Merge branch 'timers/core' of...

Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core

Merge updated full dynticks support from Frederic Weisbecker:

   - support 32-bit systems (full dynticks was 64-bit only before)
   - support ARM
Signed-off-by: NIngo Molnar <mingo@kernel.org>

arch/Kconfig

@@ -353,6 +353,18 @@ config HAVE_CONTEXT_TRACKING
 config HAVE_VIRT_CPU_ACCOUNTING
 	bool
 
+config HAVE_VIRT_CPU_ACCOUNTING_GEN
+	bool
+	default y if 64BIT
+	help
+	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
+	  Before enabling this option, arch code must be audited
+	  to ensure there are no races in concurrent read/write of
+	  cputime_t. For example, reading/writing 64-bit cputime_t on
+	  some 32-bit arches may require multiple accesses, so proper
+	  locking is needed to protect against concurrent accesses.
+
+
 config HAVE_IRQ_TIME_ACCOUNTING
 	bool
 	help

arch/arm/Kconfig

@@ -54,6 +54,7 @@ config ARM
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_UID16
+	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select IRQ_FORCED_THREADING
 	select KTIME_SCALAR
 	select MODULES_USE_ELF_REL

init/Kconfig

@@ -354,7 +354,8 @@ config VIRT_CPU_ACCOUNTING_NATIVE
 
 config VIRT_CPU_ACCOUNTING_GEN
 	bool "Full dynticks CPU time accounting"
-	depends on HAVE_CONTEXT_TRACKING && 64BIT
+	depends on HAVE_CONTEXT_TRACKING
+	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select VIRT_CPU_ACCOUNTING
 	select CONTEXT_TRACKING
 	help

kernel/time/Kconfig

@@ -100,7 +100,7 @@ config NO_HZ_FULL
 	# RCU_USER_QS dependency
 	depends on HAVE_CONTEXT_TRACKING
 	# VIRT_CPU_ACCOUNTING_GEN dependency
-	depends on 64BIT
+	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select NO_HZ_COMMON
 	select RCU_USER_QS
 	select RCU_NOCB_CPU