From: Steven Rostedt <rostedt@goodmis.org>
Date: Wed, 13 Feb 2013 09:26:05 -0500
Subject: acpi/rt: Convert acpi_gbl_hardware lock back to a raw_spinlock_t
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.6/older/patches-4.6.2-rt5.tar.xz

We hit the following bug with 3.6-rt:

[    5.898990] BUG: scheduling while atomic: swapper/3/0/0x00000002
[    5.898991] no locks held by swapper/3/0.
[    5.898993] Modules linked in:
[    5.898996] Pid: 0, comm: swapper/3 Not tainted 3.6.11-rt28.19.el6rt.x86_64.debug #1
[    5.898997] Call Trace:
[    5.899011]  [<ffffffff810804e7>] __schedule_bug+0x67/0x90
[    5.899028]  [<ffffffff81577923>] __schedule+0x793/0x7a0
[    5.899032]  [<ffffffff810b4e40>] ? debug_rt_mutex_print_deadlock+0x50/0x200
[    5.899034]  [<ffffffff81577b89>] schedule+0x29/0x70
[    5.899036] BUG: scheduling while atomic: swapper/7/0/0x00000002
[    5.899037] no locks held by swapper/7/0.
[    5.899039]  [<ffffffff81578525>] rt_spin_lock_slowlock+0xe5/0x2f0
[    5.899040] Modules linked in:
[    5.899041]
[    5.899045]  [<ffffffff81579a58>] ? _raw_spin_unlock_irqrestore+0x38/0x90
[    5.899046] Pid: 0, comm: swapper/7 Not tainted 3.6.11-rt28.19.el6rt.x86_64.debug #1
[    5.899047] Call Trace:
[    5.899049]  [<ffffffff81578bc6>] rt_spin_lock+0x16/0x40
[    5.899052]  [<ffffffff810804e7>] __schedule_bug+0x67/0x90
[    5.899054]  [<ffffffff8157d3f0>] ? notifier_call_chain+0x80/0x80
[    5.899056]  [<ffffffff81577923>] __schedule+0x793/0x7a0
[    5.899059]  [<ffffffff812f2034>] acpi_os_acquire_lock+0x1f/0x23
[    5.899062]  [<ffffffff810b4e40>] ? debug_rt_mutex_print_deadlock+0x50/0x200
[    5.899068]  [<ffffffff8130be64>] acpi_write_bit_register+0x33/0xb0
[    5.899071]  [<ffffffff81577b89>] schedule+0x29/0x70
[    5.899072]  [<ffffffff8130be13>] ? acpi_read_bit_register+0x33/0x51
[    5.899074]  [<ffffffff81578525>] rt_spin_lock_slowlock+0xe5/0x2f0
[    5.899077]  [<ffffffff8131d1fc>] acpi_idle_enter_bm+0x8a/0x28e
[    5.899079]  [<ffffffff81579a58>] ? _raw_spin_unlock_irqrestore+0x38/0x90
[    5.899081]  [<ffffffff8107e5da>] ? this_cpu_load+0x1a/0x30
[    5.899083]  [<ffffffff81578bc6>] rt_spin_lock+0x16/0x40
[    5.899087]  [<ffffffff8144c759>] cpuidle_enter+0x19/0x20
[    5.899088]  [<ffffffff8157d3f0>] ? notifier_call_chain+0x80/0x80
[    5.899090]  [<ffffffff8144c777>] cpuidle_enter_state+0x17/0x50
[    5.899092]  [<ffffffff812f2034>] acpi_os_acquire_lock+0x1f/0x23
[    5.899094]  [<ffffffff8144d1a1>] cpuidle899101]  [<ffffffff8130be13>] ?

As the acpi code disables interrupts in acpi_idle_enter_bm, and calls
code that grabs the acpi lock, it causes issues as the lock is currently
in RT a sleeping lock.

The lock was converted from a raw to a sleeping lock due to some
previous issues, and tests that showed it didn't seem to matter.
Unfortunately, it did matter for one of our boxes.

This patch converts the lock back to a raw lock. I've run this code on a
few of my own machines, one being my laptop that uses the acpi quite
extensively. I've been able to suspend and resume without issues.

