From nobody Sat Sep 26 08:05:38 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6EE8C403EA1; Thu, 3 Sep 2026 09:35:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788428134; cv=none; b=PO0OQgkBHRjQgMstDfdlyAJPsu7Mxkq6blSwDhrjYjONOJB5GBiiRNyns7tYeBhrbZsLoYIszoA31Lxvrhp1rUWgXIsEHpQnyclyRyv313C+T6G7kF9rjaNP+uMNN0ddku5ISpyvWJFWf4Clmn/uJ8TAefvwWv8/ukHUah9yGDE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788428134; c=relaxed/simple; bh=P/gApI/jTGDCX/7W6Htuiuu7577T7jl7mGMwxwH5xcM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=Rn2aSTcSczOvHDrF/jBxFVAkQn4/mefmOGtwbZ80k1SzZWw/DKpYUf20+z7tjr3+kNm6C4Kkf+HzbdSh3uAtJRlyvbTqiD4QLBUdsLImbAcGuaHvbG3ws46B6HwUR/C01ECord5V4lBpUb89tB5wFuht32WwN8bLxHhyCzLW51k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=CWSreIME; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="CWSreIME" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 403A21596; Thu, 3 Sep 2026 02:35:27 -0700 (PDT) Received: from e132581.arm.com (unknown [10.2.196.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 385E53F7D8; Thu, 3 Sep 2026 02:35:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788428131; bh=P/gApI/jTGDCX/7W6Htuiuu7577T7jl7mGMwxwH5xcM=; h=From:Date:Subject:To:Cc:From; b=CWSreIMEuFcfa6KgwoQQVDfM2rqzA3Nh7LUthlB3EX5gpnkxeOtdAcwmyYoLg8dSt 2fUOOvFRcyO/sCsoq7blJRu88dRyDP8ZL7LANuEiIJAWIyPztrzAjEHMyx8Nw+eZth ClGbEgo7p+ujAWKvADMzUB/oW5iB/2HrsF7YzrYc= From: Leo Yan Date: Thu, 03 Sep 2026 10:35:12 +0100 Subject: [PATCH] perf/core: Fix ITRACE start suppression for inherited events Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260903-perf_core_itrace_start_fix_inherit_event-v1-1-6bff7e675af5@arm.com> X-B4-Tracking: v=1; b=H4sIAE8/mWoC/x2N0QqDMAwAf0XyvEJXQc1+ZYxQapx5qZIGEcR/X 9jjwXF3QWMVbvDqLlA+pMlWHZ6PDsqa65eDzM6QYhoixj7srAuVTZnENBemZlmNFjlJ6uoxIz6 4WsgT9nEeMU2I4Lld2aX/6v257x8C9B6wegAAAA== X-Change-ID: 20260903-perf_core_itrace_start_fix_inherit_event-a8930d792899 To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark Cc: Ingo Molnar , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Sashiko AI , Leo Yan X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1788428129; l=1944; i=leo.yan@arm.com; s=20250604; h=from:subject:message-id; bh=P/gApI/jTGDCX/7W6Htuiuu7577T7jl7mGMwxwH5xcM=; b=7AToI7D2MoDKTHUcW/Lhn7qNF5k4sJ/nXZCHpXwQZrQNqrvnaxX0R3eTorRoSMLVuIqQBl1oe 4Tk9aZEOiWTBUNOQEqvf7bB51kd3G5OWnFAaoVlQCbHsWnELWQv7v0q X-Developer-Key: i=leo.yan@arm.com; a=ed25519; pk=k4BaDbvkCXzBFA7Nw184KHGP5thju8lKqJYIrOWxDhI= PMU drivers call perf_event_itrace_started() for the event that has started tracing. This sets PERF_ATTACH_ITRACE in that event's attach_state. For inherited events, however, perf_log_itrace_start() replaces the child event with its parent before checking PERF_ATTACH_ITRACE. The setter and checker therefore operate on different events. If the parent's flag is clear, the child continues to emit ITRACE_START records on subsequent schedule-ins. If the parent has already started, its flag can instead suppress the child's initial record. Remove the parent substitution so that perf_log_itrace_start() checks the same event that the PMU driver marks as started. This is safe for tool consumers. Intel PT uses the ITRACE_START record to set the current thread context. CoreSight ETM uses the record only to find or create the corresponding thread. Neither decoder depends on the parent event. Reported-by: Sashiko AI Closes: https://lore.kernel.org/linux-perf-users/20260901164705.042781F000E= 9@smtp.kernel.org/ Fixes: 9a6694cfa239 ("perf/x86/intel/pt: Do not force sync packets on every= schedule-in") Signed-off-by: Leo Yan --- kernel/events/core.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index a6c8e38a311042afab6b65814a84c67b87ba929b..991ae214d46ebe8b0d9de497255= f25a4ad12397f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10572,9 +10572,6 @@ static void perf_log_itrace_start(struct perf_event= *event) } rec; int ret; =20 - if (event->parent) - event =3D event->parent; - if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) || event->attach_state & PERF_ATTACH_ITRACE) return; --- base-commit: 940de590b839f71d6dc846160534bf202401b8b7 change-id: 20260903-perf_core_itrace_start_fix_inherit_event-a8930d792899 Best regards, --=20 Leo Yan