| Message ID | 20170914110628.3590833-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | net/mlx5: fpga: avoid uninitialized return codes | expand |
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: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] > drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c:126:6: error: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] > > 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. 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_device *fdev, size_t size, if (!fdev->mdev) return -ENOTCONN; + if (!size) + return -EINVAL; + while (bytes_done < size) { actual_size = min(max_size, (size - bytes_done)); Thanks > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82203 > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > 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/drivers/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_device *fdev, size_t size, > size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; > size_t bytes_done = 0; > u8 actual_size; > - int err; > + int err = -EINVAL; > > if (!fdev->mdev) > return -ENOTCONN; > @@ -93,7 +93,7 @@ static int mlx5_fpga_mem_write_i2c(struct mlx5_fpga_device *fdev, size_t size, > size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; > size_t bytes_done = 0; > u8 actual_size; > - int err; > + int err = -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
On Thu, Sep 14, 2017 at 5:54 AM, Leon Romanovsky <leonro@mellanox.com> wrote: > 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: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] >> drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c:126:6: error: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] >> >> 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_device *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 = min(max_size, (size - bytes_done)); > > Thanks > >> >> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82203 >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> --- >> 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/drivers/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_device *fdev, size_t size, >> size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; >> size_t bytes_done = 0; >> u8 actual_size; >> - int err; >> + int err = -EINVAL; >> >> if (!fdev->mdev) >> return -ENOTCONN; >> @@ -93,7 +93,7 @@ static int mlx5_fpga_mem_write_i2c(struct mlx5_fpga_device *fdev, size_t size, >> size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; >> size_t bytes_done = 0; >> u8 actual_size; >> - int err; >> + int err = -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
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c b/drivers/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_device *fdev, size_t size, size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; size_t bytes_done = 0; u8 actual_size; - int err; + int err = -EINVAL; if (!fdev->mdev) return -ENOTCONN; @@ -93,7 +93,7 @@ static int mlx5_fpga_mem_write_i2c(struct mlx5_fpga_device *fdev, size_t size, size_t max_size = MLX5_FPGA_ACCESS_REG_SIZE_MAX; size_t bytes_done = 0; u8 actual_size; - int err; + int err = -EINVAL; if (!fdev->mdev) return -ENOTCONN;
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: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c:126:6: error: ‘err’ may be used uninitialized in this function [-Werror=uninitialized] 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. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82203 Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.9.0