From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook
Date: Tue, 11 Feb 2020 16:29:45 +0100 [thread overview]
Message-ID: <20200211152945.GW14946@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200211150532.GU14914@hirez.programming.kicks-ass.net>
On Tue, Feb 11, 2020 at 04:05:32PM +0100, Peter Zijlstra wrote:
> So we haz:
>
> | #define nmi_enter() \
> | do { \
> | arch_nmi_enter(); \
>
> arm64 only, lets ignore for now
>
> | printk_nmi_enter(); \
>
> notrace
>
> | lockdep_off(); \
>
> notrace
>
> | ftrace_nmi_enter(); \
>
> !notrace !!!
>
> | BUG_ON(in_nmi()); \
> | preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET);\
>
> lets make this __preempt_count_add() ASAP !
preempt_count_add() first frobs the actual preempt_count and then does
the trace, so that might just work. But it does need a notrace
annotation, I'm thinking, because calling into the function tracer
_before_ we do the preempt_count increment is irrecoverable crap.
> | rcu_nmi_enter(); \
>
> are you _really_ sure you want to go trace that ?!?
>
> | trace_hardirq_enter(); \
> | } while (0)
>
>
next prev parent reply other threads:[~2020-02-11 15:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 22:06 [PATCH] tracing/perf: Move rcu_irq_enter/exit_irqson() to perf trace point hook Steven Rostedt
2020-02-11 0:30 ` Mathieu Desnoyers
2020-02-11 2:22 ` Steven Rostedt
2020-02-11 2:32 ` joel
2020-02-11 15:19 ` Mathieu Desnoyers
2020-02-11 12:00 ` Peter Zijlstra
2020-02-11 13:03 ` Paul E. McKenney
2020-02-11 13:16 ` Peter Zijlstra
2020-02-11 13:23 ` Paul E. McKenney
2020-02-11 14:10 ` Steven Rostedt
2020-02-11 11:49 ` Peter Zijlstra
2020-02-11 12:59 ` Paul E. McKenney
2020-02-11 13:10 ` Peter Zijlstra
2020-02-11 13:20 ` Paul E. McKenney
2020-02-11 14:05 ` Steven Rostedt
2020-02-11 15:05 ` Peter Zijlstra
2020-02-11 15:29 ` Peter Zijlstra [this message]
2020-02-11 16:16 ` Steven Rostedt
2020-02-11 15:06 ` Paul E. McKenney
2020-02-11 15:31 ` Peter Zijlstra
2020-02-11 15:40 ` Paul E. McKenney
2020-02-11 12:21 ` Peter Zijlstra
2020-02-11 14:10 ` Steven Rostedt
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