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From: Dmitry Ilvokhin <d@ilvokhin.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	Christoph Lameter <cl@gentwo.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Boqun Feng <boqun@kernel.org>, Waiman Long <longman@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, kernel-team@meta.com
Subject: Re: [PATCH RFC 3/3] locking: Wire up contended_release tracepoint
Date: Tue, 10 Mar 2026 15:12:45 +0000	[thread overview]
Message-ID: <abA07Tn034C66HI2@shell.ilvokhin.com> (raw)
In-Reply-To: <20260305105924.7069eb23@gandalf.local.home>

On Thu, Mar 05, 2026 at 10:59:24AM -0500, Steven Rostedt wrote:
> On Wed,  4 Mar 2026 16:56:17 +0000
> Dmitry Ilvokhin <d@ilvokhin.com> wrote:
> 
> > @@ -204,6 +206,8 @@ static inline void rwbase_write_unlock(struct rwbase_rt *rwb)
> >  	unsigned long flags;
> >  
> >  	raw_spin_lock_irqsave(&rtm->wait_lock, flags);
> > +	if (rt_mutex_has_waiters(rtm))
> > +		trace_contended_release(rwb);
> 
> Hmm, if statements should never be used just for tracepoints without a
> static branch. The above should be:
> 
> 	if (trace_contended_release_enabled() && rt_mutex_has_waiters(rtm))
> 		trace_contended_release(rwb);
> 
> The above "trace_contened_release_enabled()" is a static_branch where it
> turns the if statement into a nop when the tracepoint is not enabled, and a
> jmp when it is.

Thanks for catching this, Steven. Fixed locally.


      parent reply	other threads:[~2026-03-10 15:12 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-04 16:56 [PATCH RFC 0/3] locking: contended_release tracepoint instrumentation Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 1/3] locking: Add contended_release tracepoint Dmitry Ilvokhin
2026-03-04 22:55   ` Masami Hiramatsu
2026-03-10 15:58     ` Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 2/3] locking/percpu-rwsem: Extract __percpu_up_read_slowpath() Dmitry Ilvokhin
2026-03-04 22:02   ` Peter Zijlstra
2026-03-05 15:47     ` Steven Rostedt
2026-03-05 16:05       ` Peter Zijlstra
2026-03-10 15:26     ` Dmitry Ilvokhin
2026-03-04 16:56 ` [PATCH RFC 3/3] locking: Wire up contended_release tracepoint Dmitry Ilvokhin
2026-03-05 15:59   ` Steven Rostedt
2026-03-05 17:42     ` Peter Zijlstra
2026-03-05 18:06       ` Steven Rostedt
2026-03-10 15:12     ` Dmitry Ilvokhin [this message]

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