Re: [PATCH blktests v2 4/4] Add a test that triggers the blk_mq_realloc_hw_ctxs() error path

[Omar Sandoval <osandov@osandov.com>]

On Sun, Mar 15, 2020 at 03:13:20PM -0700, Bart Van Assche wrote:
> Add a test that triggers the code touched by commit d0930bb8f46b ("blk-mq:
> Fix a recently introduced regression in blk_mq_realloc_hw_ctxs()"). This
> test only runs if a recently added fault injection feature is available,
> namely commit 596444e75705 ("null_blk: Add support for init_hctx() fault
> injection").
> 
> Cc: Ming Lei <ming.lei@redhat.com>
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  tests/block/030     | 42 ++++++++++++++++++++++++++++++++++++++++++
>  tests/block/030.out |  1 +
>  2 files changed, 43 insertions(+)
>  create mode 100755 tests/block/030
>  create mode 100644 tests/block/030.out
> 
> diff --git a/tests/block/030 b/tests/block/030
> new file mode 100755
> index 000000000000..861c85c27f09
> --- /dev/null
> +++ b/tests/block/030
> @@ -0,0 +1,42 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright 2020 Google LLC
> +#
> +# Trigger the blk_mq_realloc_hw_ctxs() error path.
> +
> +. tests/block/rc
> +. common/null_blk
> +
> +DESCRIPTION="trigger the blk_mq_realloc_hw_ctxs() error path"
> +QUICK=1
> +
> +requires() {
> +	_have_null_blk || return $?
> +	_have_module_param null_blk init_hctx || return $?
> +}
> +
> +test() {
> +	local i sq=/sys/kernel/config/nullb/nullb0/submit_queues
> +
> +	: "${TIMEOUT:=30}"
> +	if ! _init_null_blk nr_devices=0 queue_mode=2 "init_hctx=$(nproc),100,0,0"; then
> +		echo "Loading null_blk failed"
> +		return 1
> +	fi
> +	if ! _configure_null_blk nullb0 completion_nsec=0 blocksize=512 size=16\
> +	     submit_queues="$(nproc)" memory_backed=1 power=1; then
> +		echo "Configuring null_blk failed"
> +		return 1
> +	fi
> +	if { echo "$(<"$sq")" >$sq; } 2>/dev/null; then
> +		for ((i=0;i<100;i++)); do
> +			echo 1 >$sq
> +			nproc >$sq
> +		done
> +	else
> +		echo "Skipping test because $sq cannot be modified" >>"$FULL"

I just pushed the support for allowing skipping from the middle of a
test, so now you could make this

	SKIP_REASON="Skipping test because $sq cannot be modified"

> +	fi
> +	rmdir /sys/kernel/config/nullb/nullb0
> +	_exit_null_blk
> +	echo Passed
> +}
> diff --git a/tests/block/030.out b/tests/block/030.out
> new file mode 100644
> index 000000000000..863339fb8ced
> --- /dev/null
> +++ b/tests/block/030.out
> @@ -0,0 +1 @@
> +Passed