linux-kernel - Re: [PATCH v3] staging: r8188eu: Use kzalloc() with GFP

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Date:   Fri, 05 Nov 2021 17:05:25 +0100
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

On Friday, November 5, 2021 4:36:33 PM CET Dan Carpenter wrote:
> Oh yeah, you're right.  It never *just* does spinlocks (as stated in the
> commit message btw), it does spin_lock_bh() which bumps the soft IRQ
> count.

Thank you very much for checking and confirming.

> > To summarize, I think that using in_interrupt() in the old wrappers was 
the 
> > wiser choice.
> 
> "Wiser" is not the right word.  The wrappers were always stupid, but I
> guess they did work in this case so the fixes tag is correct.

Ah, sorry. I was not able to express my thought properly :(

I agree with you that the wrappers were a not a good idea and Larry did well 
in removing them. Furthermore, I think that delegating the choice to use 
GFP_KERNEL vs. GFP_ATOMIC depending on the return from in_interrupt() is very 
bad design and it adds sensible overhead. 

I used "wiser" is a stricter sense. I meant that, if wrappers were needed 
(but they were not), in_interrupt() is "wiser" than "in_atomic()".

Regards,

Fabio M. De Francesco