linux-kernel - Re: [PATCH v3 06/15] futex: FLAGS

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Message-ID: <87y1gzh82t.ffs@tglx>
Date:   Thu, 21 Sep 2023 17:14:34 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     peterz@...radead.org, axboe@...nel.dk
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, dvhart@...radead.org, dave@...olabs.net,
        andrealmeid@...lia.com, Andrew Morton <akpm@...ux-foundation.org>,
        urezki@...il.com, hch@...radead.org, lstoakes@...il.com,
        Arnd Bergmann <arnd@...db.de>, linux-api@...r.kernel.org,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        malteskarupke@....de
Subject: Re: [PATCH v3 06/15] futex: FLAGS_STRICT

On Thu, Sep 21 2023 at 12:45, peterz@...radead.org wrote:
> The current semantics for futex_wake() are a bit loose, specifically
> asking for 0 futexes to be woken actually gets you 1.
>
> Adding a !nr check to sys_futex_wake() makes that it would return 0
> for unaligned futex words, because that check comes in the shared
> futex_wake() function. Adding the !nr check there, would affect the
> legacy sys_futex() semantics.
>
> Hence frob a flag :-(
>
> Suggested-by: André Almeida <andrealmeid@...lia.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>