On Mon, 18 Apr 2022 17:12:23 -0700 "Paul E. McKenney" <paulmck@xxxxxxxxxx> wrote: > 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. Thanks for fixing this dependency. This looks good to me (for kprobe part) Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Thank you, > > [ paulmck: Apply BPF_SYSCALL feedback from Andrii Nakryiko. ] > > Reported-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> > Tested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> > Tested-by: Zhouyi Zhou <zhouzhouyi@xxxxxxxxx> > Cc: Andrii Nakryiko <andrii@xxxxxxxxxx> > Cc: Alexei Starovoitov <ast@xxxxxxxxxx> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > > --- Update SRCU-N and TREE09 to avoid Kconfig errors. > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > --- > arch/Kconfig | 1 + > kernel/bpf/Kconfig | 1 + > kernel/rcu/Kconfig | 3 ++- > kernel/trace/Kconfig | 1 + > tools/testing/selftests/rcutorture/configs/rcu/SRCU-N | 2 ++ > tools/testing/selftests/rcutorture/configs/rcu/TREE09 | 2 ++ > 6 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 29b0167c088b..1bf29ce754af 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -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 > 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 > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N > index 2da8b49589a0..07f5e0a70ae7 100644 > --- a/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N > +++ b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N > @@ -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 > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE09 b/tools/testing/selftests/rcutorture/configs/rcu/TREE09 > index 8523a7515cbf..fc45645bb5f4 100644 > --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE09 > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE09 > @@ -13,3 +13,5 @@ CONFIG_DEBUG_LOCK_ALLOC=n > CONFIG_RCU_BOOST=n > CONFIG_DEBUG_OBJECTS_RCU_HEAD=n > #CHECK#CONFIG_RCU_EXPERT=n > +CONFIG_KPROBES=n > +CONFIG_FTRACE=n > -- > 2.31.1.189.g2e36527f23 > -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
