acpi/rt: Convert acpi_gbl_hardware lock back to a raw_spinlock_t

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
Cc: stable-rt@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

4 files changed, 7 insertions, 7 deletions

diff --git a/drivers/acpi/acpica/acglobal.h b/drivers/acpi/acpica/acglobal.h
index 90e846f..411f68d 100644
--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -235,7 +235,7 @@ ACPI_EXTERN u8 acpi_gbl_global_lock_pending;
  * interrupt level
  */
 ACPI_EXTERN acpi_spinlock acpi_gbl_gpe_lock;	/* For GPE data structs and registers */
-ACPI_EXTERN acpi_spinlock acpi_gbl_hardware_lock;	/* For ACPI H/W except GPE registers */
+ACPI_EXTERN acpi_raw_spinlock acpi_gbl_hardware_lock;	/* For ACPI H/W except GPE registers */
 ACPI_EXTERN acpi_spinlock acpi_gbl_reference_count_lock;
 
 /* Mutex for _OSI support */
diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c
index 8d2e866..221c567 100644
--- a/drivers/acpi/acpica/hwregs.c
+++ b/drivers/acpi/acpica/hwregs.c
@@ -269,14 +269,14 @@ acpi_status acpi_hw_clear_acpi_status(void)
 			  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;
diff --git a/drivers/acpi/acpica/hwxface.c b/drivers/acpi/acpica/hwxface.c
index 5ee7a81..4c4b0cc 100644
--- a/drivers/acpi/acpica/hwxface.c
+++ b/drivers/acpi/acpica/hwxface.c
@@ -365,7 +365,7 @@ acpi_status acpi_write_bit_register(u32 register_id, u32 value)
 		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
@@ -426,7 +426,7 @@ acpi_status acpi_write_bit_register(u32 register_id, u32 value)
 
 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);
 }
 
diff --git a/drivers/acpi/acpica/utmutex.c b/drivers/acpi/acpica/utmutex.c
index 08c3232..2f4ed8b 100644
--- a/drivers/acpi/acpica/utmutex.c
+++ b/drivers/acpi/acpica/utmutex.c
@@ -88,7 +88,7 @@ acpi_status acpi_ut_mutex_initialize(void)
 		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);
 	}
@@ -141,7 +141,7 @@ 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 */