linux-kernel - Re: [PATCH 4/6] fixdep: refactor hash table lookup

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Message-ID: <CANiq72n6ZLcNRh=Ec1xCSNJtb=KZNMA-MMrtd8=DyUL4-2i_0w@mail.gmail.com>
Date:   Tue, 3 Jan 2023 21:45:50 +0100
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Miguel Ojeda <ojeda@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>
Subject: Re: [PATCH 4/6] fixdep: refactor hash table lookup

On Sat, Dec 31, 2022 at 7:42 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> +/*
> + * Lookup a string in the hash table. If found, just return true.
> + * If not, add it to the hashtable and return false.
> + */
> +static bool in_hashtable(const char *name, int len, struct item *hashtab[])

I think readers may find a bit surprising that a function named
`in_hashtable` mutates the table. Should we use a better name? Perhaps
`ensure_in_hashtable`?

In other words, the function is really "insert if not already there
and return the previous state". Similar methods in C++ and Rust are
called `insert`, though they return the opposite, i.e. whether the
insertion took place. If we did that, then `insert_into_hashtable` may
be a good name instead.

> +       unsigned int hash = strhash(name, len);

Nit: this could be `const`, but I see we are not using it in
`fixdep.c` (for non-pointees) and it was not done in the original. But
it could be nice to start...

Reviewed-by: Miguel Ojeda <ojeda@...nel.org>
Tested-by: Miguel Ojeda <ojeda@...nel.org>

Cheers,
Miguel