[PATCH tip/core/rcu 05/18] Default enable RCU list lockdep debugging with PROVE_RCU

paulmck
2020-04-15T17:31:20Z

From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>

This patch default enables CONFIG_PROVE_RCU_LIST option with
CONFIG_PROVE_RCU for RCU list lockdep debugging.

With this change, RCU list lockdep debugging will be default
enabled in CONFIG_PROVE_RCU=y kernels.

Most of the RCU users (in core kernel/, drivers/, and net/
subsystem) have already been modified to include lockdep
expressions hence RCU list debugging can be enabled by
default.

However, there are still chances of enountering
false-positive lockdep splats because not everything is converted,
in case RCU list primitives are used in non-RCU read-side critical
section but under the protection of a lock. It would be okay to
have a few false-positives, as long as bugs are identified, since this
patch only affects debugging kernels.

Co-developed-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/Kconfig.debug | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 4aa02ee..ec4bb6c 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -9,15 +9,10 @@ config PROVE_RCU
def_bool PROVE_LOCKING

config PROVE_RCU_LIST
- bool "RCU list lockdep debugging"
- depends on PROVE_RCU && RCU_EXPERT
- default n
+ def_bool PROVE_RCU
help
- Enable RCU lockdep checking for list usages. By default it is
- turned off since there are several list RCU users that still
- need to be converted to pass a lockdep expression. To prevent
- false-positive splats, we keep it default disabled but once all
- users are converted, we can remove this config option.
+ Enable RCU lockdep checking for list usages. It is default
+ enabled with CONFIG_PROVE_RCU.

config TORTURE_TEST
tristate
--
2.9.5