linux-kernel - Re: [PATCH, net-next] i40e: avoid 64-bit division where possible

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Date:   Tue, 17 Oct 2017 08:14:54 -0700
From:   Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Jacob Keller <jacob.e.keller@...el.com>,
        Mitch Williams <mitch.a.williams@...el.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Amritha Nambiar <amritha.nambiar@...el.com>,
        Filip Sadowski <filip.sadowski@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH, net-next] i40e: avoid 64-bit division where possible

On Tue, 2017-10-17 at 12:23 +0200, Arnd Bergmann wrote:
> The new bandwidth calculation causes a link error on 32-bit
> architectures, like
> 
> ERROR: "__aeabi_uldivmod" [drivers/net/ethernet/intel/i40e/i40e.ko]
> undefined!
> 
> The problem is the max_tx_rate calculation that uses 64-bit integers.
> This is not really necessary since the numbers are in MBit/s so
> they won't be higher than 40000 for the highest support rate, and
> are guaranteed to not exceed 2^32 in future generations either.
> 
> This changes the representation to 'u32' when dealing with MBit/s
> and uses div_u64() to convert from u64 numbers in byte/s.
> 
> Fixes: 2027d4deacb1 ("i40e: Add support setting TC max bandwidth
> rates")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/net/ethernet/intel/i40e/i40e.h      |  4 ++--
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 27 ++++++++++++++-----
> --------
>  2 files changed, 16 insertions(+), 15 deletions(-)

Unfortunately your patch does not apply cleanly to my tree.  Arnd,
could you please rebase your patch based my next-queue tree (dev-queue
branch)?  I already have several i40e patches queued up and applied to
that branch.
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