linux-kernel - [PATCH v4 20/52] PCI: Skip required+optional if there is no optional

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Message-Id: <1440138067-4314-21-git-send-email-yinghai@kernel.org>
Date:	Thu, 20 Aug 2015 23:20:35 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	David Miller <davem@...emloft.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>, TJ <linux@....tj>,
	Yijing Wang <wangyijing@...wei.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH v4 20/52] PCI: Skip required+optional if there is no optional

If the bridge does not support hotplug and no child with sriov support,
We will not have optional resources. We could get out early and
don't try required+optional allocation.

Also in the loop that update res with optional add info, skip resource
that add_size is 0.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 drivers/pci/setup-bus.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 8195929..7d2420d 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -444,6 +444,24 @@ static bool pci_need_to_release(unsigned long mask, struct resource *res)
 	return false;	/* should not get here */
 }
 
+static bool has_addon(struct list_head *head,
+			struct list_head *realloc_head)
+{
+	int add_count = 0;
+	struct pci_dev_resource *dev_res, *tmp_res;
+
+	/* check if we have add really */
+	list_for_each_entry(dev_res, head, list) {
+		tmp_res = res_to_dev_res(realloc_head, dev_res->res);
+		if (!tmp_res || !tmp_res->add_size)
+			continue;
+
+		add_count++;
+	}
+
+	return add_count != 0;
+}
+
 static bool save_resources(struct list_head *head,
 			   struct list_head *save_head)
 {
@@ -475,16 +493,24 @@ static bool __assign_resources_required_optional_sorted(struct list_head *head,
 	struct pci_dev_resource *save_res;
 	struct pci_dev_resource *dev_res, *tmp_res;
 	unsigned long fail_type;
-	resource_size_t add_align;
+	resource_size_t add_align, add_size;
 	struct resource *res;
 
+	if (!has_addon(head, realloc_head))
+		return false;
+
 	if (!save_resources(head, &save_head))
 		return false;
 
 	/* Update res in head list with add_size in realloc_head list */
 	list_for_each_entry(dev_res, head, list) {
 		res = dev_res->res;
-		res->end += get_res_add_size(realloc_head, res);
+		add_size = get_res_add_size(realloc_head, res);
+
+		if (!add_size)
+			continue;
+
+		res->end += add_size;
 
 		/*
 		 * There are two kinds of additional resources in the list:
@@ -572,7 +598,7 @@ static void __assign_resources_sorted(struct list_head *head,
 	 */
 
 	/* Check required+optional add */
-	if (realloc_head && !list_empty(realloc_head) &&
+	if (realloc_head &&
 	    __assign_resources_required_optional_sorted(head, realloc_head))
 		return;
 
-- 
1.8.4.5

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