From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 961713A599D for ; Tue, 12 May 2026 14:03:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778594602; cv=none; b=KjlesyL2FS1ORTZFfxOwwVCKEwEDXlscWYSSVT05ciCUVWoTl0I05kDSC4HPHkOuzczjWc/hlWgQEKbER9MPf2DL5hpkus6YldjehkfmqAQdeOClMnbDgvAaKGsQtz84v0Bt5BQAWD7EhI76kCaMMmy/I/9zII0Gvd5Cj82R9D0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778594602; c=relaxed/simple; bh=N1apW1tBvb0a/mnB0ObiEYuE3Fuc0xbXMl1UEGlCu8I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=kNIpG6JIKcoULFmpFYCNSabAmQVIqlJa5+9k9uM/CPlmT2ir8aIuvFRohrSP0qamLPfjicfPHfkPUlqphQ3WN8MRsec95+d3k6FqzzugldfFet7ZXVnowkrdL7L/v1tahFvvG99jtaR477joVtZ2nmsvFyZ13S5Vpk3cRf+Aq2w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=iBZni/NJ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iBZni/NJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1778594598; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=owPVbqfN1q1NzH+2NJbTR29TZuwOEggaR1L0dz2AxsQ=; b=iBZni/NJUMQ5cvLYOhCq5zUPWzqTaRf+p8uLois4HXudkaTAOx0K6ZbOuuyDJtybwwuPf+ dm7fLMDtWBMvcVkZNI5bse+GzfJHfACWLNvhOhX+E30pyQo8SN8tPIRTeE4a3RaUfMv7UI vqF3JXtF0mP8aDpsuGDmPNjwynTiFpE= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-449-n4iYhkE4MF65Po6Md3w9rA-1; Tue, 12 May 2026 10:03:12 -0400 X-MC-Unique: n4iYhkE4MF65Po6Md3w9rA-1 X-Mimecast-MFC-AGG-ID: n4iYhkE4MF65Po6Md3w9rA_1778594590 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 74F951800367; Tue, 12 May 2026 14:03:10 +0000 (UTC) Received: from gmonaco-thinkpadt14gen3.rmtit.csb (unknown [10.44.34.139]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E62AC180058F; Tue, 12 May 2026 14:03:07 +0000 (UTC) From: Gabriele Monaco To: linux-kernel@vger.kernel.org, Steven Rostedt , Gabriele Monaco , linux-trace-kernel@vger.kernel.org Cc: Nam Cao , Wen Yang Subject: [PATCH 4/9] rv: Prevent task migration while handling per-CPU events Date: Tue, 12 May 2026 16:02:45 +0200 Message-ID: <20260512140250.262190-5-gmonaco@redhat.com> In-Reply-To: <20260512140250.262190-1-gmonaco@redhat.com> References: <20260512140250.262190-1-gmonaco@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: D5ztaW45W691vfP-ne_RDR_RkCHQ0oGdHcGgxecM6yM_1778594590 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true Tracepoint handlers are now fully preemptible. When a per-CPU monitor handles an event, it retrieves the monitor state using a per-CPU pointer. If the event itself doesn't disable preemption, the task can migrate to a different CPU and we risk updating the wrong monitor. Mitigate this by explicitly disabling task migration before acquiring the monitor pointer. This cannot guarantee the monitor runs on the correct CPU but reduces the race condition window and prevents warnings. Signed-off-by: Gabriele Monaco --- include/rv/da_monitor.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h index 0b7028df08fb..a9fd284195ee 100644 --- a/include/rv/da_monitor.h +++ b/include/rv/da_monitor.h @@ -181,6 +181,10 @@ static inline void da_monitor_destroy(void) da_monitor_reset_all(); } +#ifndef da_implicit_guard +#define da_implicit_guard() +#endif + #elif RV_MON_TYPE == RV_MON_PER_CPU /* * Functions to define, init and get a per-cpu monitor. @@ -230,6 +234,10 @@ static inline void da_monitor_destroy(void) da_monitor_reset_all(); } +#ifndef da_implicit_guard +#define da_implicit_guard() guard(migrate)() +#endif + #elif RV_MON_TYPE == RV_MON_PER_TASK /* * Functions to define, init and get a per-task monitor. @@ -677,6 +685,7 @@ static inline bool __da_handle_start_run_event(struct da_monitor *da_mon, */ static inline void da_handle_event(enum events event) { + da_implicit_guard(); __da_handle_event(da_get_monitor(), event, 0); } @@ -692,6 +701,7 @@ static inline void da_handle_event(enum events event) */ static inline bool da_handle_start_event(enum events event) { + da_implicit_guard(); return __da_handle_start_event(da_get_monitor(), event, 0); } @@ -703,6 +713,7 @@ static inline bool da_handle_start_event(enum events event) */ static inline bool da_handle_start_run_event(enum events event) { + da_implicit_guard(); return __da_handle_start_run_event(da_get_monitor(), event, 0); } -- 2.54.0