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=-8.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 AC154C48BD9 for ; Wed, 26 Jun 2019 16:28:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FA34216FD for ; Wed, 26 Jun 2019 16:28:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726523AbfFZQ2e (ORCPT ); Wed, 26 Jun 2019 12:28:34 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:19085 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726014AbfFZQ2d (ORCPT ); Wed, 26 Jun 2019 12:28:33 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 5BE6637B57A44D2D3B5C; Thu, 27 Jun 2019 00:28:31 +0800 (CST) Received: from localhost.localdomain (10.67.212.75) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.439.0; Thu, 27 Jun 2019 00:28:25 +0800 From: John Garry To: CC: , , , , , John Garry Subject: [PATCH v3 1/6] lib: logic_pio: Fix RCU usage Date: Thu, 27 Jun 2019 00:26:53 +0800 Message-ID: <1561566418-22714-2-git-send-email-john.garry@huawei.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1561566418-22714-1-git-send-email-john.garry@huawei.com> References: <1561566418-22714-1-git-send-email-john.garry@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.67.212.75] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The traversing of io_range_list with list_for_each_entry_rcu() is not properly protected by rcu_read_lock() and rcu_read_unlock(), so add them. These functions mark the critical section scope where the list is protected for the reader, it cannot be "reclaimed". Any updater - in this case, the logical PIO registration functions - cannot update the list until the reader exits this critical section. In addition, the list traversing used in logic_pio_register_range() does not need to use the rcu variant. This is because we are already using io_range_mutex to guarantee mutual exclusion from mutating the list. Fixes: 031e3601869c ("lib: Add generic PIO mapping method") Signed-off-by: John Garry --- lib/logic_pio.c | 49 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 35 insertions(+), 14 deletions(-) diff --git a/lib/logic_pio.c b/lib/logic_pio.c index feea48fd1a0d..761296376fbc 100644 --- a/lib/logic_pio.c +++ b/lib/logic_pio.c @@ -46,7 +46,7 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) end = new_range->hw_start + new_range->size; mutex_lock(&io_range_mutex); - list_for_each_entry_rcu(range, &io_range_list, list) { + list_for_each_entry(range, &io_range_list, list) { if (range->fwnode == new_range->fwnode) { /* range already there */ goto end_register; @@ -108,26 +108,38 @@ int logic_pio_register_range(struct logic_pio_hwaddr *new_range) */ struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode) { - struct logic_pio_hwaddr *range; + struct logic_pio_hwaddr *range, *found_range = NULL; + rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { - if (range->fwnode == fwnode) - return range; + if (range->fwnode == fwnode) { + found_range = range; + break; + } } - return NULL; + rcu_read_unlock(); + + return found_range; } /* Return a registered range given an input PIO token */ static struct logic_pio_hwaddr *find_io_range(unsigned long pio) { - struct logic_pio_hwaddr *range; + struct logic_pio_hwaddr *range, *found_range = NULL; + rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { - if (in_range(pio, range->io_start, range->size)) - return range; + if (in_range(pio, range->io_start, range->size)) { + found_range = range; + break; + } } - pr_err("PIO entry token %lx invalid\n", pio); - return NULL; + rcu_read_unlock(); + + if (!found_range) + pr_err("PIO entry token 0x%lx invalid\n", pio); + + return found_range; } /** @@ -180,14 +192,23 @@ unsigned long logic_pio_trans_cpuaddr(resource_size_t addr) { struct logic_pio_hwaddr *range; + rcu_read_lock(); list_for_each_entry_rcu(range, &io_range_list, list) { if (range->flags != LOGIC_PIO_CPU_MMIO) continue; - if (in_range(addr, range->hw_start, range->size)) - return addr - range->hw_start + range->io_start; + if (in_range(addr, range->hw_start, range->size)) { + unsigned long cpuaddr; + + cpuaddr = addr - range->hw_start + range->io_start; + + rcu_read_unlock(); + return cpuaddr; + } } - pr_err("addr %llx not registered in io_range_list\n", - (unsigned long long) addr); + rcu_read_unlock(); + + pr_err("addr %pa not registered in io_range_list\n", &addr); + return ~0UL; } -- 2.17.1