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From: Randy Dunlap <rdunlap@infradead.org>
To: Nathan Chancellor <natechancellor@gmail.com>,
	Jiri Pirko <jiri@mellanox.com>,
	Ido Schimmel <idosch@mellanox.com>,
	"David S. Miller" <davem@davemloft.net>
Cc: Petr Machata <petrm@mellanox.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mlxsw: spectrum_qdisc: Fix 64-bit division error in mlxsw_sp_qdisc_tbf_rate_kbps
Date: Thu, 30 Jan 2020 17:43:56 -0800	[thread overview]
Message-ID: <31537c12-8f17-660d-256d-e702d1121367@infradead.org> (raw)
In-Reply-To: <20200130232641.51095-1-natechancellor@gmail.com>

On 1/30/20 3:26 PM, Nathan Chancellor wrote:
> When building arm32 allmodconfig:
> 
> ERROR: "__aeabi_uldivmod"
> [drivers/net/ethernet/mellanox/mlxsw/mlxsw_spectrum.ko] undefined!
> 
> rate_bytes_ps has type u64, we need to use a 64-bit division helper to
> avoid a build error.
> 
> Fixes: a44f58c41bfb ("mlxsw: spectrum_qdisc: Support offloading of TBF Qdisc")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>  drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> index 79a2801d59f6..65e681ef01e8 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> @@ -614,7 +614,7 @@ mlxsw_sp_qdisc_tbf_rate_kbps(struct tc_tbf_qopt_offload_replace_params *p)
>  	/* TBF interface is in bytes/s, whereas Spectrum ASIC is configured in
>  	 * Kbits/s.
>  	 */
> -	return p->rate.rate_bytes_ps / 1000 * 8;
> +	return div_u64(p->rate.rate_bytes_ps, 1000 * 8);

not quite right AFAICT.

try either
	return div_u64(p->rate.rate_bytes_ps * 8, 1000);
or
	return div_u64(p->rate.rate_bytes_ps, 1000) * 8;

>  }
>  
>  static int
> 


-- 
~Randy


  reply	other threads:[~2020-01-31  1:44 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-30 23:26 [PATCH] mlxsw: spectrum_qdisc: Fix 64-bit division error in mlxsw_sp_qdisc_tbf_rate_kbps Nathan Chancellor
2020-01-31  1:43 ` Randy Dunlap [this message]
2020-01-31  1:48   ` Nathan Chancellor
2020-02-03 10:03     ` Petr Machata
2020-01-31  1:51 ` [PATCH v2] " Nathan Chancellor
2020-01-31 13:47   ` Ido Schimmel
2020-01-31 14:27   ` Jiri Pirko
2020-01-31 16:55   ` Jakub Kicinski

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