From: Mark Rutland <mark.rutland@arm.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Eric Dumazet <edumazet@google.com>,
Ingo Molnar <mingo@kernel.org>, Jiri Slaby <jslaby@suse.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 0/3] Kill off show_stack() NULL-implies-current idiom
Date: Tue, 27 Sep 2016 18:57:20 +0100 [thread overview]
Message-ID: <20160927175720.GA4479@remoulade> (raw)
In-Reply-To: <20160926200136.sbltg4tp5uft4yfo@treble>
On Mon, Sep 26, 2016 at 03:01:36PM -0500, Josh Poimboeuf wrote:
> On Mon, Sep 26, 2016 at 04:16:16PM +0100, Mark Rutland wrote:
> > Today, show_stack() accepts a NULL task parameter, which it takes to mean the
> > current task. However, as noted in tip/x86/asm commit:
> >
> > 81539169f283329f ("x86/dumpstack: Remove NULL task pointer convention")
> >
> > ... having a NULL task parameter imply current leads to subtle bugs in stack
> > walking code (so far seen on both 86 and arm64), makes callsites harder to
> > read, and is unnecessary as all callers have access to current.
> >
> > As a step towards removing the problematic NULL-implies-current idiom entirely,
> > these patches ensure that generic code explictly passes current to
> > show_stack(), rather than relying on arch code to handle NULL.
>
> This is a good step, though it would be really nice to fix this
> tree-wide. Do you have any plans to do so?
I started having a go, and in doing so I've realised that as things stand,
these patches are broken, as some architectures don't handle current
explicitly.
Please disregard all patches in this series.
Apologies,
Mark.
prev parent reply other threads:[~2016-09-27 17:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-26 15:16 [PATCH 0/3] Kill off show_stack() NULL-implies-current idiom Mark Rutland
2016-09-26 15:16 ` [PATCH 1/3] sched: document that show_stack() should not be passed a NULL task Mark Rutland
2016-09-26 15:16 ` [PATCH 2/3] drivers/tty: Explicitly pass current to show_stack Mark Rutland
2016-09-26 15:16 ` [PATCH 3/3] lib: dump_stack: explicitly " Mark Rutland
2016-09-26 20:01 ` [PATCH 0/3] Kill off show_stack() NULL-implies-current idiom Josh Poimboeuf
2016-09-26 21:33 ` Mark Rutland
2016-09-27 17:57 ` Mark Rutland [this message]
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