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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 96CFEC43463 for ; Fri, 18 Sep 2020 02:46:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EC942075B for ; Fri, 18 Sep 2020 02:46:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600397193; bh=/SxPJUpqKhaxSW+fenMFVsuIVtuTWZGsuUoRBdV6OaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lZWUeAkRrwqxmtDA+qAY40VZzyVXIFC2s9dDj0gvQLwI7WhS3juDNl4bABJ09WhMZ r4NXU3lcovelYje21W67vjWQsDahdHU1CnVTC464MjwYNzIXvB8E8YahWz0MSChXx4 BQ/Ce29bL/3MgpUnGS38ClF+0+D7mfkYuawB+DbU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728480AbgIRCq2 (ORCPT ); Thu, 17 Sep 2020 22:46:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:33558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728338AbgIRCJx (ORCPT ); Thu, 17 Sep 2020 22:09:53 -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 92DFF2395A; Fri, 18 Sep 2020 02:09:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600394993; bh=/SxPJUpqKhaxSW+fenMFVsuIVtuTWZGsuUoRBdV6OaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0uvDsgXT6wM+g2TXUAtAk2Q32Q06OXdgdDKhxXVYAauGDatWw9KBFevwMjD/fuphJ b00wtwUfno1/U0F7DXhuioOV1ryVX5aUqvQNpiADTU/EYlhH0DeQSK1hEP8GCaQJbx 98xfN8e/A9zn5E41BgY/vHTH7Qy1r+OxGFp/Xn8M= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: James Morse , Catalin Marinas , Sasha Levin Subject: [PATCH AUTOSEL 4.19 091/206] firmware: arm_sdei: Use cpus_read_lock() to avoid races with cpuhp Date: Thu, 17 Sep 2020 22:06:07 -0400 Message-Id: <20200918020802.2065198-91-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020802.2065198-1-sashal@kernel.org> References: <20200918020802.2065198-1-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: James Morse [ Upstream commit 54f529a6806c9710947a4f2cdc15d6ea54121ccd ] SDEI has private events that need registering and enabling on each CPU. CPUs can come and go while we are trying to do this. SDEI tries to avoid these problems by setting the reregister flag before the register call, so any CPUs that come online register the event too. Sticking plaster like this doesn't work, as if the register call fails, a CPU that subsequently comes online will register the event before reregister is cleared. Take cpus_read_lock() around the register and enable calls. We don't want surprise CPUs to do the wrong thing if they race with these calls failing. Signed-off-by: James Morse Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- drivers/firmware/arm_sdei.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c index 05b528c7ed8fd..e809f4d9a9e93 100644 --- a/drivers/firmware/arm_sdei.c +++ b/drivers/firmware/arm_sdei.c @@ -410,14 +410,19 @@ int sdei_event_enable(u32 event_num) return -ENOENT; } - spin_lock(&sdei_list_lock); - event->reenable = true; - spin_unlock(&sdei_list_lock); + cpus_read_lock(); if (event->type == SDEI_EVENT_TYPE_SHARED) err = sdei_api_event_enable(event->event_num); else err = sdei_do_cross_call(_local_event_enable, event); + + if (!err) { + spin_lock(&sdei_list_lock); + event->reenable = true; + spin_unlock(&sdei_list_lock); + } + cpus_read_unlock(); mutex_unlock(&sdei_events_lock); return err; @@ -619,21 +624,18 @@ int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg) break; } - spin_lock(&sdei_list_lock); - event->reregister = true; - spin_unlock(&sdei_list_lock); - + cpus_read_lock(); err = _sdei_event_register(event); if (err) { - spin_lock(&sdei_list_lock); - event->reregister = false; - event->reenable = false; - spin_unlock(&sdei_list_lock); - sdei_event_destroy(event); pr_warn("Failed to register event %u: %d\n", event_num, err); + } else { + spin_lock(&sdei_list_lock); + event->reregister = true; + spin_unlock(&sdei_list_lock); } + cpus_read_unlock(); } while (0); mutex_unlock(&sdei_events_lock); -- 2.25.1