linux-kernel - [PATCH v12 3/4] PCI: Change extend_bridge_window() to set resource size directly

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Date:   Mon, 9 Dec 2019 13:00:31 +0000
From:   Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Logan Gunthorpe <logang@...tatee.com>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
Subject: [PATCH v12 3/4] PCI: Change extend_bridge_window() to set resource
 size directly

Change extend_bridge_window() to set resource size directly instead of
using additional resource lists.

Because additional resource lists are optional resources, any algorithm
that requires guaranteed allocation that uses them cannot be guaranteed
to work.

Remove the resource from add_list, as a zero-sized additional resource
is redundant.

Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/pci/setup-bus.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 165a62a79..0e0c8b677 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1836,7 +1836,7 @@ static void extend_bridge_window(struct pci_dev *bridge, struct resource *res,
 				 struct list_head *add_list,
 				 resource_size_t new_size)
 {
-	struct pci_dev_resource *dev_res;
+	resource_size_t add_size;
 
 	if (res->parent)
 		return;
@@ -1844,17 +1844,10 @@ static void extend_bridge_window(struct pci_dev *bridge, struct resource *res,
 	if (resource_size(res) >= new_size)
 		return;
 
-	dev_res = res_to_dev_res(add_list, res);
-	if (!dev_res)
-		return;
-
-	/* Is there room to extend the window? */
-	if (new_size - resource_size(res) <= dev_res->add_size)
-		return;
-
-	dev_res->add_size = new_size - resource_size(res);
-	pci_dbg(bridge, "bridge window %pR extended by %pa\n", res,
-		&dev_res->add_size);
+	add_size = new_size - resource_size(res);
+	pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, &add_size);
+	res->end = res->start + new_size - 1;
+	remove_from_list(add_list, res);
 }
 
 static void pci_bus_distribute_available_resources(struct pci_bus *bus,
-- 
2.24.0