ACPI / PNP: Avoid conflicting resource reservations

Commit b9a5e5e "ACPI / init: Fix the ordering of
acpi_reserve_resources()" overlooked the fact that the memory
and/or I/O regions reserved by acpi_reserve_resources() may
conflict with those reserved by the PNP "system" driver.

If that conflict actually takes place, it causes the reservations
made by the "system" driver to fail while before commit b9a5e5e
all reservations made by it and by acpi_reserve_resources() would be
successful.  In turn, that allows the resources that haven't been
reserved by the "system" driver to be used by others (e.g. PCI) which
sometimes leads to functional problems (up to and including boot
failures).

To fix that issue, introduce a common resource reservation routine,
acpi_reserve_region(), to be used by both acpi_reserve_resources()
and the "system" driver, that will track all resources reserved by
it and avoid making conflicting requests.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=99831
Link: http://marc.info/?t=143389402600001&r=1&w=2
Fixes: b9a5e5e "ACPI / init: Fix the ordering of acpi_reserve_resources()"
Reported-by: Roland Dreier <roland@purestorage.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/osl.c

@@ -175,11 +175,7 @@ static void __init acpi_request_region (struct acpi_generic_address *gas,
 	if (!addr || !length)
 		return;
 
-	/* Resources are never freed */
-	if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_IO)
-		request_region(addr, length, desc);
-	else if (gas->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
-		request_mem_region(addr, length, desc);
+	acpi_reserve_region(addr, length, gas->space_id, 0, desc);
 }
 
 static void __init acpi_reserve_resources(void)

drivers/acpi/resource.c

@@ -26,6 +26,7 @@
 #include <linux/device.h>
 #include <linux/export.h>
 #include <linux/ioport.h>
+#include <linux/list.h>
 #include <linux/slab.h>
 
 #ifdef CONFIG_X86
@@ -621,3 +622,162 @@ int acpi_dev_filter_resource_type(struct acpi_resource *ares,
 	return (type & types) ? 0 : 1;
 }
 EXPORT_SYMBOL_GPL(acpi_dev_filter_resource_type);
+
+struct reserved_region {
+	struct list_head node;
+	u64 start;
+	u64 end;
+};
+
+static LIST_HEAD(reserved_io_regions);
+static LIST_HEAD(reserved_mem_regions);
+
+static int request_range(u64 start, u64 end, u8 space_id, unsigned long flags,
+			 char *desc)
+{
+	unsigned int length = end - start + 1;
+	struct resource *res;
+
+	res = space_id == ACPI_ADR_SPACE_SYSTEM_IO ?
+		request_region(start, length, desc) :
+		request_mem_region(start, length, desc);
+	if (!res)
+		return -EIO;
+
+	res->flags &= ~flags;
+	return 0;
+}
+
+static int add_region_before(u64 start, u64 end, u8 space_id,
+			     unsigned long flags, char *desc,
+			     struct list_head *head)
+{
+	struct reserved_region *reg;
+	int error;
+
+	reg = kmalloc(sizeof(*reg), GFP_KERNEL);
+	if (!reg)
+		return -ENOMEM;
+
+	error = request_range(start, end, space_id, flags, desc);
+	if (error)
+		return error;
+
+	reg->start = start;
+	reg->end = end;
+	list_add_tail(&reg->node, head);
+	return 0;
+}
+
+/**
+ * acpi_reserve_region - Reserve an I/O or memory region as a system resource.
+ * @start: Starting address of the region.
+ * @length: Length of the region.
+ * @space_id: Identifier of address space to reserve the region from.
+ * @flags: Resource flags to clear for the region after requesting it.
+ * @desc: Region description (for messages).
+ *
+ * Reserve an I/O or memory region as a system resource to prevent others from
+ * using it.  If the new region overlaps with one of the regions (in the given
+ * address space) already reserved by this routine, only the non-overlapping
+ * parts of it will be reserved.
+ *
+ * Returned is either 0 (success) or a negative error code indicating a resource
+ * reservation problem.  It is the code of the first encountered error, but the
+ * routine doesn't abort until it has attempted to request all of the parts of
+ * the new region that don't overlap with other regions reserved previously.
+ *
+ * The resources requested by this routine are never released.
+ */
+int acpi_reserve_region(u64 start, unsigned int length, u8 space_id,
+			unsigned long flags, char *desc)
+{
+	struct list_head *regions;
+	struct reserved_region *reg;
+	u64 end = start + length - 1;
+	int ret = 0, error = 0;
+
+	if (space_id == ACPI_ADR_SPACE_SYSTEM_IO)
+		regions = &reserved_io_regions;
+	else if (space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		regions = &reserved_mem_regions;
+	else
+		return -EINVAL;
+
+	if (list_empty(regions))
+		return add_region_before(start, end, space_id, flags, desc, regions);
+
+	list_for_each_entry(reg, regions, node)
+		if (reg->start == end + 1) {
+			/* The new region can be prepended to this one. */
+			ret = request_range(start, end, space_id, flags, desc);
+			if (!ret)
+				reg->start = start;
+
+			return ret;
+		} else if (reg->start > end) {
+			/* No overlap.  Add the new region here and get out. */
+			return add_region_before(start, end, space_id, flags,
+						 desc, &reg->node);
+		} else if (reg->end == start - 1) {
+			goto combine;
+		} else if (reg->end >= start) {
+			goto overlap;
+		}
+
+	/* The new region goes after the last existing one. */
+	return add_region_before(start, end, space_id, flags, desc, regions);
+
+ overlap:
+	/*
+	 * The new region overlaps an existing one.
+	 *
+	 * The head part of the new region immediately preceding the existing
+	 * overlapping one can be combined with it right away.
+	 */
+	if (reg->start > start) {
+		error = request_range(start, reg->start - 1, space_id, flags, desc);
+		if (error)
+			ret = error;
+		else
+			reg->start = start;
+	}
+
+ combine:
+	/*
+	 * The new region is adjacent to an existing one.  If it extends beyond
+	 * that region all the way to the next one, it is possible to combine
+	 * all three of them.
+	 */
+	while (reg->end < end) {
+		struct reserved_region *next = NULL;
+		u64 a = reg->end + 1, b = end;
+
+		if (!list_is_last(&reg->node, regions)) {
+			next = list_next_entry(reg, node);
+			if (next->start <= end)
+				b = next->start - 1;
+		}
+		error = request_range(a, b, space_id, flags, desc);
+		if (!error) {
+			if (next && next->start == b + 1) {
+				reg->end = next->end;
+				list_del(&next->node);
+				kfree(next);
+			} else {
+				reg->end = end;
+				break;
+			}
+		} else if (next) {
+			if (!ret)
+				ret = error;
+
+			reg = next;
+		} else {
+			break;
+		}
+	}
+
+	return ret ? ret : error;
+}
+EXPORT_SYMBOL_GPL(acpi_reserve_region);

