Re: [REGRESSION] v6.8 SMC-D issues

Wen Gu
2024-01-25T09:28:53Z

On 2024/1/25 16:26, Alexandra Winter wrote:
>
>
> On 25.01.24 05:59, Wen Gu wrote:
>> After a while debug I found an elementary mistake of mine in
>> b40584d ("net/smc: compatible with 128-bits extended GID of virtual ISM device")..
>>
>> The operator order in smcd_lgr_match() is not as expected. It will always return
>> 'true' in remote-system case.
>>
>>  static bool smcd_lgr_match(struct smc_link_group *lgr,
>> -                          struct smcd_dev *smcismdev, u64 peer_gid)
>> +                          struct smcd_dev *smcismdev,
>> +                          struct smcd_gid *peer_gid)
>>  {
>> -       return lgr->peer_gid == peer_gid && lgr->smcd == smcismdev;
>> +       return lgr->peer_gid.gid == peer_gid->gid && lgr->smcd == smcismdev &&
>> +               smc_ism_is_virtual(smcismdev) ?
>> +               (lgr->peer_gid.gid_ext == peer_gid->gid_ext) : 1;
>>  }
>>
>> Could you please try again with this patch? to see if this is the root cause.
>> Really sorry for the inconvenience.
>>
>> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
>> index da6a8d9c81ea..c6a6ba56c9e3 100644
>> --- a/net/smc/smc_core.c
>> +++ b/net/smc/smc_core.c
>> @@ -1896,8 +1896,8 @@ static bool smcd_lgr_match(struct smc_link_group *lgr,
>>                            struct smcd_gid *peer_gid)
>>  {
>>         return lgr->peer_gid.gid == peer_gid->gid && lgr->smcd == smcismdev &&
>> -               smc_ism_is_virtual(smcismdev) ?
>> -               (lgr->peer_gid.gid_ext == peer_gid->gid_ext) : 1;
>> +               (smc_ism_is_virtual(smcismdev) ?
>> +                (lgr->peer_gid.gid_ext == peer_gid->gid_ext) : 1);
>>  }
>>
>>
>> Thanks,
>> Wen Gu
>
> Hello Wen Gu,
>
> thank you for the quick resposne and for finding this nasty bug.
> I can confirm that with your patch I do not see the issue anymore.

Thank you very much for your confirmation, Alexandra.

> Please send a fix to the mailing lists. See
> https://docs.kernel.org/process/handling-regressions.html
> for some tips.
>

Thank you. Will do.

> May I propose that instead of adding the brackets, you change this function
> to an if-then-else sequence for readability and maintainability?
> I would still mention the missing brackets in the commit message, so
> readers can quickly understand the issue.

I agree. if-then-else will make it clearer. I will fix it like this:

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index da6a8d9c81ea..1d5bce82d4d8 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1895,9 +1895,15 @@ static bool smcd_lgr_match(struct smc_link_group *lgr,
struct smcd_dev *smcismdev,
struct smcd_gid *peer_gid)
{
- return lgr->peer_gid.gid == peer_gid->gid && lgr->smcd == smcismdev &&
- smc_ism_is_virtual(smcismdev) ?
- (lgr->peer_gid.gid_ext == peer_gid->gid_ext) : 1;
+ if (lgr->peer_gid.gid != peer_gid->gid ||
+ lgr->smcd != smcismdev)
+ return false;
+
+ if (smc_ism_is_virtual(smcismdev) &&
+ lgr->peer_gid.gid_ext != peer_gid->gid_ext)
+ return false;
+
+ return true;
}

Thanks again,
Wen Gu

>
> Thanks again for the quick response.
> Sandy