From: Alexander Duyck <alexander.duyck@gmail.com>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: Netdev <netdev@vger.kernel.org>,
Timur Tabi <timur@codeaurora.org>,
sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
intel-wired-lan <intel-wired-lan@lists.osuosl.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/7] e1000: eliminate duplicate barriers on weakly-ordered archs
Date: Wed, 14 Mar 2018 18:41:51 -0700 [thread overview]
Message-ID: <CAKgT0UfJwYFy5g_2TE5W4MgdEvyH2CvBAS2imdw9UUiumuUOhQ@mail.gmail.com> (raw)
In-Reply-To: <1520997629-17361-6-git-send-email-okaya@codeaurora.org>
On Tue, Mar 13, 2018 at 8:20 PM, Sinan Kaya <okaya@codeaurora.org> wrote:
> Code includes wmb() followed by writel(). writel() already has a barrier
> on some architectures like arm64.
>
> This ends up CPU observing two barriers back to back before executing the
> register write.
>
> Since code already has an explicit barrier call, changing writel() to
> writel_relaxed().
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/net/ethernet/intel/e1000/e1000_main.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index 3dd4aeb..e0e583a 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -4573,7 +4573,7 @@ e1000_alloc_jumbo_rx_buffers(struct e1000_adapter *adapter,
> * such as IA-64).
> */
> wmb();
> - writel(i, adapter->hw.hw_addr + rx_ring->rdt);
> + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->rdt);
> }
> }
>
> @@ -4688,7 +4688,7 @@ static void e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
> * such as IA-64).
> */
> wmb();
> - writel(i, hw->hw_addr + rx_ring->rdt);
> + writel_relaxed(i, hw->hw_addr + rx_ring->rdt);
> }
> }
>
So you missed the writel in e1000_xmit_frame. You should probably get
that one too while you are doing these updates. The wmb() is in
e1000_tx_queue().
next prev parent reply other threads:[~2018-03-15 1:41 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-14 3:20 [PATCH 1/7] i40e/i40evf: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-14 3:20 ` [PATCH 2/7] ixgbe: eliminate " Sinan Kaya
2018-03-15 1:47 ` Alexander Duyck
2018-03-14 3:20 ` [PATCH 3/7] RDMA/qedr: " Sinan Kaya
2018-03-14 4:12 ` Jason Gunthorpe
2018-03-14 12:06 ` okaya
2018-03-15 22:23 ` Jason Gunthorpe
2018-03-14 3:20 ` [PATCH 4/7] igbvf: " Sinan Kaya
2018-03-15 1:48 ` Alexander Duyck
2018-03-14 3:20 ` [PATCH 5/7] igb: " Sinan Kaya
2018-03-15 1:50 ` Alexander Duyck
2018-03-14 3:20 ` [PATCH 6/7] e1000: " Sinan Kaya
2018-03-15 1:41 ` Alexander Duyck [this message]
2018-03-15 23:30 ` Sinan Kaya
2018-03-16 0:25 ` Alexander Duyck
2018-03-16 0:50 ` Sinan Kaya
2018-03-14 3:20 ` [PATCH 7/7] ixgbevf: " Sinan Kaya
2018-03-14 5:08 ` Timur Tabi
2018-03-14 12:13 ` okaya
2018-03-14 21:49 ` Alexander Duyck
2018-03-14 22:57 ` Sinan Kaya
2018-03-15 1:44 ` Alexander Duyck
2018-03-15 2:17 ` Sinan Kaya
2018-03-15 14:32 ` Alexander Duyck
2018-03-15 16:21 ` Sinan Kaya
2018-03-15 16:27 ` Sinan Kaya
2018-03-15 16:58 ` Alexander Duyck
2018-03-15 1:45 ` Alexander Duyck
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