driver in question was
> calling request_firmware() only on resume, and since we
> currently do not have a generic kernel VFS freeze / thaw
> solution in place we are allowing races for filesystems
> to race against the disappearance of a block device, and
> this is presently an issue which can lead to a stall.
> 
> It is difficult to reproduce this unless you have hardware
> which mimics this setup. So to test this setup, let's just
> implement support for doing these wacky things. This lets
> us test that corner case easily as follows.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>

The resume test functionality added to test_firmware works as intended 
in reproducing the stall bug I reported.

However, the fw_test_resume.sh seems to be incomplete.

> +usage()
> +{
> +	echo "Usage: $0 [ -v ] | [ -h | --help]"
> +	echo ""
> +	echo "    --check-resume-test   Verify resume test"
> +	echo "    -h|--help             Help"
> +	echo
> +	echo "Without any arguments this will enable the resume firmware test"
> +	echo "after suspend. To verify that the test went well, run with -v".
> +	echo
> +	exit 1
> +}

The "-v" is not implemented as an alias to "--check-resume-test"

> +
> +verify_resume_test()
> +{
> +	trap "test_finish" EXIT
> +}

Does not seem to do anything regarding checking, just some cleanup.

> +
> +parse_args()
> +{
> +	if [ $# -eq 0 ]; then
> +		config_enable_resume_test
> +	else
> +		if [[ "$1" = "--check-resume-test" ]]; then
> +			config_disable_resume_test
> +			verify_resume_test
> +		else
> +			usage
> +		fi
> +	fi
> +}
> +

there should likely be a call

parse_args "$@"

> +exit 0