Received-SPF: pass (google.com: domain of linux-kernel+bounces-138813-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Date: Wed, 10 Apr 2024 16:50:13 +0200
From: Frederic Weisbecker <frederic@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ian Rogers <irogers@google.com>, Ingo Molnar <mingo@redhat.com>,
	Jiri Olsa <jolsa@kernel.org>, Marco Elver <elver@google.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH v3 2/4] perf: Enqueue SIGTRAP always via task_work.
Message-ID: <ZhanJYjJQqrqYlg-@localhost.localdomain>
References: <ZhRhn1B0rMSNv6mV@pavilion.home>
 <20240409085732.FBItbOSO@linutronix.de>
 <ZhU2YwettB6i6AMp@localhost.localdomain>
 <20240409134729.JpcBYOsK@linutronix.de>
 <ZhZ54XAcBt50WEnE@localhost.localdomain>
 <20240410134702.dcWYciZB@linutronix.de>
 <ZhabcanCbQej1azv@localhost.localdomain>
 <20240410140633.0MHBLpMI@linutronix.de>
 <ZhalcBcd3w0w2HD_@localhost.localdomain>
 <20240410144821.bVdBdVOR@linutronix.de>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20240410144821.bVdBdVOR@linutronix.de>

Le Wed, Apr 10, 2024 at 04:48:21PM +0200, Sebastian Andrzej Siewior a ?crit :
> On 2024-04-10 16:42:56 [+0200], Frederic Weisbecker wrote:
> > > > Like this then?
> > > > 
> > > > https://lore.kernel.org/all/202403310406.TPrIela8-lkp@intel.com/T/#m63c28147d8ac06b21c64d7784d49f892e06c0e50
> > > 
> > > Kind of, yes. Do we have more than one waiter? If not, maybe that
> > > rcuwait would work then.
> > 
> > Indeed there is only one waiter so that should work. Would
> > that be something you can call while preemption is disabled?
> 
> rcuwait_wake_up() does only wake_up_process() which is fine.
> wake_up() does spin_lock_irqsave() which is a no.

Duh!

> On the other hand that preempt-disable needs to go anyway due to
> perf_sigtrap(). But a slim wake is a slim wake ;)

Sure thing :)

> > Thanks.
> 
> Sebastian