linux-kernel - Re: [PATCH] devres: Simple code optimization

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Date: Thu, 27 Jun 2024 15:54:41 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Zijun Hu <quic_zijuhu@...cinc.com>
Cc: rafael@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] devres: Simple code optimization

On Thu, Jun 27, 2024 at 09:47:16PM +0800, Zijun Hu wrote:
> Initialize an uninitialized struct member for devres_open_group()
> and simplify devm_percpu_match() implementation.

Huge hint, when you say "and" or "also" in a patch, it's a good idea to
split it up into different commits, right?

> 
> Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
> ---
> This change is intend to replace below one:
> https://lore.kernel.org/lkml/1718629765-32720-1-git-send-email-quic_zijuhu@quicinc.com/#t

Why?  SHouldn't this be v2 instead?

>  drivers/base/devres.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 3df0025d12aa..5b1d498e83ab 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -567,6 +567,7 @@ void * devres_open_group(struct device *dev, void *id, gfp_t gfp)
>  	grp->id = grp;
>  	if (id)
>  		grp->id = id;
> +	grp->color = 0;
>  
>  	spin_lock_irqsave(&dev->devres_lock, flags);
>  	add_dr(dev, &grp->node[0]);
> @@ -1172,9 +1173,9 @@ static void devm_percpu_release(struct device *dev, void *pdata)
>  
>  static int devm_percpu_match(struct device *dev, void *data, void *p)
>  {
> -	struct devres *devr = container_of(data, struct devres, data);
> +	void __percpu *ptr = *(void __percpu **)data;
>  
> -	return *(void **)devr->data == p;
> +	return ptr == (void __percpu *)p;

What exactly is being "optimized" here?

And where did the container_of go?  You just lost all type-safeness.

thanks,

greg k-h