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Date: Tue, 20 Aug 2024 21:36:13 +0800
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Miao Wang <shankerwangmiao@gmail.com>
Cc: Xi Ruoyao <xry111@xry111.site>, Huacai Chen <chenhuacai@kernel.org>,
	loongarch@lists.linux.dev, Sasha Levin <sashal@kernel.org>,
	stable@vger.kernel.org, WANG Xuerui <kernel@xen0n.name>,
	linux-api@vger.kernel.org
Subject: Re: It is correct to introduce new sys calls to stable versions?
Message-ID: <2024082057-coherence-lethargy-3513@gregkh>
References: <DF762B6F-360A-4C0C-8C85-55686417209B@gmail.com>
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In-Reply-To: <DF762B6F-360A-4C0C-8C85-55686417209B@gmail.com>

On Tue, Aug 20, 2024 at 09:19:04PM +0800, Miao Wang wrote:
> Hi, Greg
> 
> I saw you have included commit 7697a0fe0154 ("LoongArch: Define
> __ARCH_WANT_NEW_STAT in unistd.h") in your stable trees, which
> actually introduced new sys calls newfstatat and fstat to Loongarch.

See the documentation in that commit for why it was done.

> I wonder if it is correct to add new syscalls, which actually changes
> the kernel features, in stable releases, as it might confuse downstream
> developers because they may assume the existence of a certain feature
> after a certain version.

Version numbers should never be used to be checked for anything as they
are only a "moment in time" stamp.  They do not reflect features or
capabilities or anything else.

Test for functionality if you want to check for something, that's the
only way it will ever work on all of the variants of different
"enterprise" kernels.

thanks,

greg k-h