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References: <20240125235723.39507-1-vinicius.gomes@intel.com> <20240125235723.39507-2-vinicius.gomes@intel.com>
In-Reply-To: <20240125235723.39507-2-vinicius.gomes@intel.com>
From: Amir Goldstein <amir73il@gmail.com>
Date: Fri, 26 Jan 2024 16:46:08 +0200
Message-ID: <CAOQ4uxgjgQbYy+cHKYM5ZqJm7hKT6oGTty6fvh1_zEX3krptJQ@mail.gmail.com>
Subject: Re: [RFC v2 1/4] cleanup: Fix discarded const warning when defining guards
To: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Cc: brauner@kernel.org, hu1.chen@intel.com, miklos@szeredi.hu, 
	malini.bhandaru@intel.com, tim.c.chen@intel.com, mikko.ylinen@intel.com, 
	lizhen.you@intel.com, linux-unionfs@vger.kernel.org, 
	linux-kernel@vger.kernel.org
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On Fri, Jan 26, 2024 at 1:57=E2=80=AFAM Vinicius Costa Gomes
<vinicius.gomes@intel.com> wrote:
>
> When defining guards for const types the void* return implicitly
> discards the const modifier. Be explicit about it.
>
> Compiler warning (gcc 13.2.1):
>
> ./include/linux/cleanup.h:154:18: warning: return discards =E2=80=98const=
=E2=80=99 qualifier from pointer target type [-Wdiscarded-qualifiers]
>   154 |         { return *_T; }
>       |                  ^~~
> ./include/linux/cred.h:193:1: note: in expansion of macro =E2=80=98DEFINE=
_GUARD=E2=80=99
>   193 | DEFINE_GUARD(cred, const struct cred *, _T =3D override_creds_lig=
ht(_T),
>       | ^~~~~~~~~~~~
>

I did not look closely, but can't you use DEFINE_LOCK_GUARD_1()?

Thanks,
Amir.