t;> linux-arm-...@vger.kernel.org; linux-arm-ker...@lists.infradead.org; Elior,
>> Ariel ; Dept-Eng Everest Linux L2 > engeverestlinu...@cavium.com>; linux-ker...@vger.kernel.org
>> Subject: Re: [PATCH v5 3/5] bnx2x: Eliminate duplicate barriers on weakly-
>> ordered ar
fradead.org; Elior,
> Ariel ; Dept-Eng Everest Linux L2 engeverestlinu...@cavium.com>; linux-ker...@vger.kernel.org
> Subject: Re: [PATCH v5 3/5] bnx2x: Eliminate duplicate barriers on weakly-
> ordered archs
>
> On 3/23/2018 1:04 PM, David Miller wrote:
> > From: Sinan Kaya
From: Sinan Kaya
Date: Fri, 23 Mar 2018 13:13:46 -0400
> We have decided to drop a similar patch on Infiniband due to incorrect
> usage of barrier(). If you feel strongly about it, I can remove the
> DOORBELL change.
Either remove the DOORBELL change or properly adjust the barrier() to
be a wmb(
On 3/23/2018 1:04 PM, David Miller wrote:
> From: Sinan Kaya
> Date: Fri, 23 Mar 2018 12:51:47 -0400
>
>> It could if txdata->tx_db was not a union. There is a data dependency
>> between txdata->tx_db.data.prod and txdata->tx_db.raw.
>>
>> So, no reordering.
>
> I don't see it that way, the cod
From: Sinan Kaya
Date: Fri, 23 Mar 2018 12:51:47 -0400
> It could if txdata->tx_db was not a union. There is a data dependency
> between txdata->tx_db.data.prod and txdata->tx_db.raw.
>
> So, no reordering.
I don't see it that way, the code requires that:
txdata->tx_db.data.prod += nb
On 3/23/2018 12:43 PM, David Miller wrote:
> From: Sinan Kaya
> Date: Fri, 23 Mar 2018 12:31:12 -0400
>
>> Sorry, you got me confused now.
>>
>> If you look at the code closer, you'll see this.
>>
>> wmb();
>>
>> txdata->tx_db.data.prod += nbd;
>> barrier();
>>
>> DOORBELL(bp,
From: Sinan Kaya
Date: Fri, 23 Mar 2018 12:31:12 -0400
> Sorry, you got me confused now.
>
> If you look at the code closer, you'll see this.
>
> wmb();
>
> txdata->tx_db.data.prod += nbd;
> barrier();
>
> DOORBELL(bp, txdata->cid, txdata->tx_db.raw);
>
> and you also
On 3/23/2018 12:20 PM, David Miller wrote:
> From: Sinan Kaya
> Date: Thu, 22 Mar 2018 13:10:00 -0400
>
>> Code includes wmb() followed by writel(). writel() already has a
>> barrier on some architectures like arm64.
> ...
>> @@ -4155,7 +4155,7 @@ netdev_tx_t bnx2x_start_xmit(struct sk_buff *skb
From: Sinan Kaya
Date: Thu, 22 Mar 2018 13:10:00 -0400
> Code includes wmb() followed by writel(). writel() already has a
> barrier on some architectures like arm64.
...
> @@ -4155,7 +4155,7 @@ netdev_tx_t bnx2x_start_xmit(struct sk_buff *skb,
> struct net_device *dev)
> txdata->tx_db.dat
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-
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