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: Ingo Molnar <mingo@kernel.org>

4 files changed, 16 insertions, 2 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index af2cc6eabcc7..185f8b007643 100644
--- a/arch/Kconfig
+++ b/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
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1ad6fb6c094d..323baf07fdce 100644
--- a/arch/arm/Kconfig
+++ b/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
diff --git a/init/Kconfig b/init/Kconfig
index 3ecd8a1178f1..841e79cb8bb3 100644
--- a/init/Kconfig
+++ b/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
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 2b62fe86f9ec..3ce6e8c5f3fc 100644
--- a/kernel/time/Kconfig
+++ b/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