From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EBDAC433FE for ; Tue, 5 Oct 2021 13:52:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E1B86120D for ; Tue, 5 Oct 2021 13:52:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236167AbhJENyX (ORCPT ); Tue, 5 Oct 2021 09:54:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:33116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235196AbhJENxW (ORCPT ); Tue, 5 Oct 2021 09:53:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E1121615E6; Tue, 5 Oct 2021 13:51:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633441892; bh=eUeU9bo79CwZcny0+JKZ8QpzagefINlaXNsT2xL8B8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G3w/tF8ogOcKqFKt+P/EkHOjrdiKs8fyhIkFdPnBOyiNvjbK278PbxeRu8txHaQRZ wLc+v9Z/jHS2dkVrEM8foAoS3vKNWrv8iOCUWpd2T9jnDFHXfkDWKkC69FvdtGjE2J cs7bxvCnHAF2oMTouNktDU8gmP8+Dy/Yki5aa28Y9RHhd24TvPpzpFMHQJTY6yELH3 Yvk05lw/6qBjpGxSdkNuQU6YvgONizzUb2B1u2oRofygeTO1L9JWVzSiBT8kcsx/gJ GJA29FAxoTgleWbgAwulct6LuVmMumXJizc2i1Ybv/H0bViXZdqGP3yfolBKkiJdMD rH2UpLTO4NatA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Anand K Mistry , Peter Zijlstra , Sasha Levin , mingo@redhat.com, acme@kernel.org, tglx@linutronix.de, bp@alien8.de, x86@kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH AUTOSEL 5.14 36/40] perf/x86: Reset destroy callback on event init failure Date: Tue, 5 Oct 2021 09:50:15 -0400 Message-Id: <20211005135020.214291-36-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211005135020.214291-1-sashal@kernel.org> References: <20211005135020.214291-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Anand K Mistry [ Upstream commit 02d029a41dc986e2d5a77ecca45803857b346829 ] perf_init_event tries multiple init callbacks and does not reset the event state between tries. When x86_pmu_event_init runs, it unconditionally sets the destroy callback to hw_perf_event_destroy. On the next init attempt after x86_pmu_event_init, in perf_try_init_event, if the pmu's capabilities includes PERF_PMU_CAP_NO_EXCLUDE, the destroy callback will be run. However, if the next init didn't set the destroy callback, hw_perf_event_destroy will be run (since the callback wasn't reset). Looking at other pmu init functions, the common pattern is to only set the destroy callback on a successful init. Resetting the callback on failure tries to replicate that pattern. This was discovered after commit f11dd0d80555 ("perf/x86/amd/ibs: Extend PERF_PMU_CAP_NO_EXCLUDE to IBS Op") when the second (and only second) run of the perf tool after a reboot results in 0 samples being generated. The extra run of hw_perf_event_destroy results in active_events having an extra decrement on each perf run. The second run has active_events == 0 and every subsequent run has active_events < 0. When active_events == 0, the NMI handler will early-out and not record any samples. Signed-off-by: Anand K Mistry Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210929170405.1.I078b98ee7727f9ae9d6df8262bad7e325e40faf0@changeid Signed-off-by: Sasha Levin --- arch/x86/events/core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 3092fbf9dbe4..98729ce89917 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2467,6 +2467,7 @@ static int x86_pmu_event_init(struct perf_event *event) if (err) { if (event->destroy) event->destroy(event); + event->destroy = NULL; } if (READ_ONCE(x86_pmu.attr_rdpmc) && -- 2.33.0