From: David Hildenbrand <david@redhat.com>
To: Collin Walling <walling@linux.ibm.com>,
qemu-devel@nongnu.org, qemu-s390x@nongnu.org
Cc: thuth@redhat.com, frankja@linux.ibm.com, mst@redhat.com,
cohuck@redhat.com, pasic@linux.ibm.com, borntraeger@de.ibm.com,
svens@linux.ibm.com, pbonzini@redhat.com, mihajlov@linux.ibm.com,
rth@twiddle.net
Subject: Re: [PATCH v4 3/8] s390/sclp: rework sclp boundary and length checks
Date: Tue, 21 Jul 2020 10:41:47 +0200 [thread overview]
Message-ID: <bd373fb2-20d3-baf4-f2bc-4eca1f033c2b@redhat.com> (raw)
In-Reply-To: <c7ba363c-a142-9fb9-2ecf-a8dc56a6e6f8@linux.ibm.com>
[...]
>>> + switch (code & SCLP_CMD_CODE_MASK) {
>>> + default:
>>> + if (sccb_max_addr < sccb_boundary) {
>>> + return true;
>>> + }
>>> + }
>>
>> ^ what is that?
>>
>> if ((code & SCLP_CMD_CODE_MASK) && sccb_max_addr < sccb_boundary) {
>> return true;
>> }
Oh, my tired eyes missed that it's actually only
if (sccb_max_addr < sccb_boundary) :)
>>
>
> I agree it looks pointless in this patch, but it makes more sense in
> patch #6 where we introduce cases for the SCLP commands that bypass
> these checks if the extended-length sccb feature is enabled.
I am really a friend of introducing stuff where needed. Just use a
simple "if" here and convert to the switch in patch #6.
>
>>> + header->response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
>>> + return false;
>>
>> So we return "false" on success? At least I consider that weird when
>> returning the bool type. Maybe make it clearer what the function indicates
>>
>
> Hmmm... I figured since there were more paths that can lead to success
> (i.e. when I introduce the feat check in a later patch), then it made
> more sense to to return false at the end. sclp_command_code_valid has
> similar logic.
>
> But if boolean functions traditionally return true as the last return
> value, I can rework it to align to coding preferences / standards.
>
>> "sccb_boundary_is_invalid"
>>
>
> Unless it's simply the name that is confusing?
The options I would support are
1. "sccb_boundary_is_valid" which returns "true" if valid
2. "sccb_boundary_is_invalid" which returns "true" if invalid
3. "sccb_boundary_validate" which returns "0" if valid and -EINVAL if not.
Which makes reading this code a bit easier.
>
>> or leave it named as is and switch from return value "bool" to "int",
>> using "0" on success and "-EINVAL" on error.
>>
>
> Is the switch statement an overkill? I thought of it as a cleaner way to
> later show which commands have a special conditions (introduced in patch
> 6 for the ELS stuff) instead of a nasty long if statement.
I think the switch make sense in patch #6.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-07-21 8:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 20:23 [PATCH v4 0/8] s390: Extended-Length SCCB & DIAGNOSE 0x318 Collin Walling
2020-06-24 20:23 ` [PATCH v4 1/8] s390/sclp: get machine once during read scp/cpu info Collin Walling
2020-06-24 20:23 ` [PATCH v4 2/8] s390/sclp: check sccb len before filling in data Collin Walling
2020-06-24 20:23 ` [PATCH v4 3/8] s390/sclp: rework sclp boundary and length checks Collin Walling
2020-06-25 6:29 ` Thomas Huth
2020-07-20 8:17 ` David Hildenbrand
2020-07-20 20:06 ` Collin Walling
2020-07-21 8:41 ` David Hildenbrand [this message]
2020-07-21 18:40 ` Collin Walling
2020-07-23 6:26 ` Cornelia Huck
2020-07-24 15:06 ` Collin Walling
2020-06-24 20:23 ` [PATCH v4 4/8] s390/sclp: read sccb from mem based on sccb length Collin Walling
2020-07-20 8:19 ` David Hildenbrand
2020-07-20 20:06 ` Collin Walling
2020-06-24 20:23 ` [PATCH v4 5/8] s390/sclp: use cpu offset to locate cpu entries Collin Walling
2020-06-24 20:23 ` [PATCH v4 6/8] s390/sclp: add extended-length sccb support for kvm guest Collin Walling
2020-06-26 10:01 ` Cornelia Huck
2020-07-15 15:35 ` Collin Walling
2020-07-15 16:05 ` Cornelia Huck
2020-06-24 20:23 ` [PATCH v4 7/8] s390/kvm: header sync for diag318 Collin Walling
2020-06-24 20:23 ` [PATCH v4 8/8] s390: guest support for diagnose 0x318 Collin Walling
2020-06-26 10:03 ` Cornelia Huck
2020-07-15 15:36 ` [PATCH v4 0/8] s390: Extended-Length SCCB & DIAGNOSE 0x318 Collin Walling
2020-07-15 16:04 ` Cornelia Huck
2020-07-15 16:26 ` Collin Walling
2020-07-16 12:02 ` Cornelia Huck
2020-09-09 7:54 ` Christian Borntraeger
2020-09-09 8:46 ` Cornelia Huck
2020-09-09 9:43 ` Cornelia Huck
2020-09-09 18:13 ` Collin Walling
2020-09-10 6:38 ` Cornelia Huck
2020-09-10 6:49 ` Collin Walling
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