[ tglx: Made the change exclusive for acpi_gbl_hardware_lock ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: John Kacur <jkacur@gmail.com>
Cc: Clark Williams <clark@redhat.com>
Link: http://lkml.kernel.org/r/1360765565.23152.5.camel@gandalf.local.home

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/acpi/acpica/acglobal.h  |    2 +-
 drivers/acpi/acpica/hwregs.c    |    4 ++--
 drivers/acpi/acpica/hwxface.c   |    4 ++--
 drivers/acpi/acpica/utmutex.c   |    4 ++--
 include/acpi/platform/aclinux.h |   15 +++++++++++++++
 5 files changed, 22 insertions(+), 7 deletions(-)

--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -116,7 +116,7 @@ ACPI_GLOBAL(u8, acpi_gbl_global_lock_pen
  * interrupt level
  */
 ACPI_GLOBAL(acpi_spinlock, acpi_gbl_gpe_lock);	/* For GPE data structs and registers */
-ACPI_GLOBAL(acpi_spinlock, acpi_gbl_hardware_lock);	/* For ACPI H/W except GPE registers */
+ACPI_GLOBAL(acpi_raw_spinlock, acpi_gbl_hardware_lock);	/* For ACPI H/W except GPE registers */
 ACPI_GLOBAL(acpi_spinlock, acpi_gbl_reference_count_lock);
 
 /* Mutex for _OSI support */
--- a/drivers/acpi/acpica/hwregs.c
+++ b/drivers/acpi/acpica/hwregs.c
@@ -269,14 +269,14 @@ acpi_status acpi_hw_clear_acpi_status(vo
 			  ACPI_BITMASK_ALL_FIXED_STATUS,
 			  ACPI_FORMAT_UINT64(acpi_gbl_xpm1a_status.address)));
 
-	lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
+	raw_spin_lock_irqsave(acpi_gbl_hardware_lock, lock_flags);
 
 	/* Clear the fixed events in PM1 A/B */
 
 	status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
 					ACPI_BITMASK_ALL_FIXED_STATUS);
 
-	acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
+	raw_spin_unlock_irqrestore(acpi_gbl_hardware_lock, lock_flags);
 
 	if (ACPI_FAILURE(status)) {
 		goto exit;
--- a/drivers/acpi/acpica/hwxface.c
+++ b/drivers/acpi/acpica/hwxface.c
@@ -374,7 +374,7 @@ acpi_status acpi_write_bit_register(u32
 		return_ACPI_STATUS(AE_BAD_PARAMETER);
 	}
 
-	lock_flags = acpi_os_acquire_lock(acpi_gbl_hardware_lock);
+	raw_spin_lock_irqsave(acpi_gbl_hardware_lock, lock_flags);
 
 	/*
 	 * At this point, we know that the parent register is one of the
@@ -435,7 +435,7 @@ acpi_status acpi_write_bit_register(u32
 
 unlock_and_exit:
 
-	acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
+	raw_spin_unlock_irqrestore(acpi_gbl_hardware_lock, lock_flags);
 	return_ACPI_STATUS(status);
 }
 
--- a/drivers/acpi/acpica/utmutex.c
+++ b/drivers/acpi/acpica/utmutex.c
@@ -88,7 +88,7 @@ acpi_status acpi_ut_mutex_initialize(voi
 		return_ACPI_STATUS (status);
 	}
 
-	status = acpi_os_create_lock (&acpi_gbl_hardware_lock);
+	status = acpi_os_create_raw_lock (&acpi_gbl_hardware_lock);
 	if (ACPI_FAILURE (status)) {
 		return_ACPI_STATUS (status);
 	}
@@ -145,7 +145,7 @@ void acpi_ut_mutex_terminate(void)
 	/* Delete the spinlocks */
 
 	acpi_os_delete_lock(acpi_gbl_gpe_lock);
-	acpi_os_delete_lock(acpi_gbl_hardware_lock);
+	acpi_os_delete_raw_lock(acpi_gbl_hardware_lock);
 	acpi_os_delete_lock(acpi_gbl_reference_count_lock);
 
 	/* Delete the reader/writer lock */
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -127,6 +127,7 @@
 
 #define acpi_cache_t                        struct kmem_cache
 #define acpi_spinlock                       spinlock_t *
+#define acpi_raw_spinlock		raw_spinlock_t *
 #define acpi_cpu_flags                      unsigned long
 
 /* Use native linux version of acpi_os_allocate_zeroed */
@@ -145,6 +146,20 @@
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_get_thread_id
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_create_lock
 
+#define acpi_os_create_raw_lock(__handle)			\
+({								\
+	 raw_spinlock_t *lock = ACPI_ALLOCATE(sizeof(*lock));	\
+								\
+	 if (lock) {						\
+		*(__handle) = lock;				\
+		raw_spin_lock_init(*(__handle));		\
+	 }							\
+	 lock ? AE_OK : AE_NO_MEMORY;				\
+ })
+
+#define acpi_os_delete_raw_lock(__handle)	kfree(__handle)
+
+
 /*
  * OSL interfaces used by debugger/disassembler
  */
