From patchwork Thu Jul 1 09:56:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 1499488 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=P+LXl628; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4GFts827f4z9sWk for ; Thu, 1 Jul 2021 19:56:28 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235344AbhGAJ64 (ORCPT ); Thu, 1 Jul 2021 05:58:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235407AbhGAJ64 (ORCPT ); Thu, 1 Jul 2021 05:58:56 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09BD1C061756; Thu, 1 Jul 2021 02:56:26 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id s13so244913plg.12; Thu, 01 Jul 2021 02:56:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=fGp58ukWUgFNLNhUEszoUgod+B2Y1jdAd3W7aV7VkJY=; b=P+LXl628SjFB1WBcCwQqlE8yK8NlzFZQiqyTYD+MCvEoLbY3EaT2185B0CHnG0mQFu ICeefTCt4X3H8na7ouxyOEpaPmGTSBM3pUSJYnoa63He45FQQ9tAEtwIGdHrWL+fAIrr +xuLhCKFSZf5Y/pI7TQNA6cBWbecqJtHFuEZ4b7FiBo55/q4FIa35L/emGvN2fpxj/NN atZQ+FxqAORG6KpEXORWH5PAwNLfU2Sct7oi23868vKyi/C6AYMMw1jdfGRqflys9o/k hyClQWdlKAsTiFWQuMxT0XCbBaDmBdEenbwq4ATrAcTmJFijcvbGUc81ZM3OWTUq9Ox9 bHgw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=fGp58ukWUgFNLNhUEszoUgod+B2Y1jdAd3W7aV7VkJY=; b=OpmR2zOggRLEjahs98/KidW3mDjpClN3BTF2uFgax5nm3Y89lOrr/1nZeTiUD1cOli Xqk14B+5iqFn53WJjQbaWeNwqPs/hwVez8VruRrDQ1GcYhUYyA390/kH/oHGFu8kemEX y3UrgSd83jOfRRQenx6+Gn6bNW7sdJLPbJLUxXgfMz0G2T54LzG30pRonjFHAA/MHbUh blDWuy1GAezUyB2L0Jkty2DAH3qZdZ9cKsVQJDagW/RsxOA2BbG0ND8YnT2158krbD1v 6MNEi6h2e850FY/hlGNHpF89Ef5duXrjbXJT7YH5n2ZtGwd7ypJCU6cDBHXUV14+0nuA rleA== X-Gm-Message-State: AOAM532rHy1zhwCTQ0Aqpc7DVwcKLY2EIIFnU523/9gVncCWSNIl7Zjt bQl1pHxZx7SUihHHngNiskU= X-Google-Smtp-Source: ABdhPJyK0CF8WcXv4dauRF8S/8oRWmloHOS5zUBljTdoBpJsYxZlCkjJ9/XnVHZVvBdfghHZhRM3Bw== X-Received: by 2002:a17:90a:1b0b:: with SMTP id q11mr19098332pjq.148.1625133385610; Thu, 01 Jul 2021 02:56:25 -0700 (PDT) Received: from edumazet1.svl.corp.google.com ([2620:15c:2c4:201:76c6:e9cb:e399:2879]) by smtp.gmail.com with ESMTPSA id cl14sm1842213pjb.40.2021.07.01.02.56.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Jul 2021 02:56:25 -0700 (PDT) From: Eric Dumazet To: Bjorn Helgaas Cc: linux-kernel , Eric Dumazet , Eric Dumazet , Dan Williams , Ira Weiny , Logan Gunthorpe , Christoph Hellwig , Greg Kroah-Hartman , =?utf-8?b?SsOpcsO0bWUgR2xp?= =?utf-8?b?c3Nl?= , "Rafael J. Wysocki" , linux-pci@vger.kernel.org Subject: [PATCH] PCI/P2PDMA: finish RCU conversion of pdev->p2pdma Date: Thu, 1 Jul 2021 02:56:21 -0700 Message-Id: <20210701095621.3129283-1-eric.dumazet@gmail.com> X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Eric Dumazet While looking at pci_alloc_p2pmem() I found rcu protection was not properly applied there, as pdev->p2pdma was potentially read multiple times. I decided to fix pci_alloc_p2pmem(), add __rcu qualifier to p2pdma field of struct pci_dev, and fix all other accesses to this field with proper rcu verbs. Fixes: 1570175abd16 ("PCI/P2PDMA: track pgmap references per resource, not globally") Signed-off-by: Eric Dumazet Cc: Dan Williams Cc: Ira Weiny Cc: Logan Gunthorpe Cc: Bjorn Helgaas Cc: Christoph Hellwig Cc: Greg Kroah-Hartman Cc: "Jérôme Glisse" Cc: "Rafael J. Wysocki" Cc: linux-pci@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: Logan Gunthorpe --- drivers/pci/p2pdma.c | 101 ++++++++++++++++++++++++++++++------------- include/linux/pci.h | 2 +- 2 files changed, 73 insertions(+), 30 deletions(-) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 