linux-kernel - [PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs

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Message-Id: <20191030160152.11305-1-natechancellor@gmail.com>
Date:   Wed, 30 Oct 2019 09:01:52 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Jiri Pirko <jiri@...lanox.com>, Ido Schimmel <idosch@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH net-next] mlxsw: Fix 64-bit division in mlxsw_sp_sb_prs_init

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@...il.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