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

[Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

On Apr 21, 2020 / 02:35, Shinichiro Kawasaki wrote:
> On Mar 20, 2020 / 14:42, Omar Sandoval wrote:
> > 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"
> >
> 
> Hi Omar,
> 
> I noticed the commit cd11d001fe86 ("Support skipping tests from
> test{,_device}()") have side effects to some test cases. The unexpected run
> result "not run" is reported to test cases as follows:
> 
> - block/005 ... for non-rotational drives such as nullb
> - zbd/00[1-5]
> - zbd/007   ... for dm-linear device
> 
> Some helper functions _test_dev_is_rotational, _test_dev_is_partition or so
> are called within test_device() context, and left SKIP_REASON with values. It
> resulted in the "not run" result.
> 
> To fix this, I can think of two approaches. One is to unset SKIP_REASON after
> calling _test_dev_is_X helper functions within the test cases affected. This fix
> is straight forward but it will require similar care for future test case
> additions and changes. The other approach is to flag the test cases which judge
> skip during test run. For example, SKIP_DURING_RUN=1 can be defined in those
> test cases (block/030). The check script validates SKIP_REASON only if the test
> case is flagged. This second approach looks less costly for me.
> 
> Please let me know your thoughts about the fix approach. Thanks!

Now I found that Klaus Jensen already reported this and posted his fix patch.
My report was not necessary. Sorry about this noise.

-- 
Best Regards,
Shin'ichiro Kawasaki