1963826303631465da2956b0e3abcec3e0fcfbc4..89095aa5c674f5b8237d543c7af2bbdc2c176e5a 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -48,10 +48,14 @@ static ssize_t size_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; size_t size = 0; - if (pdev->p2pdma->pool) - size = gen_pool_size(pdev->p2pdma->pool); + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma && p2pdma->pool) + size = gen_pool_size(p2pdma->pool); + rcu_read_unlock(); return scnprintf(buf, PAGE_SIZE, "%zd\n", size); } @@ -61,10 +65,14 @@ static ssize_t available_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; size_t avail = 0; - if (pdev->p2pdma->pool) - avail = gen_pool_avail(pdev->p2pdma->pool); + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma && p2pdma->pool) + avail = gen_pool_avail(p2pdma->pool); + rcu_read_unlock(); return scnprintf(buf, PAGE_SIZE, "%zd\n", avail); } @@ -74,9 +82,16 @@ static ssize_t published_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; + bool published = false; + + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma) + published = p2pdma->p2pmem_published; + rcu_read_unlock(); - return scnprintf(buf, PAGE_SIZE, "%d\n", - pdev->p2pdma->p2pmem_published); + return scnprintf(buf, PAGE_SIZE, "%d\n", published); } static DEVICE_ATTR_RO(published); @@ -95,8 +110,9 @@ static const struct attribute_group p2pmem_group = { static void pci_p2pdma_release(void *data) { struct pci_dev *pdev = data; - struct pci_p2pdma *p2pdma = pdev->p2pdma; + struct pci_p2pdma *p2pdma; + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); if (!p2pdma) return; @@ -128,16 +144,14 @@ static int pci_p2pdma_setup(struct pci_dev *pdev) if (error) goto out_pool_destroy; - pdev->p2pdma = p2p; - error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); if (error) goto out_pool_destroy; + rcu_assign_pointer(pdev->p2pdma, p2p); return 0; out_pool_destroy: - pdev->p2pdma = NULL; gen_pool_destroy(p2p->pool); out: devm_kfree(&pdev->dev, p2p); @@ -159,6 +173,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, { struct pci_p2pdma_pagemap *p2p_pgmap; struct dev_pagemap *pgmap; + struct pci_p2pdma *p2pdma; void *addr; int error; @@ -200,7 +215,8 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, goto pgmap_free; } - error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr, + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); + error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr, pci_bus_address(pdev, bar) + offset, range_len(&pgmap->range), dev_to_node(&pdev->dev), pgmap->ref); @@ -476,6 +492,7 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, int *dist, bool *acs_redirects, struct seq_buf *acs_list) { enum pci_p2pdma_map_type map_type; + struct pci_p2pdma *p2pdma; map_type = __upstream_bridge_distance(provider, client, dist, acs_redirects, acs_list); @@ -486,10 +503,12 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; } - if (provider->p2pdma) - xa_store(&provider->p2pdma->map_types, map_types_idx(client), - xa_mk_value(map_type), GFP_KERNEL); - + rcu_read_lock(); + p2pdma = rcu_dereference(provider->p2pdma); + if (p2pdma) + xa_store(&p2pdma->map_types, map_types_idx(client), + xa_mk_value(map_type), GFP_ATOMIC); + rcu_read_unlock(); return map_type; } @@ -595,7 +614,15 @@ EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many); */ bool pci_has_p2pmem(struct pci_dev *pdev) { - return pdev->p2pdma && pdev->p2pdma->p2pmem_published; + struct pci_p2pdma *p2pdma; + bool res; + + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + