From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Alexander Potapenko <glider@google.com>
Subject: Re: [RFC patch 00/41] stacktrace: Avoid the pointless redirection through struct stack_trace
Date: Wed, 10 Apr 2019 13:49:47 +0200 [thread overview]
Message-ID: <20190410114947.GA11158@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190410102754.387743324@linutronix.de>
On Wed, Apr 10, 2019 at 12:27:54PM +0200, Thomas Gleixner wrote:
> Struct stack_trace is a sinkhole for input and output parameters which is
> largely pointless for most usage sites. In fact if embedded into other data
> structures it creates indirections and extra storage overhead for no benefit.
>
> Looking at all usage sites makes it clear that they just require an
> interface which is based on a storage array. That array is either on stack,
> global or embedded into some other data structure.
>
> Some of the stack depot usage sites are outright wrong, but fortunately the
> wrongness just causes more stack being used for nothing and does not have
> functional impact.
>
> Another oddity is the inconsistent termination of the stack trace with
> ULONG_MAX. It's pointless as the number of entries is what determines the
> length of the stored trace. In fact quite some call sites remove the
> ULONG_MAX marker afterwards with or without nasty comments about it. Not
> all architectures do that and those which do, do it inconsistenly either
> conditional on nr_entries == 0 or unconditionally.
>
> The following series cleans that up by:
>
> 1) Removing the ULONG_MAX termination in the architecture code
>
> 2) Removing the ULONG_MAX fixups at the call sites
>
> 3) Providing plain storage array based interfaces for stacktrace and
> stackdepot.
>
> 4) Cleaning up the mess at the callsites including some related
> cleanups.
>
> 5) Removing the struct stack_trace based interfaces
>
> This is not changing the struct stack_trace interfaces at the architecture
> level, but it removes the exposure to the generic code.
>
> It's only lightly tested as I'm traveling and access to my test boxes is
> limited.
This is indeed a much needed cleanup; thanks for starting this.
I didn't spot anything wrong while reading through it, so:
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
prev parent reply other threads:[~2019-04-10 11:50 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 10:27 [RFC patch 00/41] stacktrace: Avoid the pointless redirection through struct stack_trace Thomas Gleixner
2019-04-10 10:27 ` [RFC patch 01/41] um/stacktrace: Remove the pointless ULONG_MAX marker Thomas Gleixner
2019-04-14 20:34 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:27 ` [RFC patch 02/41] x86/stacktrace: " Thomas Gleixner
2019-04-14 20:34 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:27 ` [RFC patch 03/41] arm/stacktrace: " Thomas Gleixner
2019-04-14 20:35 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:27 ` [RFC patch 04/41] sh/stacktrace: " Thomas Gleixner
2019-04-14 20:36 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:27 ` [RFC patch 05/41] unicore32/stacktrace: " Thomas Gleixner
2019-04-14 20:36 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 06/41] riscv/stacktrace: " Thomas Gleixner
2019-04-14 20:37 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 07/41] arm64/stacktrace: " Thomas Gleixner
2019-04-14 20:38 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 08/41] parisc/stacktrace: " Thomas Gleixner
2019-04-14 20:38 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 09/41] s390/stacktrace: " Thomas Gleixner
2019-04-14 20:39 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 10/41] lockdep: Remove the ULONG_MAX stack trace hackery Thomas Gleixner
2019-04-14 20:40 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 11/41] mm/slub: " Thomas Gleixner
2019-04-14 20:40 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 12/41] mm/page_owner: " Thomas Gleixner
2019-04-14 20:41 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 13/41] mm/kasan: " Thomas Gleixner
