From nobody Wed Dec 17 17:43:19 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFE4E19D8AA; Mon, 24 Jun 2024 15:27:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719242864; cv=none; b=krTjlqwclpYTVTRCvkCbIJbO0jMK4uWJiT6EW5NVwDonxLmuF1lsadoyY30pMd+5mc+cv5XyIrn+Mo86xZ9Varlq2zn6Ka2RJCGD709T6PTctEYcDNARx6tkH973atsdA6vE4EhTFl6zdaoLmilC6QOIOZdE6e/dmFCXhHu9nHs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719242864; c=relaxed/simple; bh=OVQCYTW4L9yu0EDueyCBAY4a89Jd+rzlyMa52xLOMps=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kfLDgESflsSCW782OsRVYuYOm9xcdbLAWlNRluolMKATCQnGCe4QNBtcvZt5N9SfEKXvMbu44OtC4/899QbTgA1e/L5FQRzFpqrO3KT3UI8MC3LH7lugvtOfGwEqzBp9hENh+ovz+7eAn6q9EPi3sFwv0h42qhQvBa3pXFOKPZs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=1VW3jWei; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=aEhsb9Kv; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="1VW3jWei"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="aEhsb9Kv" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1719242859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iLt0LLfVcMa9a+gilIPNXUQswi86xUZORdJUsd8+HOo=; b=1VW3jWeiz7NTiwDQyDjfCBLU79UznLlW3fIYX2vtm/5EPNKLmO0vNAP303ZZjCc7d00Whl t5rFSOtUwFHSQ3VBewZMohJaeqH46MF5kTz6jriyA0KzYhRSdyNLS2JmOoxnUDACoV1MQZ jVcaE7bj3DHkq5BTMKg3HI7HI5XtMNPdqEv3cT6opKux/bh9VjcgTgsfHZjHsYQ5XopVrT /HJN+rd3WwsAXJDJB3qG3h+Pv/q2A0UUzd4g3dUVtxJBKuIzQl3c1mKluSIulqE8xKaoBd 7pb0X8a0TPUOvS2+fa4B6vqS9esmI4Vpit1Er+V8hab/UeUlMOl+2BtFzaO+cA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1719242859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iLt0LLfVcMa9a+gilIPNXUQswi86xUZORdJUsd8+HOo=; b=aEhsb9Kv+WZm8yWFi3PZ0NpKtcEJYhzfgkt2ZKfFfYinb3Y7eltunTYTGvDt6THjXA2/+2 elJFV18Ha+WgPDBg== To: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Daniel Bristot de Oliveira , Frederic Weisbecker , Ian Rogers , Ingo Molnar , Jiri Olsa , Kan Liang , Marco Elver , Mark Rutland , Namhyung Kim , Peter Zijlstra , Thomas Gleixner , Sebastian Andrzej Siewior , Arnaldo Carvalho de Melo Subject: [PATCH v4 6/6] perf: Split __perf_pending_irq() out of perf_pending_irq() Date: Mon, 24 Jun 2024 17:15:19 +0200 Message-ID: <20240624152732.1231678-7-bigeasy@linutronix.de> In-Reply-To: <20240624152732.1231678-1-bigeasy@linutronix.de> References: <20240624152732.1231678-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" perf_pending_irq() invokes perf_event_wakeup() and __perf_pending_irq(). The former is in charge of waking any tasks which wait to be woken up while the latter disables perf-events. The irq_work perf_pending_irq(), while this an irq_work, the callback is invoked in thread context on PREEMPT_RT. This is needed because all the waking functions (wake_up_all(), kill_fasync()) acquire sleep locks which must not be used with disabled interrupts. Disabling events, as done by __perf_pending_irq(), expects a hardirq context and disabled interrupts. This requirement is not fulfilled on PREEMPT_RT. Split functionality based on perf_event::pending_disable into irq_work named `pending_disable_irq' and invoke it in hardirq context on PREEMPT_RT. Rename the split out callback to perf_pending_disable(). Tested-by: Marco Elver Tested-by: Arnaldo Carvalho de Melo Reported-by: Arnaldo Carvalho de Melo Signed-off-by: Sebastian Andrzej Siewior --- include/linux/perf_event.h | 1 + kernel/events/core.c | 31 +++++++++++++++++++++++-------- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 99a7ea1d29ed5..65ece0d5b4b6d 