[PATCH v2] ACPI: scan: Avoid registering platform devices with resource overlaps

From: "Rafael J. Wysocki" <[email protected]>

If acpi_dev_get_resources() returns overlapping I/O or memory resources,
the subsequent registration of a platform device will fail with -EBUSY
due to a resource conflict.  This is reported to happen on Acer Aspire
ES1-572 [1].

Avoid that by adjusting resources returned by acpi_dev_get_resources()
to eliminate partial overlaps between them.

This has not been regarded as necessary before because putting
overlapping resources into the _CRS of one device is really pointless,
but now that the issue has been reported to actually happen in the
field, it needs to be done.

Fixes: ab06eb920401 ("ACPI: scan: Register platform devices for fixed event buttons")
Reported-by: Julien <[email protected]>
Closes: https://lore.kernel.org/linux-integrity/CAJOGg3z6LJPDsdPNBxajgy8_wQxfhYBRxe4EiurZf3kPU5A5Bw@mail.gmail.com/ [1]
Cc: All applicable <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
---

v1 -> v2:
   * Add the expanded resource instead of and not in addition to the other
     overlapping one (Sashiko)

---
 drivers/acpi/acpi_platform.c |   49 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -71,6 +71,47 @@ static struct notifier_block acpi_platfo
 	.notifier_call = acpi_platform_device_remove_notify,
 };
 
+static unsigned int acpi_platform_adjust_resources(struct acpi_device *adev,
+						   struct resource *new_res,
+						   struct resource *resources,
+						   unsigned int count)
+{
+	unsigned int i;
+
+	if (!(new_res->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
+		return count;
+
+	for (i = 0; i < count; ) {
+		struct resource *res = &resources[i];
+
+		if (resource_type(new_res) != resource_type(res) ||
+		    !resource_overlaps(new_res, res)) {
+			i++;
+			continue;
+		}
+
+		dev_info(&adev->dev, "Adjusting %pR for %pR\n", new_res, res);
+		/*
+		 * Extend the new resource to include the one that has been processed
+		 * already.
+		 */
+		if (res->start < new_res->start)
+			new_res->start = res->start;
+
+		if (res->end > new_res->end)
+			new_res->end = res->end;
+
+		/*
+		 * Eliminate the previously processed resource that has
+		 * triggered the adjustment because it is not necessary any
+		 * more.
+		 */
+		memmove(res, res + 1, (--count - i) * sizeof(*res));
+	}
+
+	return count;
+}
+
 static void acpi_platform_fill_resource(struct acpi_device *adev,
 	const struct resource *src, struct resource *dest)
 {
@@ -151,10 +192,14 @@ struct platform_device *acpi_create_plat
 				return ERR_PTR(-ENOMEM);
 			}
 			count = 0;
-			list_for_each_entry(rentry, &resource_list, node)
+			list_for_each_entry(rentry, &resource_list, node) {
+				count = acpi_platform_adjust_resources(adev,
+								       rentry->res,
+								       resources,
+								       count);
 				acpi_platform_fill_resource(adev, rentry->res,
 							    &resources[count++]);
-
+			}
 			acpi_dev_free_resource_list(&resource_list);
 		}
 	}