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From: Richard Guo <[email protected]>
To: Ranier Vilela <[email protected]>
Cc: Pg Hackers <[email protected]>
Subject: Re: Avoid unncessary always true test (src/backend/storage/buffer/bufmgr.c)
Date: Mon, 5 Jun 2023 10:37:10 +0800
Message-ID: <CAMbWs4_Jv4p_ib2ZZvUYhgoeSpOABjAW_4chkAhrSU=iW8CRGA@mail.gmail.com> (raw)
In-Reply-To: <CAEudQAoSA7saBF7RaoYbRjE+Zojojin0Qc9A4hebPKB8o1J+EQ@mail.gmail.com>
References: <CAEudQAoSA7saBF7RaoYbRjE+Zojojin0Qc9A4hebPKB8o1J+EQ@mail.gmail.com>

On Sun, Jun 4, 2023 at 8:42 PM Ranier Vilela <[email protected]> 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'.  So for
the same consideration, the test in ExtendBufferedRelShared might be
still needed?  But I'm not familiar with the arounding codes, so need
someone else to confirm that.

Thanks
Richard

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