[PATCH] net/mlx5: IPSec, fix 64-bit division correctly

[Arnd Bergmann]

The new IPSec offload code introduced a build error:

drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.o: In function 
`mlx5e_ipsec_build_inverse_table':
ipsec_rxtx.c:(.text+0x556): undefined reference

Another patch was added on top to fix the build error, but
that introduced a new bug, as we now use the remainder of
the division rather than the result.

This makes it use the correct helper function instead.

Fixes: 5dfd87b67cd9 ("net/mlx5: IPSec, Fix 64-bit division on 32-bit builds")
Fixes: 2ac9cfe78223 ("net/mlx5e: IPSec, Add Innova IPSec offload TX data path")
Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c
index 7d06c673851a..4614ddfa91eb 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c
@@ -363,7 +363,6 @@ void mlx5e_ipsec_build_inverse_table(void)
 {
        u16 mss_inv;
        u32 mss;
-       u64 n;
 
        /* Calculate 1/x inverse table for use in GSO data path.
         * Using this table, we provide the IPSec accelerator with the value of
@@ -373,8 +372,7 @@ void mlx5e_ipsec_build_inverse_table(void)
         */
        mlx5e_ipsec_inverse_table[1] = htons(0xFFFF);
        for (mss = 2; mss < MAX_LSO_MSS; mss++) {
-               n = 1ULL << 32;
-               mss_inv = do_div(n, mss) >> 16;
+               mss_inv = div_u64(1ULL << 32, mss) >> 16;
                mlx5e_ipsec_inverse_table[mss] = htons(mss_inv);
        }
 }
-- 
2.9.0