From nobody Tue Feb 10 17:08:53 2026 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 CF92012E58; Fri, 22 Mar 2024 06:52:15 +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=1711090337; cv=none; b=IPijOGtixbef1YwP2CbYPOz9oQpVuX7Vp8K4gqFPir/zId9rHybQThEyK5c/SlrinbzqWHdpIpQSlAnVy/GavS/P7V10deyhNpM05qyqsPgSmfBflo857xq9ytBONtbnL29/KMubnQyNVkQMp0MPonG1IxjFbvhjO0JFs1KfxIM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711090337; c=relaxed/simple; bh=Hbaot7IOfbezNSwmi+D2RM/9exlbCH1lvaP6EvROjME=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MD6WCeaHsoor8pc3FgiWsEcouICEXlH4ibNdSGA5o0b5qbH9SgBGKg+pQuoLXi4B5jbbGJsmX4phw9Jz8JUMfoVek2iEjl2VWPQKuBgQMNNN/bekywFBuA42uPORVC4cfAQZqw1KJwXqbeshfVh6jHgkOVCcLaZ9HXUXCXfx4I4= 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=R/coBq4W; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Xp+iD1Gd; 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="R/coBq4W"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Xp+iD1Gd" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1711090334; 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=mViIwBzJy2LbFMx+Z7s8eLKaVOiaGkwX39mLOOJ/Zkk=; b=R/coBq4WVDanAJSympKYEkcTLEPkFfr+pUYY2xlwu+a3Evqi4jBxt1tw3RwxxgATxp7xxo 7H7rdcf2SchrIzqH744ucqN/hkEcnvQfnKWTwlW0dMswNmy8ruFOWbL62b/k8+PpR/lbjm Ne1tebYvDKELwJap0TG8dKvnDfUx6xKuTJ+SL5j+wauGLP6KUMWjC3uXsjIHyDjkhGHGHf huRgTZs0WPsUmkiVa17MiX1gqhuT/plxEEAiA2T+k2oNoe0QQNGvuyZhQGMrR1+epvMwqw bHtaHkx+Hm7bygyvRRuONcKvaVFL+v4ffH4bzsRqKc7KYR5ZLjP0jCTEROEKXg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1711090334; 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=mViIwBzJy2LbFMx+Z7s8eLKaVOiaGkwX39mLOOJ/Zkk=; b=Xp+iD1GdbQXf30FVh0tu2M6r9nb6GmCCcjyrrb22uE4CYjXHszVNWSthCNXKJ0oPu4nimP YJHWkjLADt292wDQ== To: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Ian Rogers , Ingo Molnar , Jiri Olsa , Marco Elver , Mark Rutland , Namhyung Kim , Peter Zijlstra , Thomas Gleixner , Sebastian Andrzej Siewior , Arnaldo Carvalho de Melo Subject: [PATCH v3 4/4] perf: Split __perf_pending_irq() out of perf_pending_irq() Date: Fri, 22 Mar 2024 07:48:24 +0100 Message-ID: <20240322065208.60456-5-bigeasy@linutronix.de> In-Reply-To: <20240322065208.60456-1-bigeasy@linutronix.de> References: <20240322065208.60456-1-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 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 24ac6765146c7..c1c6600541657 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; =20 diff --git a/kernel/events/core.c b/kernel/events/core.c index 5400f7ed2f98b..7266265ed8cc3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2449,7 +2449,7 @@ 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. */ @@ -2489,7 +2489,7 @@ 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) @@ -5175,6 +5175,7 @@ static void perf_addr_filters_splice(struct perf_even= t *event, static void _free_event(struct perf_event *event) { irq_work_sync(&event->pending_irq); + irq_work_sync(&event->pending_disable_irq); =20 unaccount_event(event); =20 @@ -6711,7 +6712,7 @@ 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 @@ -6749,11 +6750,26 @@ 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) @@ -6776,8 +6792,6 @@ 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); } @@ -9572,7 +9586,7 @@ 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); } else if (event->attr.exclude_kernel && valid_sample) { /* * Should not be able to return to user space without @@ -11912,6 +11926,7 @@ 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); =20 mutex_init(&event->mmap_mutex); --=20 2.43.0