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SubjectRE: [PATCH] net/mlx5: IPSec, fix 64-bit division correctly
Date
> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@arndb.de]
> Subject: [PATCH] net/mlx5: IPSec, fix 64-bit division correctly
>
> 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 <arnd@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;

Thanks Arnd,

:o
I'm surprised... let me check this...

> mlx5e_ipsec_inverse_table[mss] = htons(mss_inv);
> }
> }
> --
> 2.9.0

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