Patch "ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic table loading ACPICA: Add per-table execution of module-level code" has been added to the 4.6-stable tree

From 2f38b1b16d9280689e5cfa47a4c50956bf437f0d Mon Sep 17 00:00:00 2001

From: [email protected] [mailto:[email protected]]
Subject: Patch "ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic table loading ACPICA: Add per-table execution of module-level code" has been added to the 4.6-stable tree

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

ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic
table loading
ACPICA: Add per-table execution of module-level code

to the 4.6-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:
acpica-namespace-fix-deadlock-triggered-by-mlc-support-in-dynamic-
table-loading.patch
and it can be found in the queue-4.6 subdirectory.

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

From 2f38b1b16d9280689e5cfa47a4c50956bf437f0d Mon Sep 17 00:00:00 2001
From: Lv Zheng <[email protected]>
Date: Tue, 21 Jun 2016 12:34:15 +0800
Subject: ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic table loading

From: Lv Zheng <[email protected]>

commit 2f38b1b16d9280689e5cfa47a4c50956bf437f0d upstream.

The new module-level code (MLC) approach invokes MLC on the per-table basis, but the dynamic loading support of this is incorrect because of the lock order:

acpi_ns_evaluate
acpi_ex_enter_intperter
acpi_ns_load_table (triggered by Load opcode)
acpi_ns_exec_module_code_list
acpi_ex_enter_intperter

The regression is introduced by the following commit:

Commit: 2785ce8d0da1cac9d8f78615e116cf929e9a9123 ACPICA Commit: 071eff738c59eda1792ac24b3b688b61691d7e7c
Subject: ACPICA: Add per-table execution of module-level code

This patch fixes this regression by unlocking the interpreter lock before invoking MLC. However, the unlocking is done to the acpi_ns_load_table(), in which the interpreter lock should be locked by acpi_ns_parse_table() but it wasn't.

Fixes 2785ce8d0da1 (ACPICA: Add per-table execution of module-level

code)

Reported-by Mika Westerberg <[email protected]>

Tested-by Mika Westerberg <[email protected]>

Signed-off-by Lv Zheng <[email protected]>

[ rjw : Subject ]

Signed-off-by Rafael J. Wysocki <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/acpi/acpica/exconfig.c |    2 ++
 drivers/acpi/acpica/nsparse.c  |    9 +++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

drivers/acpi/acpica/exconfig.c +2 -0

@@ -108,7 +108,9 @@ acpi_ex_add_table(u32 table_index,
 
 	/* Add the table to the namespace */
 
+	acpi_ex_exit_interpreter();
 	status = acpi_ns_load_table(table_index, parent_node);
+	acpi_ex_enter_interpreter();
 	if (ACPI_FAILURE(status)) {
 		acpi_ut_remove_reference(obj_desc);
 		*ddb_handle = NULL;

drivers/acpi/acpica/nsparse.c +7 -2

@@ -47,6 +47,7 @@
 #include "acparser.h"
 #include "acdispat.h"
 #include "actables.h"
+#include "acinterp.h"
 
 #define _COMPONENT          ACPI_NAMESPACE
 ACPI_MODULE_NAME("nsparse")

@@ -170,6 +171,8 @@ acpi_ns_parse_table(u32 table_index, str
 
 	ACPI_FUNCTION_TRACE(ns_parse_table);
 
+	acpi_ex_enter_interpreter();
+
 	/*
 	 * AML Parse, pass 1
 	 *

@@ -185,7 +188,7 @@ acpi_ns_parse_table(u32 table_index, str
 	status = acpi_ns_one_complete_parse(ACPI_IMODE_LOAD_PASS1,
 					    table_index, start_node);
 	if (ACPI_FAILURE(status)) {
-		return_ACPI_STATUS(status);
+		goto error_exit;
 	}
 
 	/*

@@ -201,8 +204,10 @@ acpi_ns_parse_table(u32 table_index, str
 	status = acpi_ns_one_complete_parse(ACPI_IMODE_LOAD_PASS2,
 					    table_index, start_node);
 	if (ACPI_FAILURE(status)) {
-		return_ACPI_STATUS(status);
+		goto error_exit;
 	}
 
+error_exit:
+	acpi_ex_exit_interpreter();
 	return_ACPI_STATUS(status);
 }

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

queue-4.6/acpica-namespace-fix-deadlock-triggered-by-mlc-support-in- dynamic-table-loading.patch

Hi, Greg

Quoted 11 lines

From: [email protected] [mailto:[email protected]]
Subject: Patch "ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic table loading ACPICA: Add per-table execution of module-level code" has been added to the 4.6-stable tree

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

ACPICA: Namespace: Fix deadlock triggered by MLC support in dynamic
table loading
ACPICA: Add per-table execution of module-level code

[Lv Zheng]
The issue cannot be fixed by such a simple change.
It finally triggered many namespace locking issues in ACPICA and required big changes. I'm waiting for ACPICA upstream's confirmation for another fix proposal. And this fix is reverted from the Linux upstream during this period:
https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?id=ffd8d618

Here is the sotry for your reference:
https://bugzilla.kernel.org/show_bug.cgi?id=121701

Please do not make this commit a stable material.
Sorry for the problem.