RE: [PATCH net-next 1/2] net: stmmac: fix unsafe MTL DMA macro

[Chang, Junxiao]

Thank you for reviewing it. There is no real issue if this macro only be used in stmmac driver and parameter is not function or "i++".

I will squash these two patches.

Regards,
Junxiao

-----Original Message-----
From: Jakub Kicinski <kuba@xxxxxxxxxx> 
Sent: Tuesday, October 25, 2022 12:00 PM
To: Chang, Junxiao <junxiao.chang@xxxxxxxxx>
Cc: peppe.cavallaro@xxxxxx; alexandre.torgue@xxxxxxxxxxx; joabreu@xxxxxxxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; pabeni@xxxxxxxxxx; mcoquelin.stm32@xxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH net-next 1/2] net: stmmac: fix unsafe MTL DMA macro

On Fri, 21 Oct 2022 19:47:10 +0800 Junxiao Chang wrote:
> Macro like "#define abc(x) (x, x)" is unsafe which might introduce 
> side effects. Each MTL RxQ DMA channel mask is 4 bits, so using (0xf 
> << chan) instead of GENMASK(x + 3, x) to avoid unsafe macro.
> 
> Fixes: d43042f4da3e ("net: stmmac: mapping mtl rx to dma channel")

You need to point out an existing usage where this is causing problems, otherwise this is not a fix.

And squash the two patches together, it's going to be easier to review.