Merge branch 'sparc-lockdep-small'

Babu Moger says:

====================
Adjust lockdep static allocations for sparc

These patches limit the static allocations for lockdep data structures
used for debugging locking correctness. For sparc, all the kernel's code,
data, and bss, must have locked translations in the TLB so that we don't
get TLB misses on kernel code and data. Current sparc chips have 8 TLB
entries available that may be locked down, and with a 4mb page size,
this gives a maximum of 32MB. With PROVE_LOCKING we could go over this
limit and cause system boot-up problems. These patches limit the static
allocations so that everything fits in current required size limit.

patch 1 : Adds new config parameter CONFIG_PROVE_LOCKING_SMALL
Patch 2 : Adjusts the sizes based on the new config parameter

v2-> v3:
   Some more comments from Sam Ravnborg and Peter Zijlstra.
   Defined PROVE_LOCKING_SMALL as invisible and moved the selection to
   arch/sparc/Kconfig.

v1-> v2:
   As suggested by Peter Zijlstra, keeping the default as is.
   Introduced new config variable CONFIG_PROVE_LOCKING_SMALL
   to handle sparc specific case.

v0:
   Initial revision.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/Kconfig

@@ -43,6 +43,7 @@ config SPARC
 	select ARCH_HAS_SG_CHAIN
 	select CPU_NO_EFFICIENT_FFS
 	select HAVE_ARCH_HARDENED_USERCOPY
+	select PROVE_LOCKING_SMALL if PROVE_LOCKING
 
 config SPARC32
 	def_bool !64BIT

kernel/locking/lockdep_internals.h

@@ -45,6 +45,14 @@ enum {
 #define LOCKF_USED_IN_IRQ_READ \
 		(LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
 
+/*
+ * CONFIG_PROVE_LOCKING_SMALL is defined for sparc. Sparc requires .text,
+ * .data and .bss to fit in required 32MB limit for the kernel. With
+ * PROVE_LOCKING we could go over this limit and cause system boot-up problems.
+ * So, reduce the static allocations for lockdeps related structures so that
+ * everything fits in current required size limit.
+ */
+#ifdef CONFIG_PROVE_LOCKING_SMALL
 /*
  * MAX_LOCKDEP_ENTRIES is the maximum number of lock dependencies
  * we track.
@@ -54,18 +62,24 @@ enum {
  * table (if it's not there yet), and we check it for lock order
  * conflicts and deadlocks.
  */
+#define MAX_LOCKDEP_ENTRIES	16384UL
+#define MAX_LOCKDEP_CHAINS_BITS	15
+#define MAX_STACK_TRACE_ENTRIES	262144UL
+#else
 #define MAX_LOCKDEP_ENTRIES	32768UL
 
 #define MAX_LOCKDEP_CHAINS_BITS	16
-#define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
-
-#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
 
 /*
  * Stack-trace: tightly packed array of stack backtrace
  * addresses. Protected by the hash_lock.
  */
 #define MAX_STACK_TRACE_ENTRIES	524288UL
+#endif
+
+#define MAX_LOCKDEP_CHAINS	(1UL << MAX_LOCKDEP_CHAINS_BITS)
+
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
 
 extern struct list_head all_lock_classes;
 extern struct lock_chain lock_chains[];

lib/Kconfig.debug

@@ -1085,6 +1085,9 @@ config PROVE_LOCKING
 
 	 For more details, see Documentation/locking/lockdep-design.txt.
 
+config PROVE_LOCKING_SMALL
+	bool
+
 config LOCKDEP
 	bool
 	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT