Commit 835f14ed authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Make the TASKS_RCU Kconfig option be selected 



Currently, any kernel built with CONFIG_PREEMPTION=y also gets
CONFIG_TASKS_RCU=y, which is not helpful to people trying to build
preemptible kernels of minimal size.

Because CONFIG_TASKS_RCU=y is needed only in kernels doing tracing of
one form or another, this commit moves from TASKS_RCU deciding when it
should be enabled to the tracing Kconfig options explicitly selecting it.
This allows building preemptible kernels without TASKS_RCU, if desired.

This commit also updates the SRCU-N and TREE09 rcutorture scenarios
in order to avoid Kconfig errors that would otherwise result from
CONFIG_TASKS_RCU being selected without its CONFIG_RCU_EXPERT dependency
being met.

[ paulmck: Apply BPF_SYSCALL feedback from Andrii Nakryiko. ]

Reported-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: default avatarZhouyi Zhou <zhouzhouyi@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 46e861be

arch/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ config KPROBES 
	depends on MODULES

	depends on HAVE_KPROBES

	select KALLSYMS

	select TASKS_RCU if PREEMPTION

	help

	  Kprobes allows you to trap at almost any kernel address and

	  execute a callback function.  register_kprobe() establishes

kernel/bpf/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ config BPF_SYSCALL 
	bool "Enable bpf() system call"

	select BPF

	select IRQ_WORK

	select TASKS_RCU if PREEMPTION

	select TASKS_TRACE_RCU

	select BINARY_PRINTF

	select NET_SOCK_MSG if NET

kernel/rcu/Kconfig

+2 −1
Original line number Diff line number Diff line
@@ -78,7 +78,8 @@ config TASKS_RCU_GENERIC 
	  task-based RCU implementations.  Not for manual selection.



config TASKS_RCU

	def_bool PREEMPTION

	def_bool 0

	select IRQ_WORK

	help

	  This option enables a task-based RCU implementation that uses

	  only voluntary context switch (not preemption!), idle, and

kernel/trace/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -144,6 +144,7 @@ config TRACING 
	select BINARY_PRINTF

	select EVENT_TRACING

	select TRACE_CLOCK

	select TASKS_RCU if PREEMPTION



config GENERIC_TRACER

	bool

tools/testing/selftests/rcutorture/configs/rcu/SRCU-N

+2 −0
Original line number Diff line number Diff line
@@ -6,3 +6,5 @@ CONFIG_PREEMPT_NONE=y 
CONFIG_PREEMPT_VOLUNTARY=n

CONFIG_PREEMPT=n

#CHECK#CONFIG_RCU_EXPERT=n

CONFIG_KPROBES=n

CONFIG_FTRACE=n