Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Andreas Dilger <adilger@dilger.ca>
Message-Id: <AAB32610-D238-4137-96DE-33655AAAB545@dilger.ca>
Content-Type: multipart/signed;
 boundary="Apple-Mail=_7F4BCA94-4C48-4AE3-93D5-5577EE984D3A";
 protocol="application/pgp-signature"; micalg=pgp-sha256
Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\))
Subject: Re: [PATCH] ext4: Remove unreachable code
Date:   Fri, 29 Jan 2021 23:42:20 -0700
In-Reply-To: <20210129185856.158310-1-viniciustinti@gmail.com>
Cc:     Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Nathan Chancellor <natechancellor@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
To:     Vinicius Tinti <viniciustinti@gmail.com>
References: <20210129185856.158310-1-viniciustinti@gmail.com>
Precedence: bulk


--Apple-Mail=_7F4BCA94-4C48-4AE3-93D5-5577EE984D3A
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii

On Jan 29, 2021, at 11:58 AM, Vinicius Tinti <viniciustinti@gmail.com> =
wrote:
>=20
> By enabling -Wunreachable-code-aggressive on Clang the following code
> paths are unreachable.
>=20
> Commit dd73b5d5cb67 ("ext4: convert dx_probe() to use the ERR_PTR
> convention")
> Commit ac27a0ec112a ("[PATCH] ext4: initial copy of files from ext3")
>=20
> Clang warns:
>=20
> fs/ext4/namei.c:831:17: warning: code will never be executed
> [-Wunreachable-code]
>                        unsigned n =3D count - 1;
>                                     ^~~~~
> fs/ext4/namei.c:830:7: note: silence by adding parentheses to mark =
code as
> explicitly dead
>                if (0) { // linear search cross check
>                    ^
>                    /* DISABLES CODE */ ( )
>=20
> Signed-off-by: Vinicius Tinti <viniciustinti@gmail.com>
> ---
> fs/ext4/namei.c | 15 ---------------
> 1 file changed, 15 deletions(-)
>=20
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index cf652ba3e74d..1f64dbd7237b 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -827,21 +827,6 @@ dx_probe(struct ext4_filename *fname, struct =
inode *dir,
> 				p =3D m + 1;
> 		}
>=20
> -		if (0) { // linear search cross check

I would rather put this block under "#ifdef DX_DEBUG" so that it is =
available
in the future for debugging problems with hashed directories.

> -			unsigned n =3D count - 1;
> -			at =3D entries;
> -			while (n--)
> -			{
> -				dxtrace(printk(KERN_CONT ","));
> -				if (dx_get_hash(++at) > hash)
> -				{
> -					at--;
> -					break;
> -				}
> -			}
> -			ASSERT(at =3D=3D p - 1);
> -		}
> -
> 		at =3D p - 1;
> 		dxtrace(printk(KERN_CONT " %x->%u\n",
> 			       at =3D=3D entries ? 0 : dx_get_hash(at),
> --
> 2.25.1
>=20


Cheers, Andreas


--Apple-Mail=_7F4BCA94-4C48-4AE3-93D5-5577EE984D3A
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
	filename=signature.asc
Content-Type: application/pgp-signature;
	name=signature.asc
Content-Description: Message signed with OpenPGP

-----BEGIN PGP SIGNATURE-----
Comment: GPGTools - http://gpgtools.org
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=rYW5
-----END PGP SIGNATURE-----

--Apple-Mail=_7F4BCA94-4C48-4AE3-93D5-5577EE984D3A--