Re: [PATCH v3 09/10] ntb_test: Add a selftest script for the NTB subsystem

From: Logan Gunthorpe <logang@deltatee.com>
To: Allen Hubbe <Allen.Hubbe@emc.com>,
	"'Jon Mason'" <jdmason@kudzu.us>,
	"'Dave Jiang'" <dave.jiang@intel.com>
Cc: "'Shuah Khan'" <shuahkh@osg.samsung.com>,
	"'Sudip Mukherjee'" <sudipm.mukherjee@gmail.com>,
	"'Arnd Bergmann'" <arnd@arndb.de>,
	linux-kernel@vger.kernel.org, linux-ntb@googlegroups.com,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 09/10] ntb_test: Add a selftest script for the NTB subsystem
Date: Wed, 15 Jun 2016 15:54:01 -0600	[thread overview]
Message-ID: <5761CE79.8090703@deltatee.com> (raw)
In-Reply-To: <007901d1c74f$dcdab6c0$96902440$@emc.com>

On 15/06/16 03:49 PM, Allen Hubbe wrote:
>> +function link_test()
>> +{
>> +	LOC=$1
>> +	REM=$2
>> +	EXP=0
>> +
>> +	echo "Running link tests on: $(basename $LOC) / $(basename $REM)"
>> +
>> +	write_file "N" "$LOC/link"
>> +	write_file "N" "$LOC/link_event"
> 
> If it fails to bring down the link, won't it just block waiting on link_event and never make it to the next step of the test?
> 
>> +	if [[ $(read_file "$REM/link") != "N" ]]; then
>> +		echo "Expected remote link to be down in $REM/link" >&2
>> +		exit -1
>> +	fi
>> +
>> +	write_file "Y" "$LOC/link"
>> +	write_file "Y" "$LOC/link_event"
>> +
>> +	echo "  Passed"
>> +}

Well, the test is really intended to ensure both sides of the link see
changes to the link status. If the driver is somehow buggy and the link
never goes down/up when requested there's little I can do here except
block forever. Unless we want to add a timeout to the link_event file
(which I'd rather not).

You'd have the same issue if, when bringing the link up for the first
time, the link does not come back.

Logan