Patch "ACPI / PNP: Reserve ACPI resources at the fs_initcall_sync stage" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

ACPI / PNP: Reserve ACPI resources at the fs_initcall_sync stage

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
acpi-pnp-reserve-acpi-resources-at-the-fs_initcall_sync-stage.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Rafael J. Wysocki" <[email protected]>
Date: Sat, 4 Jul 2015 03:09:03 +0200
Subject: ACPI / PNP: Reserve ACPI resources at the fs_initcall_sync stage

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

commit 0294112ee3135fbd15eaa70015af8283642dd970 upstream.

This effectively reverts the following three commits:

7bc10388ccdd ACPI / resources: free memory on error in add_region_before() 0f1b414d1907 ACPI / PNP: Avoid conflicting resource reservations b9a5e5e18fbf ACPI / init: Fix the ordering of acpi_reserve_resources()

(commit b9a5e5e18fbf introduced regressions some of which, but not all, were addressed by commit 0f1b414d1907 and commit 7bc10388ccdd was a fixup on top of the latter) and causes ACPI fixed hardware resources to be reserved at the fs_initcall_sync stage of system initialization.

The story is as follows. First, a boot regression was reported due to an apparent resource reservation ordering change after a commit that shouldn't lead to such changes. Investigation led to the conclusion that the problem happened because acpi_reserve_resources() was executed at the device_initcall() stage of system initialization which wasn't strictly ordered with respect to driver initialization (and with respect to the initialization of the pcieport driver in particular), so a random change causing the device initcalls to be run in a different order might break things.

The response to that was to attempt to run acpi_reserve_resources() as soon as we knew that ACPI would be in use (commit b9a5e5e18fbf). However, that turned out to be too early, because it caused resource reservations made by the PNP system driver to fail on at least one system and that failure was addressed by commit 0f1b414d1907.

That fix still turned out to be insufficient, though, because calling acpi_reserve_resources() before the fs_initcall stage of system initialization caused a boot regression to happen on the eCAFE EC-800-H20G/S netbook. That meant that we only could call acpi_reserve_resources() at the fs_initcall initialization stage or later, but then we might just as well call it after the PNP initalization in which case commit 0f1b414d1907 wouldn't be necessary any more.

For this reason, the changes made by commit 0f1b414d1907 are reverted (along with a memory leak fixup on top of that commit), the changes made by commit b9a5e5e18fbf that went too far are reverted too and acpi_reserve_resources() is changed into fs_initcall_sync, which will cause it to be executed after the PNP subsystem initialization (which is an fs_initcall) and before device initcalls (including the pcieport driver initialization) which should avoid the initial issue.

---
 drivers/acpi/osl.c      |   12 ++-
 drivers/acpi/resource.c |  162 ------------------------------------------------
 drivers/pnp/system.c    |   35 ++--------
 include/linux/acpi.h    |   10 --
 4 files changed, 18 insertions(+), 201 deletions(-)

@@ -175,10 +175,14 @@ static void __init acpi_request_region (
 	if (!addr || !length)
 		return;
 
-	acpi_reserve_region(addr, length, gas->space_id, 0, desc);
+	/* 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);
 }
 
-static void __init acpi_reserve_resources(void)
+static int __init acpi_reserve_resources(void)
 {
 	acpi_request_region(&acpi_gbl_FADT.xpm1a_event_block, acpi_gbl_FADT.pm1_event_length,
 		"ACPI PM1a_EVT_BLK");

@@ -207,7 +211,10 @@ static void __init acpi_reserve_resource
 	if (!(acpi_gbl_FADT.gpe1_block_length & 0x1))
 		acpi_request_region(&acpi_gbl_FADT.xgpe1_block,
 			       acpi_gbl_FADT.gpe1_block_length, "ACPI GPE1_BLK");
+
+	return 0;
 }
+fs_initcall_sync(acpi_reserve_resources);
 
 void acpi_os_printf(const char *fmt, ...)
 {

@@ -1838,7 +1845,6 @@ acpi_status __init acpi_os_initialize(vo
 
 acpi_status __init acpi_os_initialize1(void)
 {
-	acpi_reserve_resources();
 	kacpid_wq = alloc_workqueue("kacpid", 0, 1);
 	kacpi_notify_wq = alloc_workqueue("kacpi_notify", 0, 1);
 	kacpi_hotplug_wq = alloc_ordered_workqueue("kacpi_hotplug", 0);

@@ -7,7 +7,6 @@
  *	Bjorn Helgaas <[email protected]>
  */
 
-#include <linux/acpi.h>
 #include <linux/pnp.h>
 #include <linux/device.h>
 #include <linux/init.h>

@@ -23,41 +22,25 @@ static const struct pnp_device_id pnp_de
 	{"", 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;
-	bool reserved;
+	struct resource *res;
 
 	regionid = kmalloc(16, GFP_KERNEL);
 	if (!regionid)
 		return;
 
 	snprintf(regionid, 16, "pnp %s", pnpid);
-	reserved = __reserve_range(start, end - start + 1, !!port, regionid);
-	if (!reserved)
+	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
 		kfree(regionid);
 
 	/*

@@ -66,7 +49,7 @@ static void reserve_range(struct pnp_dev
 	 * have double reservations.
 	 */
 	dev_info(&dev->dev, "%pR %s reserved\n", r,
-		 reserved ? "has been" : "could not be");
+		 res ? "has been" : "could not be");
 }
 
 static void reserve_resources_of_dev(struct pnp_dev *dev)

@@ -332,9 +332,6 @@ int acpi_check_region(resource_size_t st
 
 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

@@ -530,13 +527,6 @@ static inline int acpi_check_region(reso
 	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 *))

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/acpi-pci-fix-regressions-caused-by-resource_size_t-overflow-with-32-bit-kernel.patch queue-4.1/acpica-tables-fix-an-issue-that-facs-initialization-is-performed-twice.patch queue-4.1/acpi-lpss-fix-up-acpi_lpss_create_device.patch queue-4.1/acpi-pnp-reserve-acpi-resources-at-the-fs_initcall_sync-stage.patch queue-4.1/acpi-resources-free-memory-on-error-in-add_region_before.patch queue-4.1/acpica-tables-enable-default-64-bit-fadt-addresses-favor.patch queue-4.1/acpica-tables-enable-both-32-bit-and-64-bit-facs.patch