rcu: Disable TASKS_RCU for usermode Linux

Usermode Linux currently does not implement arch_irqs_disabled_flags(),
which results in a build failure in TASKS_RCU.  Therefore, this commit
disables the TASKS_RCU Kconfig option in usermode Linux builds.  The
usermode Linux maintainers expect to merge arch_irqs_disabled_flags()
into 4.8, at which point this commit may be reverted.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jeff Dike <jdike@addtoit.com>
Acked-by: Richard Weinberger <richard@nod.at>

1 files changed, 1 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index f755a602d4a1..a068265fbcaf 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -517,6 +517,7 @@ config SRCU
 config TASKS_RCU
         bool
         default n
+        depends on !UML
         select SRCU
         help
           This option enables a task-based RCU implementation that uses