Merge tag 'acpi-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI updates from Rafael Wysocki:
 "These eliminate significant AML processing overhead related to using
  operation regions in system memory, update the ACPICA code in the
  kernel to upstream revision 20200717 (including a fix to prevent
  operation region reference counts from overflowing in some cases),
  remove the last bits of the (long deprecated) ACPI procfs interface
  and do some assorted cleanups.

  Specifics:

   - Eliminate significant AML processing overhead related to using
     operation regions in system memory by reworking the management of
     memory mappings in the ACPI code to defer unmap operations (to do
     them outside of the ACPICA locks, among other things) and making
     the memory operation reagion handler avoid releasing memory
     mappings created by it too early (Rafael Wysocki).

   - Update the ACPICA code in the kernel to upstream revision 20200717:

       * Prevent operation region reference counts from overflowing in
         some cases (Erik Kaneda).

       * Replace one-element array with flexible-array (Gustavo A. R.
         Silva).

   - Fix ACPI PCI hotplug reference counting (Rafael Wysocki).

   - Drop last bits of the ACPI procfs interface (Thomas Renninger).

   - Drop some redundant checks from the code parsing ACPI tables
     related to NUMA (Hanjun Guo).

   - Avoid redundant object evaluation in the ACPI device properties
     handling code (Heikki Krogerus).

   - Avoid unecessary memory overhead related to storing the signatures
     of the ACPI tables recognized by the kernel (Ard Biesheuvel).

   - Add missing newline characters when printing module parameter
     values in some places (Xiongfeng Wang).

   - Update the link to the ACPI specifications in some places (Tiezhu
     Yang).

   - Use the fallthrough pseudo-keyword in the ACPI code (Gustavo A. R.
     Silva).

   - Drop redundant variable initialization from the APEI code (Colin
     Ian King).

   - Drop uninitialized_var() from the ACPI PAD driver (Jason Yan).

   - Replace HTTP links with HTTPS ones in the ACPI code (Alexander A.
     Klimov)"

* tag 'acpi-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (22 commits)
  ACPI: APEI: remove redundant assignment to variable rc
  ACPI: NUMA: Remove the useless 'node >= MAX_NUMNODES' check
  ACPI: NUMA: Remove the useless sub table pointer check
  ACPI: tables: Remove the duplicated checks for acpi_parse_entries_array()
  ACPICA: Update version to 20200717
  ACPICA: Do not increment operation_region reference counts for field units
  ACPICA: Replace one-element array with flexible-array
  ACPI: Replace HTTP links with HTTPS ones
  ACPI: Use valid link to the ACPI specification
  ACPI: OSL: Clean up the removal of unused memory mappings
  ACPI: OSL: Use deferred unmapping in acpi_os_unmap_iomem()
  ACPI: OSL: Use deferred unmapping in acpi_os_unmap_generic_address()
  ACPICA: Preserve memory opregion mappings
  ACPI: OSL: Implement deferred unmapping of ACPI memory
  ACPI: Use fallthrough pseudo-keyword
  PCI: hotplug: ACPI: Fix context refcounting in acpiphp_grab_context()
  ACPI: tables: avoid relocations for table signature array
  ACPI: PAD: Eliminate usage of uninitialized_var() macro
  ACPI: sysfs: add newlines when printing module parameters
  ACPI: EC: add newline when printing 'ec_event_clearing' module parameter
  ...

1 files changed, 36 insertions, 27 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 762c5d50b8fe..6ad8cb05f672 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -77,7 +77,10 @@ struct acpi_ioremap {
 	void __iomem *virt;
 	acpi_physical_address phys;
 	acpi_size size;
-	unsigned long refcount;
+	union {
+		unsigned long refcount;
+		struct rcu_work rwork;
+	} track;
 };
 
 static LIST_HEAD(acpi_ioremaps);
@@ -250,7 +253,7 @@ void __iomem *acpi_os_get_iomem(acpi_physical_address phys, unsigned int size)
 	map = acpi_map_lookup(phys, size);
 	if (map) {
 		virt = map->virt + (phys - map->phys);
-		map->refcount++;
+		map->track.refcount++;
 	}
 	mutex_unlock(&acpi_ioremap_lock);
 	return virt;
@@ -335,7 +338,7 @@ void __iomem __ref
 	/* Check if there's a suitable mapping already. */
 	map = acpi_map_lookup(phys, size);
 	if (map) {
-		map->refcount++;
+		map->track.refcount++;
 		goto out;
 	}
 
