lockref: use BLOATED_SPINLOCKS to avoid explicit config dependencies

Avoid the fragile Kconfig construct guestimating spinlock_t sizes; use a
friendly compile-time test to determine this.

[kirill.shutemov@linux.intel.com: drop CONFIG_CMPXCHG_LOCKREF]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/lockref.h

@@ -15,10 +15,15 @@
  */
 
 #include <linux/spinlock.h>
+#include <generated/bounds.h>
+
+#define USE_CMPXCHG_LOCKREF \
+	(IS_ENABLED(CONFIG_ARCH_USE_CMPXCHG_LOCKREF) && \
+	 IS_ENABLED(CONFIG_SMP) && !BLOATED_SPINLOCKS)
 
 struct lockref {
 	union {
-#ifdef CONFIG_CMPXCHG_LOCKREF
+#if USE_CMPXCHG_LOCKREF
 		aligned_u64 lock_count;
 #endif
 		struct {

lib/Kconfig

@@ -51,13 +51,6 @@ config PERCPU_RWSEM
 config ARCH_USE_CMPXCHG_LOCKREF
 	bool
 
-config CMPXCHG_LOCKREF
-	def_bool y if ARCH_USE_CMPXCHG_LOCKREF
-	depends on SMP
-	depends on !GENERIC_LOCKBREAK
-	depends on !DEBUG_SPINLOCK
-	depends on !DEBUG_LOCK_ALLOC
-
 config CRC_CCITT
 	tristate "CRC-CCITT functions"
 	help

lib/lockref.c

@@ -1,7 +1,7 @@
 #include <linux/export.h>
 #include <linux/lockref.h>
 
-#ifdef CONFIG_CMPXCHG_LOCKREF
+#if USE_CMPXCHG_LOCKREF
 
 /*
  * Allow weakly-ordered memory architectures to provide barrier-less