Re: Avoid unncessary always true test (src/backend/storage/buffer/bufmgr.c)

Em seg., 5 de jun. de 2023 às 08:06, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
escreveu:

> Em dom., 4 de jun. de 2023 às 23:37, Richard Guo <guofenglinux(at)gmail(dot)com>
> escreveu:
>
>>
>> On Sun, Jun 4, 2023 at 8:42 PM Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> wrote:
>>
>>> Hi,
>>>
>>> Per Coverity.
>>>
>>> At function ExtendBufferedRelShared, has a always true test.
>>> eb.rel was dereferenced one line above, so in
>>> if (eb.rel) is always true.
>>>
>>> I think it's worth removing the test, because Coverity raises dozens of
>>> alerts thinking eb.rel might be NULL.
>>> Besides, one less test is one less branch.
>>>
>>
>> This also happens in ExtendBufferedRelTo, and the comment there explains
>> that the eb.rel 'could have been closed while waiting for lock'.
>>
> Well, RelationGetSmgr also dereferences eb.rel.
> If eb.rel could be closed while waiting for lock,
> anyone who references eb.rel below takes a risk?
>
> static inline SMgrRelation
> RelationGetSmgr(Relation rel)
> {
> if (unlikely(rel->rd_smgr == NULL))
> smgrsetowner(&(rel->rd_smgr), smgropen(rel->rd_locator, rel->rd_backend));
> return rel->rd_smgr;
> }
>
Sorry Richard, nevermind.

My fault, I withdraw this patch.

regards,
Ranier Vilela