linux-kernel - [PATCH v7 2/8] PCI: Skip resource distribution when no hotplug bridges

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Date:   Mon, 1 Jul 2019 14:23:32 +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>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "corbet@....net" <corbet@....net>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "logang@...tatee.com" <logang@...tatee.com>
Subject: [PATCH v7 2/8] PCI: Skip resource distribution when no hotplug
 bridges

If "hotplug_bridges == 0", "!dev->is_hotplug_bridge" is always true, so the
loop that divides the remaining resources among hotplug-capable bridges
does nothing.

Check for "hotplug_bridges == 0" earlier, so we don't even have to compute
the amount of remaining resources.  No functional change intended.

Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
---
 drivers/pci/setup-bus.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index af28af898..04adeebe8 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1887,6 +1887,9 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
 		return;
 	}
 
+	if (hotplug_bridges == 0)
+		return;
+
 	/*
 	 * Calculate the total amount of extra resource space we can
 	 * pass to bridges below this one.  This is basically the
@@ -1936,8 +1939,6 @@ static void pci_bus_distribute_available_resources(struct pci_bus *bus,
 		 * Distribute available extra resources equally between
 		 * hotplug-capable downstream ports taking alignment into
 		 * account.
-		 *
-		 * Here hotplug_bridges is always != 0.
 		 */
 		align = pci_resource_alignment(bridge, io_res);
 		io = div64_ul(available_io, hotplug_bridges);
-- 
2.20.1