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -783,6 +783,7 @@ struct perf_event { unsigned int pending_disable; unsigned long pending_addr; /* SIGTRAP */ struct irq_work pending_irq; + struct irq_work pending_disable_irq; struct callback_head pending_task; unsigned int pending_work; struct rcuwait pending_work_wait; diff --git a/kernel/events/core.c b/kernel/events/core.c index f75aa9f14c979..8bba63ea9c686 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2451,7 +2451,7 @@ static void __perf_event_disable(struct perf_event *e= vent, * hold the top-level event's child_mutex, so any descendant that * goes to exit will block in perf_event_exit_event(). * - * When called from perf_pending_irq it's OK because event->ctx + * When called from perf_pending_disable it's OK because event->ctx * is the current context on this CPU and preemption is disabled, * hence we can't get into perf_event_task_sched_out for this context. */ @@ -2491,7 +2491,7 @@ EXPORT_SYMBOL_GPL(perf_event_disable); void perf_event_disable_inatomic(struct perf_event *event) { event->pending_disable =3D 1; - irq_work_queue(&event->pending_irq); + irq_work_queue(&event->pending_disable_irq); } =20 #define MAX_INTERRUPTS (~0ULL) @@ -5218,6 +5218,7 @@ static void perf_pending_task_sync(struct perf_event = *event) static void _free_event(struct perf_event *event) { irq_work_sync(&event->pending_irq); + irq_work_sync(&event->pending_disable_irq); perf_pending_task_sync(event); =20 unaccount_event(event); @@ -6760,7 +6761,7 @@ static void perf_sigtrap(struct perf_event *event) /* * Deliver the pending work in-event-context or follow the context. */ -static void __perf_pending_irq(struct perf_event *event) +static void __perf_pending_disable(struct perf_event *event) { int cpu =3D READ_ONCE(event->oncpu); =20 @@ -6798,11 +6799,26 @@ static void __perf_pending_irq(struct perf_event *e= vent) * irq_work_queue(); // FAILS * * irq_work_run() - * perf_pending_irq() + * perf_pending_disable() * * But the event runs on CPU-B and wants disabling there. */ - irq_work_queue_on(&event->pending_irq, cpu); + irq_work_queue_on(&event->pending_disable_irq, cpu); +} + +static void perf_pending_disable(struct irq_work *entry) +{ + struct perf_event *event =3D container_of(entry, struct perf_event, pendi= ng_disable_irq); + int rctx; + + /* + * If we 'fail' here, that's OK, it means recursion is already disabled + * and we won't recurse 'further'. + */ + rctx =3D perf_swevent_get_recursion_context(); + __perf_pending_disable(event); + if (rctx >=3D 0) + perf_swevent_put_recursion_context(rctx); } =20 static void perf_pending_irq(struct irq_work *entry) @@ -6825,8 +6841,6 @@ static void perf_pending_irq(struct irq_work *entry) perf_event_wakeup(event); } =20 - __perf_pending_irq(event); - if (rctx >=3D 0) perf_swevent_put_recursion_context(rctx); } @@ -9734,7 +9748,7 @@ static int __perf_event_overflow(struct perf_event *e= vent, * is processed. */ if (in_nmi()) - irq_work_queue(&event->pending_irq); + irq_work_queue(&event->pending_disable_irq); =20 } else if (event->attr.exclude_kernel && valid_sample) { /* @@ -11972,6 +11986,7 @@ perf_event_alloc(struct perf_event_attr *attr, int = cpu, =20 init_waitqueue_head(&event->waitq); init_irq_work(&event->pending_irq, perf_pending_irq); + event->pending_disable_irq =3D IRQ_WORK_INIT_HARD(perf_pending_disable); init_task_work(&event->pending_task, perf_pending_task); rcuwait_init(&event->pending_work_wait); =20 --=20 2.45.2