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From: Steven Rostedt <rostedt@goodmis.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	mingo@kernel.org, linux-kernel@vger.kernel.org,
	kan.liang@linux.intel.com, acme@kernel.org, mark.rutland@arm.com,
	alexander.shishkin@linux.intel.com, jolsa@redhat.com,
	namhyung@kernel.org, ak@linux.intel.com, eranian@google.com
Subject: Re: [PATCH 4/6] perf: Optimize get_recursion_context()
Date: Fri, 30 Oct 2020 19:31:24 -0400
Message-ID: <20201030193124.7a1ba64e@oasis.local.home> (raw)
In-Reply-To: <87v9erl5tx.fsf@nanos.tec.linutronix.de>

On Fri, 30 Oct 2020 23:14:18 +0100
Thomas Gleixner <tglx@linutronix.de> wrote:

> On Fri, Oct 30 2020 at 16:22, Steven Rostedt wrote:
> > As this is something that ftrace recursion also does, perhaps we should
> > move this into interrupt.h so that anyone that needs a counter can get  
> 
> Not in interrupt.h please. We should create kernel/include/ for stuff
> which really should only be available in the core kernel code.
> 

The recursion protection is needed for anything that registers a
callback to ftrace. I have patches that already basically do the same
thing (although, with branches) that I'm going to place in
include/linux/trace_recursion.h, so that there are helper functions
that ftrace callbacks can use, instead of having to implement their own
recursion protection. After fixing two bugs in the recursion protection
code, it's something that should be reused, instead of everyone making
similar mistakes.

Note, I thought that in_nmi() and friends was in interrupt.h, but is
really in preempt.h. All the values used in Peter's code is also
defined in preempt.h, so why not have something like that there?

I take back adding it to interrupt.h but have it in preempt.h, as it's
not defining anything new there.

-- Steve

  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 15:13 [PATCH 0/6] perf: Reduce stack usage (and misc bits) Peter Zijlstra
2020-10-30 15:13 ` [PATCH 1/6] perf: Reduce stack usage of perf_output_begin() Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-30 15:13 ` [PATCH 2/6] perf/x86: Reduce stack usage for x86_pmu::drain_pebs() Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-30 15:13 ` [PATCH 3/6] perf: Fix get_recursion_context() Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-30 15:13 ` [PATCH 4/6] perf: Optimize get_recursion_context() Peter Zijlstra
2020-10-30 17:11   ` Jesper Dangaard Brouer
2020-10-30 20:22     ` Steven Rostedt
2020-10-30 22:14       ` Thomas Gleixner
2020-10-30 23:31         ` Steven Rostedt [this message]
2020-10-31 11:23           ` Peter Zijlstra
2020-10-30 23:01       ` Peter Zijlstra
2020-10-31 12:11         ` David Laight
2020-10-31 13:18           ` David Laight
2020-11-09 12:12           ` Peter Zijlstra
2020-11-09 14:14             ` David Laight
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-30 15:13 ` [PATCH 5/6] perf/arch: Remove perf_sample_data::regs_user_copy Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra
2020-10-30 15:13 ` [PATCH 6/6] perf/x86: Make dummy_iregs static Peter Zijlstra
2020-11-10 12:45   ` [tip: perf/urgent] " tip-bot2 for Peter Zijlstra

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