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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 4487DC4CECE for ; Mon, 14 Oct 2019 17:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29B4A21A49 for ; Mon, 14 Oct 2019 17:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388277AbfJNRTd (ORCPT ); Mon, 14 Oct 2019 13:19:33 -0400 Received: from foss.arm.com ([217.140.110.172]:49600 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387802AbfJNRTd (ORCPT ); Mon, 14 Oct 2019 13:19:33 -0400 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 DBE4A1576; Mon, 14 Oct 2019 10:19:32 -0700 (PDT) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F3DDD3F6C4; Mon, 14 Oct 2019 10:19:31 -0700 (PDT) From: James Morse To: linux-edac@vger.kernel.org Cc: Mauro Carvalho Chehab , Borislav Petkov , Tony Luck , Robert Richter , John Garry Subject: [PATCH 2/2] EDAC, ghes: Reference count GHES users of ghes_edac Date: Mon, 14 Oct 2019 18:19:19 +0100 Message-Id: <20191014171919.85044-3-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191014171919.85044-1-james.morse@arm.com> References: <20191014171919.85044-1-james.morse@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-edac-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org ghes_edac only does work for the first GHES entry that registers it. The same is true for unregister: first come first served. This lack of symmetry is problematic if we have more than one GHES entry, as ghes_edac_register() can only be called once, nothing decrements ghes_init. Doing the unregister work on the first call is unsafe, as another CPU may be processing a notification in ghes_edac_report_mem_error(), using the memory we are about to free. ghes_init is already half of the reference counting. We only need to do the register work for the first call, and the unregister work for the last. Add the unregister check. This means we no longer free ghes_edac's memory while there are GHES entries that may receive a notification. Signed-off-by: James Morse Fixes: 0fe5f281f749 ("EDAC, ghes: Model a single, logical memory controller") --- drivers/edac/ghes_edac.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c index 955b59b6aade..0bb62857ffb2 100644 --- a/drivers/edac/ghes_edac.c +++ b/drivers/edac/ghes_edac.c @@ -553,6 +553,9 @@ void ghes_edac_unregister(struct ghes *ghes) if (!ghes_pvt) return; + if (atomic_dec_return(&ghes_init)) + return; + mci = ghes_pvt->mci; ghes_pvt = NULL; edac_mc_del_mc(mci->pdev); -- 2.20.1