@@ -358,7 +361,7 @@ void __iomem __ref
 	map->virt = virt;
 	map->phys = pg_off;
 	map->size = pg_sz;
-	map->refcount = 1;
+	map->track.refcount = 1;
 
 	list_add_tail_rcu(&map->list, &acpi_ioremaps);
 
@@ -374,21 +377,26 @@ void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);
 
-/* Must be called with mutex_lock(&acpi_ioremap_lock) */
-static unsigned long acpi_os_drop_map_ref(struct acpi_ioremap *map)
+static void acpi_os_map_remove(struct work_struct *work)
 {
-	unsigned long refcount = --map->refcount;
+	struct acpi_ioremap *map = container_of(to_rcu_work(work),
+						struct acpi_ioremap,
+						track.rwork);
 
-	if (!refcount)
-		list_del_rcu(&map->list);
-	return refcount;
+	acpi_unmap(map->phys, map->virt);
+	kfree(map);
 }
 
-static void acpi_os_map_cleanup(struct acpi_ioremap *map)
+/* Must be called with mutex_lock(&acpi_ioremap_lock) */
+static void acpi_os_drop_map_ref(struct acpi_ioremap *map)
 {
-	synchronize_rcu_expedited();
-	acpi_unmap(map->phys, map->virt);
-	kfree(map);
+	if (--map->track.refcount)
+		return;
+
+	list_del_rcu(&map->list);
+
+	INIT_RCU_WORK(&map->track.rwork, acpi_os_map_remove);
+	queue_rcu_work(system_wq, &map->track.rwork);
 }
 
 /**
@@ -397,8 +405,8 @@ static void acpi_os_map_cleanup(struct acpi_ioremap *map)
  * @size: Size of the address range to drop a reference to.
  *
  * Look up the given virtual address range in the list of existing ACPI memory
- * mappings, drop a reference to it and unmap it if there are no more active
- * references to it.
+ * mappings, drop a reference to it and if there are no more active references
+ * to it, queue it up for later removal.
  *
  * During early init (when acpi_permanent_mmap has not been set yet) this
  * routine simply calls __acpi_unmap_table() to get the job done.  Since
@@ -408,7 +416,6 @@ static void acpi_os_map_cleanup(struct acpi_ioremap *map)
 void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size)
 {
 	struct acpi_ioremap *map;
-	unsigned long refcount;
 
 	if (!acpi_permanent_mmap) {
 		__acpi_unmap_table(virt, size);
@@ -416,23 +423,27 @@ void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size)
 	}
 
 	mutex_lock(&acpi_ioremap_lock);
+
 	map = acpi_map_lookup_virt(virt, size);
 	if (!map) {
 		mutex_unlock(&acpi_ioremap_lock);
 		WARN(true, PREFIX "%s: bad address %p\n", __func__, virt);
 		return;
 	}
-	refcount = acpi_os_drop_map_ref(map);
-	mutex_unlock(&acpi_ioremap_lock);
+	acpi_os_drop_map_ref(map);
 
-	if (!refcount)
-		acpi_os_map_cleanup(map);
+	mutex_unlock(&acpi_ioremap_lock);
 }
 EXPORT_SYMBOL_GPL(acpi_os_unmap_iomem);
 
+/**
+ * acpi_os_unmap_memory - Drop a memory mapping reference.
+ * @virt: Start of the address range to drop a reference to.
+ * @size: Size of the address range to drop a reference to.
+ */
 void __ref acpi_os_unmap_memory(void *virt, acpi_size size)
 {
-	return acpi_os_unmap_iomem((void __iomem *)virt, size);
+	acpi_os_unmap_iomem((void __iomem *)virt, size);
 }
 EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
 
@@ -461,7 +472,6 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
 {
 	u64 addr;
 	struct acpi_ioremap *map;
-	unsigned long refcount;
 
 	if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		return;
@@ -472,16 +482,15 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas)
 		return;
 
 	mutex_lock(&acpi_ioremap_lock);
+
 	map = acpi_map_lookup(addr, gas->bit_width / 8);
 	if (!map) {
 		mutex_unlock(&acpi_ioremap_lock);
 		return;
 	}
-	refcount = acpi_os_drop_map_ref(map);
-	mutex_unlock(&acpi_ioremap_lock);
+	acpi_os_drop_map_ref(map);
 
-	if (!refcount)
-		acpi_os_map_cleanup(map);
+	mutex_unlock(&acpi_ioremap_lock);
 }
 EXPORT_SYMBOL(acpi_os_unmap_generic_address);