[PATCH v3] ACPI: scan: Avoid registering platform devices with resource overlaps

["Rafael J. Wysocki" <rafael@kernel.org>]

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

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 <julien82453@gmail.com>
Closes: https://lore.kernel.org/linux-integrity/CAJOGg3z6LJPDsdPNBxajgy8_wQxfhYBRxe4EiurZf3kPU5A5Bw@mail.gmail.com/ [1]
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v2 -> v3:
   * Use resource_union() and adjust code and comment (Andy)
   * Include ioport.h directly

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

---
 drivers/acpi/acpi_platform.c |   39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -12,6 +12,7 @@
 #include <linux/bits.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/dma-mapping.h>
@@ -71,6 +72,36 @@ 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_union(new_res, res, new_res)) {
+			i++;
+			continue;
+		}
+
+		dev_info(&adev->dev, "%pR expanded to avoid overlap\n", new_res);
+		/*
+		 * Eliminate the previously processed resource that overlapped
+		 * with the new one 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 +182,14 @@ 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);
 		}
 	}