ACPI: Fix lockdep false positives in acpi_power_off()

All ACPICA locks are allocated by the same function,
acpi_os_create_lock(), with the help of a local variable called
"lock".  Thus, when lockdep is enabled, it uses "lock" as the
name of all those locks and regards them as instances of the same
lock, which causes it to report possible locking problems with them
when there aren't any.

To work around this problem, define acpi_os_create_lock() as a macro
and make it pass its argument to spin_lock_init(), so that lockdep
uses it as the name of the new lock.  Define this macron in a
Linux-specific file, to minimize the resulting modifications of
the OS-independent ACPICA parts.

This change is based on an earlier patch from Andrea Righi and it
addresses a regression from 2.6.39 tracked as
https://bugzilla.kernel.org/show_bug.cgi?id=38152

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-and-tested-by: Borislav Petkov <bp@alien8.de>
Tested-by: Andrea Righi <andrea@betterlinux.com>
Reviewed-by: Florian Mickler <florian@mickler.org>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 52ca9649d76925abc1718e9c3bed4391cf189006..372f9b70f7f4dc98e2985532fb19707861c920a8 100644 (file)
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1332,23 +1332,6 @@ int acpi_resources_are_enforced(void)
 }
 EXPORT_SYMBOL(acpi_resources_are_enforced);
 
-/*
- * Create and initialize a spinlock.
- */
-acpi_status
-acpi_os_create_lock(acpi_spinlock *out_handle)
-{
-       spinlock_t *lock;
-
-       lock = ACPI_ALLOCATE(sizeof(spinlock_t));
-       if (!lock)
-               return AE_NO_MEMORY;
-       spin_lock_init(lock);
-       *out_handle = lock;
-
-       return AE_OK;
-}
-
 /*
  * Deallocate the memory for a spinlock.
  */

diff --git a/include/acpi/acpiosxf.h b/include/acpi/acpiosxf.h
index a756bc8d866db15af5fbe3c2813e873b48aa48d7..4543b6f75867dfa4e6695e52e764cdd20c8f778d 100644 (file)
--- a/include/acpi/acpiosxf.h
+++ b/include/acpi/acpiosxf.h
@@ -98,8 +98,11 @@ acpi_os_table_override(struct acpi_table_header *existing_table,
 /*
  * Spinlock primitives
  */
+
+#ifndef acpi_os_create_lock
 acpi_status
 acpi_os_create_lock(acpi_spinlock *out_handle);
+#endif
 
 void acpi_os_delete_lock(acpi_spinlock handle);
 

diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
index 5d2a5e9544d9d4743202852cde379a60fb2f7600..2ce1be9f62918c38a52edf3d8424af1e4c48d25a 100644 (file)
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -159,6 +159,24 @@ static inline void *acpi_os_acquire_object(acpi_cache_t * cache)
        } while (0)
 #endif
 
+/*
+ * When lockdep is enabled, the spin_lock_init() macro stringifies it's
+ * argument and uses that as a name for the lock in debugging.
+ * By executing spin_lock_init() in a macro the key changes from "lock" for
+ * all locks to the name of the argument of acpi_os_create_lock(), which
+ * prevents lockdep from reporting false positives for ACPICA locks.
+ */
+#define acpi_os_create_lock(__handle)                          \
+({                                                             \
+       spinlock_t *lock = ACPI_ALLOCATE(sizeof(*lock));        \
+                                                               \
+       if (lock) {                                             \
+               *(__handle) = lock;                             \
+               spin_lock_init(*(__handle));                    \
+       }                                                       \
+       lock ? AE_OK : AE_NO_MEMORY;                            \
+})
+
 #endif /* __KERNEL__ */
 
 #endif /* __ACLINUX_H__ */