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=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNWANTED_LANGUAGE_BODY,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 852CCC388F9 for ; Tue, 3 Nov 2020 21:12:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3778722226 for ; Tue, 3 Nov 2020 21:12:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437936; bh=dV0oHAJrbtnLgh/JMhACTm5bLtrHPT2g2ubmqUEGnZI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OyOdZOefhXun5GzjsfkVkhtcQ2cIpBv34RrmzU7yXoUde5ymgMGckyRFkOObP/LUF tnVBrKFrstBLo97zK2pyn4KDp3JJPEkmyN3Qyqisl+VMDgGsmNwETcBO1cr8P7XnU/ i8K+fuXKy5D2Sri0b1Iu5dk89Yph6mB4C5JVd/ZI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388016AbgKCVMP (ORCPT ); Tue, 3 Nov 2020 16:12:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:54366 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388973AbgKCVMK (ORCPT ); Tue, 3 Nov 2020 16:12:10 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F2A82206B5; Tue, 3 Nov 2020 21:12:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437929; bh=dV0oHAJrbtnLgh/JMhACTm5bLtrHPT2g2ubmqUEGnZI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rUnYjno0bWcfhmUHuvIQfutOW3AdmGQaMrWUkx7KCcByPMy4iEw8mvS/QjSO40gP8 eb1DdXaQtG9YcANd2T9XGRH0W5Ag+781H25yHl2jJmdoIibi1r6v5+eevIJ8Ul6/Nj 62mXhT/g8J7FE6MWOqF/akLOG3/zKYuZMlsFh0fU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Schnelle , Alexander Egorenkov , Vasily Gorbik Subject: [PATCH 4.14 091/125] s390/stp: add locking to sysfs functions Date: Tue, 3 Nov 2020 21:37:48 +0100 Message-Id: <20201103203210.033449871@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203156.372184213@linuxfoundation.org> References: <20201103203156.372184213@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: Sven Schnelle commit b3bd02495cb339124f13135d51940cf48d83e5cb upstream. The sysfs function might race with stp_work_fn. To prevent that, add the required locking. Another issue is that the sysfs functions are checking the stp_online flag, but this flag just holds the user setting whether STP is enabled. Add a flag to clock_sync_flag whether stp_info holds valid data and use that instead. Cc: stable@vger.kernel.org Signed-off-by: Sven Schnelle Reviewed-by: Alexander Egorenkov Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/time.c | 118 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 85 insertions(+), 33 deletions(-) --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -347,8 +347,9 @@ static DEFINE_PER_CPU(atomic_t, clock_sy static DEFINE_MUTEX(clock_sync_mutex); static unsigned long clock_sync_flags; -#define CLOCK_SYNC_HAS_STP 0 -#define CLOCK_SYNC_STP 1 +#define CLOCK_SYNC_HAS_STP 0 +#define CLOCK_SYNC_STP 1 +#define CLOCK_SYNC_STPINFO_VALID 2 /* * The get_clock function for the physical clock. It will get the current @@ -585,6 +586,22 @@ void stp_queue_work(void) queue_work(time_sync_wq, &stp_work); } +static int __store_stpinfo(void) +{ + int rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi)); + + if (rc) + clear_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags); + else + set_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags); + return rc; +} + +static int stpinfo_valid(void) +{ + return stp_online && test_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags); +} + static int stp_sync_clock(void *data) { struct clock_sync_data *sync = data; @@ -606,8 +623,7 @@ static int stp_sync_clock(void *data) if (rc == 0) { sync->clock_delta = clock_delta; clock_sync_global(clock_delta); - rc = chsc_sstpi(stp_page, &stp_info, - sizeof(struct stp_sstpi)); + rc = __store_stpinfo(); if (rc == 0 && stp_info.tmd != 2) rc = -EAGAIN; } @@ -652,7 +668,7 @@ static void stp_work_fn(struct work_stru if (rc) goto out_unlock; - rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi)); + rc = __store_stpinfo(); if (rc || stp_info.c == 0) goto out_unlock; @@ -689,10 +705,14 @@ static