linux-kernel - Re: [regression] x86/signal/64: Fix SS handling for signals delivered to 64-bit programs breaks dosemu

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Date:	Thu, 13 Aug 2015 16:05:37 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Raymond Jennings <shentino@...il.com>
Cc:	Cyrill Gorcunov <gorcunov@...il.com>,
	Andy Lutomirski <luto@...capital.net>,
	Pavel Emelyanov <xemul@...allels.com>,
	Stas Sergeev <stsp@...t.ru>,
	Linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [regression] x86/signal/64: Fix SS handling for signals delivered
 to 64-bit programs breaks dosemu

On Thu, Aug 13, 2015 at 3:01 PM, Raymond Jennings <shentino@...il.com> wrote:
>
> So it still counts as a regression if the kernel pulls the rug out from
> under someone that was relying on undocumented or buggy behavior?

Absolutely. There are no excuses for regressions. If the code was
badly written and left itself open to user space "misusing" it, it's
our problem. Especially if the code was badly written to begin with,
and user space worked around our bad code.

We don't then "fix" code and blame user space for doing bad things.

In particular, we don't cop out and say "hey, you didn't follow the
docs" (whether they existed or not) or "you didn't do what we meant
you to do".

The _only_ thing that matters is that something broke.

             Linus
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