From mboxrd@z Thu Jan 1 00:00:00 1970 From: Saeed Mahameed Subject: Re: [PATCH] net/mlx5: fpga: avoid uninitialized return codes Date: Thu, 14 Sep 2017 11:39:20 -0700 Message-ID: References: <20170914110628.3590833-1-arnd@arndb.de> <20170914125429.GZ3405@mtr-leonro.local> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20170914125429.GZ3405@mtr-leonro.local> Sender: linux-kernel-owner@vger.kernel.org To: Leon Romanovsky Cc: Arnd Bergmann , Ilan Tayari , Saeed Mahameed , Matan Barak , Boris Pismenny , Linux Netdev List , linux-rdma@vger.kernel.org, linux-kernel List-Id: linux-rdma@vger.kernel.org On Thu, Sep 14, 2017 at 5:54 AM, Leon Romanovsky wrot= e: > On Thu, Sep 14, 2017 at 01:06:18PM +0200, Arnd Bergmann wrote: >> calling mlx5_fpga_mem_{read,write}_i2c() with a zero length on >> older compiler version such as gcc-4.6 results in a warning that >> the return code is not initialized: >> >> drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c:147:6: error: =E2=80= =98err=E2=80=99 may be used uninitialized in this function [-Werror=3Dunini= tialized] >> drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c:126:6: error: =E2=80= =98err=E2=80=99 may be used uninitialized in this function [-Werror=3Dunini= tialized] >> >> On newer compilers, the 'err' variable is optimized away in this >> code path and assumed to be zero when the loop completes, so we >> don't get this warning. >> >> I'm changing the function here to instead return -EINVAL for the >> case, under the assumption that it was never meant to be called >> with a zero length argument. Thanks Arnd, Looks good. > > I agree with you that size can't be zero and this patch will fix the > warning, but if it is possible, I will prefer to have this check is > written explicitly and not implicitly. > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c b/drivers= /net/ethernet/mellanox/mlx5/core/fpga/sdk.c > index 3c11d6e2160a..0e85bebe1dad 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c > @@ -69,6 +69,9 @@ static int mlx5_fpga_mem_read_i2c(struct mlx5_fpga_devi= ce *fdev, size_t size, > if (!fdev->mdev) > return -ENOTCONN; > > + if (!size) > + return -EINVAL; > + Or simply trust the caller :), and avoid redundant code. > while (bytes_done < size) { > actual_size =3D min(max_size, (size - bytes_done)); > > Thanks > >> >> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D82203 >> Signed-off-by: Arnd Bergmann >> --- >> drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c b/driver= s/net/ethernet/mellanox/mlx5/core/fpga/sdk.c >> index 3c11d6e2160a..914fb9d77a1a 100644 >> --- a/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c >> +++ b/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c >> @@ -64,7 +64,7 @@ static int mlx5_fpga_mem_read_i2c(struct mlx5_fpga_dev= ice *fdev, size_t size, >> size_t max_size =3D MLX5_FPGA_ACCESS_REG_SIZE_MAX; >> size_t bytes_done =3D 0; >> u8 actual_size; >> - int err; >> + int err =3D -EINVAL; >> >> if (!fdev->mdev) >> return -ENOTCONN; >> @@ -93,7 +93,7 @@ static int mlx5_fpga_mem_write_i2c(struct mlx5_fpga_de= vice *fdev, size_t size, >> size_t max_size =3D MLX5_FPGA_ACCESS_REG_SIZE_MAX; >> size_t bytes_done =3D 0; >> u8 actual_size; >> - int err; >> + int err =3D -EINVAL; >> >> if (!fdev->mdev) >> return -ENOTCONN; >> -- >> 2.9.0 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html