linux-kernel - Re: [PATCH -next v3 1/3] selftests/memory-hotplug: Add checking after online or offline

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Date:   Tue, 27 Sep 2022 01:36:18 +0000
From:   zhaogongyi <zhaogongyi@...wei.com>
To:     David Hildenbrand <david@...hat.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>
CC:     "akinobu.mita@...il.com" <akinobu.mita@...il.com>,
        "corbet@....net" <corbet@....net>,
        "osalvador@...e.de" <osalvador@...e.de>,
        "shuah@...nel.org" <shuah@...nel.org>
Subject: Re: [PATCH -next v3 1/3] selftests/memory-hotplug: Add checking after
 online or offline


> 
> On 26.09.22 15:03, Zhao Gongyi wrote:
> > Add checking for online_memory_expect_success()/
> > offline_memory_expect_success()/offline_memory_expect_fail(), or
> the
> > test would exit 0 although the functions return 1.
> >
> > Signed-off-by: Zhao Gongyi <zhaogongyi@...wei.com>
> > ---
> >   .../selftests/memory-hotplug/mem-on-off-test.sh   | 15
> ++++++++++++---
> >   1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/testing/selftests/memory-hotplug/mem-on-off-test.sh
> > b/tools/testing/selftests/memory-hotplug/mem-on-off-test.sh
> > index 46a97f318f58..3edda1f13f7b 100755
> > --- a/tools/testing/selftests/memory-hotplug/mem-on-off-test.sh
> > +++ b/tools/testing/selftests/memory-hotplug/mem-on-off-test.sh
> > @@ -266,7 +266,10 @@ done
> >   #
> >   echo $error >
> $NOTIFIER_ERR_INJECT_DIR/actions/MEM_GOING_ONLINE/error
> >   for memory in `hotpluggable_offline_memory`; do
> > -	online_memory_expect_fail $memory
> > +	online_memory_expect_fail $memory || {
> > +		echo "online memory $memory: unexpected success"
> 
> The functions themself already print an error, isn't it sufficient to set
> retval=1?

Indeed, this function is only called once. It is no need to add the log info.


> 
> > +		retval=1
> > +	}
> >   done
> >
> >   #
> > @@ -274,7 +277,10 @@ done
> >   #
> >   echo 0 >
> $NOTIFIER_ERR_INJECT_DIR/actions/MEM_GOING_ONLINE/error
> >   for memory in `hotpluggable_offline_memory`; do
> > -	online_memory_expect_success $memory
> > +	online_memory_expect_success $memory || {
> > +		echo "online memory $memory: unexpected fail"
> > +		retval=1
> > +	}
> >   done
> >
> >   #
> > @@ -283,7 +289,10 @@ done
> >   echo $error >
> $NOTIFIER_ERR_INJECT_DIR/actions/MEM_GOING_OFFLINE/error
> >   for memory in `hotpluggable_online_memory`; do
> >   	if [ $((RANDOM % 100)) -lt $ratio ]; then
> > -		offline_memory_expect_fail $memory
> > +		offline_memory_expect_fail $memory || {
> > +			echo "offline memory $memory: unexpected success"
> > +			retval=1
> > +		}
> 
> These functions return 0 if the result is as expected and 1 if the result is
> unexpected.
> 
> ... but wouldn't we evaluate the right hand side only if the result is "0" --
> expected? I might be wrong.
> 

Yes, if offline_memory_expect_fail's return value is not zero, then it will set 'retval=1'

> 
> Wouldn't it be simpler do it as in "Online all hot-pluggable memory again"
> 
> if ! online_memory_expect_success $memory; then
> 	retval=1
> fi
> 
> (similarly adjusting the function name)

I will send a new version of the patch to fix it.

Kind regards,
Gongyi