linux-kernel - Re: [PATCH v4 15/16] block: sed-opal: don't repeat opal

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Date:   Mon, 4 Feb 2019 23:44:16 +0100 (CET)
From:   David Kozub <zub@...ux.fjfi.cvut.cz>
To:     Christoph Hellwig <hch@...radead.org>
cc:     Jens Axboe <axboe@...nel.dk>,
        Jonathan Derrick <jonathan.derrick@...el.com>,
        Scott Bauer <sbauer@...donthack.me>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
Subject: Re: [PATCH v4 15/16] block: sed-opal: don't repeat opal_discovery0
 in each steps array

On Mon, 4 Feb 2019, Christoph Hellwig wrote:

>> +	/* first do a discovery0 */
>> +	error = opal_discovery0_step(dev);
>>
>> +	for (state = 0; !error && state < n_steps; state++)
>> +		error = execute_step(dev, &steps[state], state);
>> +
>> +	/*
>> +	 * For each OPAL command the first step in steps starts some sort of
>> +	 * session. If an error occurred in the initial discovery0 or if an
>> +	 * error occurred in the first step (and thus stopping the loop with
>> +	 * state == 1) then there was an error before or during the attempt to
>> +	 * start a session. Therefore we shouldn't attempt to terminate a
>> +	 * session, as one has not yet been created.
>> +	 */
>> +	if (error && state > 1)
>> +		end_opal_session_error(dev);
>>
>>  	return error;
>
> The flow here is a little too condensed for my taste.  Why not the
> plain obvoious, if a little longer:
>
> 	error = error = opal_discovery0_step(dev);
> 	if (error)
> 		return error;
>
> 	for (state = 0; state < n_steps; state++) {
> 		error = execute_step(dev, &steps[state], state);
> 		if (error)
> 			goto out_error;
> 	}
>
> 	return 0;
>
> out_error:
> 	if (state > 1)
> 		end_opal_session_error(dev);
> 	return error;

No problem, I can use this version. But I think there is a minor issue - 
the same one I hit in my original change, just from the other direction:

If the loop succeds for the 0-th element of steps, and then fails for the 
1st element, then state equals 1 yet the session has been started, so we 
should close it.

I think the condition in out_error should be if (state > 0).

Best regards,
David