2019-04-10 11:31 ` Dmitry Vyukov
2019-04-14 20:42 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 14/41] latency_top: " Thomas Gleixner
2019-04-14 20:42 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 15/41] drm: " Thomas Gleixner
2019-04-14 20:43 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 16/41] tracing: " Thomas Gleixner
2019-04-11 2:34 ` Josh Poimboeuf
2019-04-11 3:07 ` Steven Rostedt
2019-04-14 20:44 ` [tip:core/stacktrace] " tip-bot for Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 17/41] tracing: Make stack_trace_print() static and rename it Thomas Gleixner
2019-04-10 12:47 ` Steven Rostedt
2019-04-11 0:19 ` AKASHI Takahiro
2019-04-10 10:28 ` [RFC patch 18/41] stacktrace: Provide helpers for common stack trace operations Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 19/41] lib/stackdepot: Provide functions which operate on plain storage arrays Thomas Gleixner
2019-04-10 13:39 ` Alexander Potapenko
2019-04-10 10:28 ` [RFC patch 20/41] backtrace-test: Simplify stack trace handling Thomas Gleixner
2019-04-11 2:47 ` Josh Poimboeuf
2019-04-10 10:28 ` [RFC patch 21/41] proc: Simplify task stack retrieval Thomas Gleixner
2019-04-14 14:49 ` Alexey Dobriyan
2019-04-10 10:28 ` [RFC patch 22/41] latency_top: Simplify stack trace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 23/41] mm/slub: Simplify stack trace retrieval Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 24/41] mm/kmemleak: Simplify stacktrace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 25/41] mm/kasan: " Thomas Gleixner
2019-04-10 11:33 ` Dmitry Vyukov
2019-04-11 2:55 ` Josh Poimboeuf
2019-04-14 16:54 ` Thomas Gleixner
2019-04-14 17:00 ` Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 26/41] mm/page_owner: Simplify stack trace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 27/41] fault-inject: Simplify stacktrace retrieval Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 28/41] dma/debug: Simplify stracktrace retrieval Thomas Gleixner
2019-04-10 11:08 ` Christoph Hellwig
2019-04-10 12:08 ` Thomas Gleixner
2019-04-10 12:25 ` Steven Rostedt
2019-04-11 17:21 ` Christoph Hellwig
2019-04-11 17:36 ` Steven Rostedt
2019-04-11 17:44 ` Christoph Hellwig
2019-04-11 3:02 ` Josh Poimboeuf
2019-04-11 3:09 ` Steven Rostedt
2019-04-10 10:28 ` [RFC patch 29/41] btrfs: ref-verify: Simplify stack trace retrieval Thomas Gleixner
2019-04-10 11:31 ` Johannes Thumshirn
2019-04-10 12:05 ` Thomas Gleixner
2019-04-10 12:38 ` Johannes Thumshirn
2019-04-10 12:50 ` David Sterba
2019-04-10 13:47 ` Alexander Potapenko
2019-04-10 10:28 ` [RFC patch 30/41] dm bufio: " Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 31/41] dm persistent data: Simplify stack trace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 32/41] drm: Simplify stacktrace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 33/41] lockdep: Remove unused trace argument from print_circular_bug() Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 34/41] lockdep: Move stack trace logic into check_prev_add() Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 35/41] lockdep: Simplify stack trace handling Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 36/41] tracing: Simplify stacktrace retrieval in histograms Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 37/41] tracing: Use percpu stack trace buffer more intelligently Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 38/41] tracing: Make ftrace_trace_userstack() static and conditional Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 39/41] tracing: Simplify stack trace retrieval Thomas Gleixner
2019-04-10 10:28 ` [RFC patch 40/41] stacktrace: Remove obsolete functions Thomas Gleixner
2019-04-11 3:33 ` Josh Poimboeuf
2019-04-11 9:13 ` Peter Zijlstra
2019-04-11 13:00 ` Josh Poimboeuf
2019-04-10 10:28 ` [RFC patch 41/41] lib/stackdepot: " Thomas Gleixner
2019-04-10 13:49 ` Alexander Potapenko
2019-04-10 11:49 ` Peter Zijlstra [this message]
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