linux-kernel - [PATCH v2 2/4] PCI: Skip allocate_resource() if too little space available

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Message-Id: <20221208190341.1560157-3-helgaas@kernel.org>
Date:   Thu,  8 Dec 2022 13:03:39 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     linux-pci@...r.kernel.org
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Florent DELAHAYE <kernelorg@...ead.fr>,
        Konrad J Hambrick <kjhambrick@...il.com>,
        Matt Hansen <2lprbe78@...k.com>,
        Benoit Grégoire <benoitg@...us.ca>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Werner Sembach <wse@...edocomputers.com>,
        mumblingdrunkard@...tonmail.com, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v2 2/4] PCI: Skip allocate_resource() if too little space available

From: Bjorn Helgaas <bhelgaas@...gle.com>

pci_bus_alloc_from_region() allocates MMIO space by iterating through all
the resources available on the bus.  The available resource might be
reduced if the caller requires 32-bit space or we're avoiding BIOS or E820
areas.

Don't bother calling allocate_resource() if we need more space than is
available in this resource.  This prevents some pointless and annoying
messages about avoided areas.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Hans de Goede <hdegoede@...hat.com>
---
 drivers/pci/bus.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 3cef835b375f..83ae838ceb5f 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -197,6 +197,10 @@ static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
 
 		max = avail.end;
 
+		/* Don't bother if available space isn't large enough */
+		if (size > max - min_used + 1)
+			continue;
+
 		/* Ok, try it out.. */
 		ret = allocate_resource(r, res, size, min_used, max,
 					align, alignf, alignf_data);
-- 
2.25.1