drivers/pnp/system.c

@@ -7,6 +7,7 @@
  *	Bjorn Helgaas <bjorn.helgaas@hp.com>
  */
 
+#include <linux/acpi.h>
 #include <linux/pnp.h>
 #include <linux/device.h>
 #include <linux/init.h>
@@ -22,25 +23,41 @@ static const struct pnp_device_id pnp_dev_table[] = {
 	{"", 0}
 };
 
+#ifdef CONFIG_ACPI
+static bool __reserve_range(u64 start, unsigned int length, bool io, char *desc)
+{
+	u8 space_id = io ? ACPI_ADR_SPACE_SYSTEM_IO : ACPI_ADR_SPACE_SYSTEM_MEMORY;
+	return !acpi_reserve_region(start, length, space_id, IORESOURCE_BUSY, desc);
+}
+#else
+static bool __reserve_range(u64 start, unsigned int length, bool io, char *desc)
+{
+	struct resource *res;
+
+	res = io ? request_region(start, length, desc) :
+		request_mem_region(start, length, desc);
+	if (res) {
+		res->flags &= ~IORESOURCE_BUSY;
+		return true;
+	}
+	return false;
+}
+#endif
+
 static void reserve_range(struct pnp_dev *dev, struct resource *r, int port)
 {
 	char *regionid;
 	const char *pnpid = dev_name(&dev->dev);
 	resource_size_t start = r->start, end = r->end;
-	struct resource *res;
+	bool reserved;
 
 	regionid = kmalloc(16, GFP_KERNEL);
 	if (!regionid)
 		return;
 
 	snprintf(regionid, 16, "pnp %s", pnpid);
-	if (port)
-		res = request_region(start, end - start + 1, regionid);
-	else
-		res = request_mem_region(start, end - start + 1, regionid);
-	if (res)
-		res->flags &= ~IORESOURCE_BUSY;
-	else
+	reserved = __reserve_range(start, end - start + 1, !!port, regionid);
+	if (!reserved)
 		kfree(regionid);
 
 	/*
@@ -49,7 +66,7 @@ static void reserve_range(struct pnp_dev *dev, struct resource *r, int port)
 	 * have double reservations.
 	 */
 	dev_info(&dev->dev, "%pR %s reserved\n", r,
-		 res ? "has been" : "could not be");
+		 reserved ? "has been" : "could not be");
 }
 
 static void reserve_resources_of_dev(struct pnp_dev *dev)

include/linux/acpi.h

@@ -332,6 +332,9 @@ int acpi_check_region(resource_size_t start, resource_size_t n,
 
 int acpi_resources_are_enforced(void);
 
+int acpi_reserve_region(u64 start, unsigned int length, u8 space_id,
+			unsigned long flags, char *desc);
+
 #ifdef CONFIG_HIBERNATION
 void __init acpi_no_s4_hw_signature(void);
 #endif
@@ -525,6 +528,13 @@ static inline int acpi_check_region(resource_size_t start, resource_size_t n,
 	return 0;
 }
 
+static inline int acpi_reserve_region(u64 start, unsigned int length,
+				      u8 space_id, unsigned long flags,
+				      char *desc)
+{
+	return -ENXIO;
+}
+
 struct acpi_table_header;
 static inline int acpi_table_parse(char *id,
 				int (*handler)(struct acpi_table_header *))