From mboxrd@z Thu Jan  1 00:00:00 1970
From: clabbe@baylibre.com (LABBE Corentin)
Date: Thu, 15 Nov 2018 10:30:34 +0100
Subject: [PATCH v3 0/7] include: add
 setbits32/clrbits32/clrsetbits32/setbits64/clrbits64/clrsetbits64
In-Reply-To: <20181024085700.GR30658@n2100.armlinux.org.uk>
References: <1540366553-18541-1-git-send-email-clabbe@baylibre.com>
 <20181024085700.GR30658@n2100.armlinux.org.uk>
Message-ID: <20181115093034.GB23965@Red>
To: linus-amlogic@lists.infradead.org
List-Id: linus-amlogic.lists.infradead.org

On Wed, Oct 24, 2018 at 09:57:00AM +0100, Russell King - ARM Linux wrote:
> On Wed, Oct 24, 2018 at 07:35:46AM +0000, Corentin Labbe wrote:
> > This patchset adds a new set of functions which are open-coded in lot of
> > place.
> > Basicly the pattern is always the same, "read, modify a bit, write"
> > some driver and the powerpc arch already have thoses pattern them as functions. (like ahci_sunxi.c or dwmac-meson8b)
> 
> The advantage of them being open-coded is that it's _obvious_ to the
> reviewer that there is a read-modify-write going on which, in a multi-
> threaded environment, may need some locking (so it should trigger a
> review of the locking around that code.)
> 
> With it hidden inside a helper which has no locking itself, it becomes
> much easier to pass over in review, which means that races are much
> more likely to go unspotted - and that is bad news.
> 

Hello

I understand your fear, but I think the benefit overhaul thoses.
Furthermore, drivers which I have converted does not need such locking.

If you want I can rename the header to linux/setbits-non-atomic.h for making obvious the lack of locking.

Regards