res = p2pdma && p2pdma->p2pmem_published; + rcu_read_unlock(); + + return res; } EXPORT_SYMBOL_GPL(pci_has_p2pmem); @@ -675,6 +702,7 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) { void *ret = NULL; struct percpu_ref *ref; + struct pci_p2pdma *p2pdma; /* * Pairs with synchronize_rcu() in pci_p2pdma_release() to @@ -682,16 +710,17 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) * read-lock. */ rcu_read_lock(); - if (unlikely(!pdev->p2pdma)) + p2pdma = rcu_dereference(pdev->p2pdma); + if (unlikely(!p2pdma)) goto out; - ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size, + ret = (void *)gen_pool_alloc_owner(p2pdma->pool, size, (void **) &ref); if (!ret) goto out; if (unlikely(!percpu_ref_tryget_live(ref))) { - gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size); + gen_pool_free(p2pdma->pool, (unsigned long) ret, size); ret = NULL; goto out; } @@ -710,9 +739,9 @@ EXPORT_SYMBOL_GPL(pci_alloc_p2pmem); void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size) { struct percpu_ref *ref; + struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); - gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size, - (void **) &ref); + gen_pool_free_owner(p2pdma->pool, (uintptr_t)addr, size, (void **) &ref); percpu_ref_put(ref); } EXPORT_SYMBOL_GPL(pci_free_p2pmem); @@ -725,9 +754,12 @@ EXPORT_SYMBOL_GPL(pci_free_p2pmem); */ pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) { + struct pci_p2pdma *p2pdma; + if (!addr) return 0; - if (!pdev->p2pdma) + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); + if (!p2pdma) return 0; /* @@ -735,7 +767,7 @@ pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) * bus address as the physical address. So gen_pool_virt_to_phys() * actually returns the bus address despite the misleading name. */ - return gen_pool_virt_to_phys(pdev->p2pdma->pool, (unsigned long)addr); + return gen_pool_virt_to_phys(p2pdma->pool, (unsigned long)addr); } EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus); @@ -806,19 +838,30 @@ EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl); */ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) { - if (pdev->p2pdma) - pdev->p2pdma->p2pmem_published = publish; + struct pci_p2pdma *p2pdma; + + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma) + p2pdma->p2pmem_published = publish; + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(pci_p2pmem_publish); static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct pci_dev *provider, struct pci_dev *client) { - if (!provider->p2pdma) - return PCI_P2PDMA_MAP_NOT_SUPPORTED; + enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED; + struct pci_p2pdma *p2pdma; - return xa_to_value(xa_load(&provider->p2pdma->map_types, - map_types_idx(client))); + rcu_read_lock(); + p2pdma = rcu_dereference(provider->p2pdma); + + if (p2pdma) + type = xa_to_value(xa_load(&p2pdma->map_types, + map_types_idx(client))); + rcu_read_unlock(); + return type; } static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap, diff --git a/include/linux/pci.h b/include/linux/pci.h index 24306504226ab665be7323549d0759da1b7ac715..6abdebe2aeb1676da08f03e05e5ecb26f0b08cd6 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -497,7 +497,7 @@ struct pci_dev { u16 pasid_features; #endif #ifdef CONFIG_PCI_P2PDMA - struct pci_p2pdma *p2pdma; + struct pci_p2pdma __rcu *p2pdma; #endif u16 acs_cap; /* ACS Capability offset */ phys_addr_t rom; /* Physical address if not from BAR */