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 X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E733BC28CC5 for ; Sat, 8 Jun 2019 11:45:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA134214AF for ; Sat, 8 Jun 2019 11:45:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559994325; bh=OwCmgkkgVHwbMkcZtlSkOW75C8nLCqtITaqQy3Y+Dhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dEL0zPik9IhgC3OUME9jBoj4B5xkHRVG6+PDEs5WiBkO9B2VltDJz5PLBoIeo+V18 4YjBrKuX1VqW6XKkH4eO6cY2oGecMRHtEBzfwTpSKBPa//tE0a3PQ3OTZ0+r5NYuPc Gfyi86iF6omJbw6R9/0a2PNVsuepvNquv1VhaI4I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728691AbfFHLpZ (ORCPT ); Sat, 8 Jun 2019 07:45:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:60666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728114AbfFHLnV (ORCPT ); Sat, 8 Jun 2019 07:43:21 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6A3762168B; Sat, 8 Jun 2019 11:43:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559994200; bh=OwCmgkkgVHwbMkcZtlSkOW75C8nLCqtITaqQy3Y+Dhc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HN7AUlDBQVdIZFYbHQka0yA5eEplRzaA5JR6drvYWDFHQMwQzrE+TW+RMAiAoGqLZ 75s4Hr2en3UmVsmzMEHeDJP1V2cruApRnDMYJ6wy+RCHBXLcOltIyj9aUVX8qrPpV1 d/GFXkV3ZesyIxnnXLXJJ0njfMonyHYeho8tR6WY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Zijlstra , Yabin Cui , Alexander Shishkin , Arnaldo Carvalho de Melo , Jiri Olsa , Linus Torvalds , Stephane Eranian , Thomas Gleixner , Vince Weaver , acme@kernel.org, mark.rutland@arm.com, namhyung@kernel.org, Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 4.19 15/49] perf/ring-buffer: Always use {READ,WRITE}_ONCE() for rb->user_page data Date: Sat, 8 Jun 2019 07:41:56 -0400 Message-Id: <20190608114232.8731-15-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190608114232.8731-1-sashal@kernel.org> References: <20190608114232.8731-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra [ Upstream commit 4d839dd9e4356bbacf3eb0ab13a549b83b008c21 ] We must use {READ,WRITE}_ONCE() on rb->user_page data such that concurrent usage will see whole values. A few key sites were missing this. Suggested-by: Yabin Cui Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: acme@kernel.org Cc: mark.rutland@arm.com Cc: namhyung@kernel.org Fixes: 7b732a750477 ("perf_counter: new output ABI - part 1") Link: http://lkml.kernel.org/r/20190517115418.394192145@infradead.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/events/ring_buffer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index d32b9375ec0e..12f351b253bb 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -101,7 +101,7 @@ static void perf_output_put_handle(struct perf_output_handle *handle) * See perf_output_begin(). */ smp_wmb(); /* B, matches C */ - rb->user_page->data_head = head; + WRITE_ONCE(rb->user_page->data_head, head); /* * We must publish the head before decrementing the nest count, @@ -490,7 +490,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size) handle->aux_flags); } - rb->user_page->aux_head = rb->aux_head; + WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); if (rb_need_aux_wakeup(rb)) wakeup = true; @@ -522,7 +522,7 @@ int perf_aux_output_skip(struct perf_output_handle *handle, unsigned long size) rb->aux_head += size; - rb->user_page->aux_head = rb->aux_head; + WRITE_ONCE(rb->user_page->aux_head, rb->aux_head); if (rb_need_aux_wakeup(rb)) { perf_output_wakeup(handle); handle->wakeup = rb->aux_wakeup + rb->aux_watermark; -- 2.20.1