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 D2986C433F5 for ; Fri, 8 Oct 2021 11:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC22160F14 for ; Fri, 8 Oct 2021 11:34:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240797AbhJHLgi (ORCPT ); Fri, 8 Oct 2021 07:36:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:59432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240337AbhJHLeH (ORCPT ); Fri, 8 Oct 2021 07:34:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 57D056135E; Fri, 8 Oct 2021 11:31:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1633692686; bh=rg0SbsjwPdxuWzq7sNcvIIHg0Ur4sdDbfVSZ5CHT2u4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JKyvWfgB6lHlfibI/9aE59GmsH9W4fxuR+Nhq9gBmeYV0Bb1pIbi2nFS7oLqDUe/5 CwMgk7UrBAzTSdJzAt4S3678AEB/zAkSvvourpuvzhdbhFn8hG7I5QaFctsKFfgSRN Pz2J8eLaacjFbw9MvVCH0sN1Z8ILlapiwqEi3XYo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anand K Mistry , "Peter Zijlstra (Intel)" Subject: [PATCH 5.10 28/29] perf/x86: Reset destroy callback on event init failure Date: Fri, 8 Oct 2021 13:28:15 +0200 Message-Id: <20211008112717.915996308@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211008112716.914501436@linuxfoundation.org> References: <20211008112716.914501436@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Anand K Mistry commit 02d029a41dc986e2d5a77ecca45803857b346829 upstream. 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: Greg Kroah-Hartman --- arch/x86/events/core.c | 1 + 1 file changed, 1 insertion(+) --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2284,6 +2284,7 @@ static int x86_pmu_event_init(struct per if (err) { if (event->destroy) event->destroy(event); + event->destroy = NULL; } if (READ_ONCE(x86_pmu.attr_rdpmc) &&