[PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs_init

[PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs_init

[Nathan Chancellor]

When building for 32-bit ARM, there is a link time error because of a
64-bit division:

ld.lld: error: undefined symbol: __aeabi_uldivmod
>>> referenced by spectrum_buffers.c
>>>               net/ethernet/mellanox/mlxsw/spectrum_buffers.o:(mlxsw_sp_buffers_init) in archive drivers/built-in.a
>>> did you mean: __aeabi_uidivmod
>>> defined in: arch/arm/lib/lib.a(lib1funcs.o

Avoid this by using div_u64, which is designed to avoid this problem.

Fixes: bc9f6e94bcb5 ("mlxsw: spectrum_buffers: Calculate the size of the main pool")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
index 33a978af80d6..968f0902e4fe 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c
@@ -470,7 +470,7 @@ static int mlxsw_sp_sb_prs_init(struct mlxsw_sp *mlxsw_sp,
 				size_t prs_len)
 {
 	/* Round down, unlike mlxsw_sp_bytes_cells(). */
-	u32 sb_cells = mlxsw_sp->sb->sb_size / mlxsw_sp->sb->cell_size;
+	u32 sb_cells = div_u64(mlxsw_sp->sb->sb_size, mlxsw_sp->sb->cell_size);
 	u32 rest_cells[2] = {sb_cells, sb_cells};
 	int i;
 	int err;
-- 
2.24.0.rc1

Re: [PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs_init

[Ido Schimmel]

On Wed, Oct 30, 2019 at 09:01:52AM -0700, Nathan Chancellor wrote:
> When building for 32-bit ARM, there is a link time error because of a
> 64-bit division:
> 
> ld.lld: error: undefined symbol: __aeabi_uldivmod
> >>> referenced by spectrum_buffers.c
> >>>               net/ethernet/mellanox/mlxsw/spectrum_buffers.o:(mlxsw_sp_buffers_init) in archive drivers/built-in.a
> >>> did you mean: __aeabi_uidivmod
> >>> defined in: arch/arm/lib/lib.a(lib1funcs.o
> 
> Avoid this by using div_u64, which is designed to avoid this problem.
> 
> Fixes: bc9f6e94bcb5 ("mlxsw: spectrum_buffers: Calculate the size of the main pool")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>

Thanks, Nathan!

Re: [PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs_init

[David Miller]

From: Nathan Chancellor <natechancellor@gmail.com>
Date: Wed, 30 Oct 2019 09:01:52 -0700

> When building for 32-bit ARM, there is a link time error because of a
> 64-bit division:
> 
> ld.lld: error: undefined symbol: __aeabi_uldivmod
>>>> referenced by spectrum_buffers.c
>>>>               net/ethernet/mellanox/mlxsw/spectrum_buffers.o:(mlxsw_sp_buffers_init) in archive drivers/built-in.a
>>>> did you mean: __aeabi_uidivmod
>>>> defined in: arch/arm/lib/lib.a(lib1funcs.o
> 
> Avoid this by using div_u64, which is designed to avoid this problem.
> 
> Fixes: bc9f6e94bcb5 ("mlxsw: spectrum_buffers: Calculate the size of the main pool")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Applied, thanks.