linux-kernel - Re: [PATCH v2] LoongArch: Add jump-label implementation

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Message-ID: <20230511074359.GQ4253@hirez.programming.kicks-ass.net>
Date:   Thu, 11 May 2023 09:43:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Youling Tang <tangyouling@...ngson.cn>
Cc:     WANG Xuerui <kernel@...0n.name>,
        Huacai Chen <chenhuacai@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Jason Baron <jbaron@...mai.com>,
        Zhangjin Wu <falcon@...ylab.org>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev
Subject: Re: [PATCH v2] LoongArch: Add jump-label implementation

On Thu, May 11, 2023 at 09:33:37AM +0800, Youling Tang wrote:

> > > +void arch_jump_label_transform(struct jump_entry *entry,
> > > +                   enum jump_label_type type)
> > > +{
> > > +    void *addr = (void *)jump_entry_code(entry);
> > > +    u32 insn;
> > > +
> > > +    if (type == JUMP_LABEL_JMP)
> > 
> > Please use a switch for dealing with enum-typed values.
> 
> Because the current type only has JUMP_LABEL_NOP and JUMP_LABEL_JMP,
> using if may be simpler than switch.

IIRC we used an enum with descriptive names instead of a boolean because
true/false just doesn't tell you much.

The whole thing fundamentally is a boolean descision though, either
you write a JMP or a NOP, jump-labels don't have more options.