Re: Buffer locking is special (hints, checksums, AIO writes)

From: Andres Freund <andres(at)anarazel(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>, Kirill Reshke <reshkekirill(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
Subject: Re: Buffer locking is special (hints, checksums, AIO writes)
Date: 2026-01-15 23:26:18
Message-ID: ofzsidrczxdvxjtqxeb56qzfp6cw2sqkogds6phxkpnzssvtb5@jeibq7mlzgoy
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On 2026-01-15 18:19:41 -0500, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > Can't quite decide between just using always_inline - after all the buffer
> > locking really is a rather crucial code path - and just initializing
> > wait_event to 0. Either seems better than using a default:.
>
> Yeah, I agree with not using a default: in case we ever extend
> the mode enum. I'd be inclined to fix it like this:
>
> case BUFFER_LOCK_UNLOCK:
> pg_unreachable();
> + /* silence possible compiler warning: */
> + wait_event = 0;
> }

Unfortunately that doesn't seem to do the trick, at least not locally (gcc
14). I think gcc is considering the case where mode has a value outside of the
known values of the enum. Hence needing initialize wait_event to zero in the
declaration to avoid the warning.

Greetings,

Andres Freund

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