From 835f14ed53076384f0e1dad2fddb4881315f124f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 17 Mar 2022 11:05:09 -0700 Subject: 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: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Zhouyi Zhou Cc: Andrii Nakryiko Cc: Alexei Starovoitov Cc: Steven Rostedt Cc: Mathieu Desnoyers Acked-by: Masami Hiramatsu Signed-off-by: Paul E. McKenney --- kernel/bpf/Kconfig | 1 + kernel/rcu/Kconfig | 3 ++- kernel/trace/Kconfig | 1 + 3 files changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig index d56ee177d5f8..2dfe1079f772 100644 --- a/kernel/bpf/Kconfig +++ b/kernel/bpf/Kconfig @@ -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 diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index f559870fbf8b..4f665ae0cf55 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -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 diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 2c43e327a619..bf5da6c4e999 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -144,6 +144,7 @@ config TRACING select BINARY_PRINTF select EVENT_TRACING select TRACE_CLOCK + select TASKS_RCU if PREEMPTION config GENERIC_TRACER bool -- cgit v1.2.3