ssize_t stp_ctn_id_show(struct de struct device_attribute *attr, char *buf) { - if (!stp_online) - return -ENODATA; - return sprintf(buf, "%016llx\n", - *(unsigned long long *) stp_info.ctnid); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid()) + ret = sprintf(buf, "%016llx\n", + *(unsigned long long *) stp_info.ctnid); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(ctn_id, 0400, stp_ctn_id_show, NULL); @@ -701,9 +721,13 @@ static ssize_t stp_ctn_type_show(struct struct device_attribute *attr, char *buf) { - if (!stp_online) - return -ENODATA; - return sprintf(buf, "%i\n", stp_info.ctn); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid()) + ret = sprintf(buf, "%i\n", stp_info.ctn); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(ctn_type, 0400, stp_ctn_type_show, NULL); @@ -712,9 +736,13 @@ static ssize_t stp_dst_offset_show(struc struct device_attribute *attr, char *buf) { - if (!stp_online || !(stp_info.vbits & 0x2000)) - return -ENODATA; - return sprintf(buf, "%i\n", (int)(s16) stp_info.dsto); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid() && (stp_info.vbits & 0x2000)) + ret = sprintf(buf, "%i\n", (int)(s16) stp_info.dsto); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(dst_offset, 0400, stp_dst_offset_show, NULL); @@ -723,9 +751,13 @@ static ssize_t stp_leap_seconds_show(str struct device_attribute *attr, char *buf) { - if (!stp_online || !(stp_info.vbits & 0x8000)) - return -ENODATA; - return sprintf(buf, "%i\n", (int)(s16) stp_info.leaps); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid() && (stp_info.vbits & 0x8000)) + ret = sprintf(buf, "%i\n", (int)(s16) stp_info.leaps); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(leap_seconds, 0400, stp_leap_seconds_show, NULL); @@ -734,9 +766,13 @@ static ssize_t stp_stratum_show(struct d struct device_attribute *attr, char *buf) { - if (!stp_online) - return -ENODATA; - return sprintf(buf, "%i\n", (int)(s16) stp_info.stratum); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid()) + ret = sprintf(buf, "%i\n", (int)(s16) stp_info.stratum); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(stratum, 0400, stp_stratum_show, NULL); @@ -745,9 +781,13 @@ static ssize_t stp_time_offset_show(stru struct device_attribute *attr, char *buf) { - if (!stp_online || !(stp_info.vbits & 0x0800)) - return -ENODATA; - return sprintf(buf, "%i\n", (int) stp_info.tto); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid() && (stp_info.vbits & 0x0800)) + ret = sprintf(buf, "%i\n", (int) stp_info.tto); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(time_offset, 0400, stp_time_offset_show, NULL); @@ -756,9 +796,13 @@ static ssize_t stp_time_zone_offset_show struct device_attribute *attr, char *buf) { - if (!stp_online || !(stp_info.vbits & 0x4000)) - return -ENODATA; - return sprintf(buf, "%i\n", (int)(s16) stp_info.tzo); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid() && (stp_info.vbits & 0x4000)) + ret = sprintf(buf, "%i\n", (int)(s16) stp_info.tzo); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(time_zone_offset, 0400, @@ -768,9 +812,13 @@ static ssize_t stp_timing_mode_show(stru struct device_attribute *attr, char *buf) { - if (!stp_online) - return -ENODATA; - return sprintf(buf, "%i\n", stp_info.tmd); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid()) + ret = sprintf(buf, "%i\n", stp_info.tmd); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(timing_mode, 0400, stp_timing_mode_show, NULL); @@ -779,9 +827,13 @@ static ssize_t stp_timing_state_show(str struct device_attribute *attr, char *buf) { - if (!stp_online) - return -ENODATA; - return sprintf(buf, "%i\n", stp_info.tst); + ssize_t ret = -ENODATA; + + mutex_lock(&stp_work_mutex); + if (stpinfo_valid()) + ret = sprintf(buf, "%i\n", stp_info.tst); + mutex_unlock(&stp_work_mutex); + return ret; } static DEVICE_ATTR(timing_state, 0400, stp_timing_state_show, NULL);