Re: [PATCH v3 06/22] rcu: Rename rcu_irq_{enter,exit}_irqson()

Paul E. McKenney
2020-02-19T16:38:03Z

On Wed, Feb 19, 2020 at 03:47:30PM +0100, Peter Zijlstra wrote:
> The functions do in fact use local_irq_{save,restore}() and can
> therefore be used when IRQs are in fact disabled. Worse, they are
> already used in places where IRQs are disabled, leading to great
> confusion when reading the code.
>
> Rename them to fix this confusion.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

My first reaction was "Hey, wait, where is the _irqrestore()?"

Nevertheless, especially since these are the only _irqson() functions:

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

> ---
> include/linux/rcupdate.h | 4 ++--
> include/linux/rcutiny.h | 4 ++--
> include/linux/rcutree.h | 4 ++--
> include/linux/tracepoint.h | 4 ++--
> kernel/cpu_pm.c | 4 ++--
> kernel/rcu/tree.c | 8 ++++----
> kernel/trace/trace.c | 4 ++--
> 7 files changed, 16 insertions(+), 16 deletions(-)
>
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -120,9 +120,9 @@ static inline void rcu_init_nohz(void) {
> */
> #define RCU_NONIDLE(a) \
> do { \
> - rcu_irq_enter_irqson(); \
> + rcu_irq_enter_irqsave(); \
> do { a; } while (0); \
> - rcu_irq_exit_irqson(); \
> + rcu_irq_exit_irqsave(); \
> } while (0)
>
> /*
> --- a/include/linux/rcutiny.h
> +++ b/include/linux/rcutiny.h
> @@ -68,8 +68,8 @@ static inline int rcu_jiffies_till_stall
> static inline void rcu_idle_enter(void) { }
> static inline void rcu_idle_exit(void) { }
> static inline void rcu_irq_enter(void) { }
> -static inline void rcu_irq_exit_irqson(void) { }
> -static inline void rcu_irq_enter_irqson(void) { }
> +static inline void rcu_irq_exit_irqsave(void) { }
> +static inline void rcu_irq_enter_irqsave(void) { }
> static inline void rcu_irq_exit(void) { }
> static inline void exit_rcu(void) { }
> static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
> --- a/include/linux/rcutree.h
> +++ b/include/linux/rcutree.h
> @@ -46,8 +46,8 @@ void rcu_idle_enter(void);
> void rcu_idle_exit(void);
> void rcu_irq_enter(void);
> void rcu_irq_exit(void);
> -void rcu_irq_enter_irqson(void);
> -void rcu_irq_exit_irqson(void);
> +void rcu_irq_enter_irqsave(void);
> +void rcu_irq_exit_irqsave(void);
>
> void exit_rcu(void);
>
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -181,7 +181,7 @@ static inline struct tracepoint *tracepo
> */ \
> if (rcuidle) { \
> __idx = srcu_read_lock_notrace(&tracepoint_srcu);\
> - rcu_irq_enter_irqson(); \
> + rcu_irq_enter_irqsave(); \
> } \
> \
> it_func_ptr = rcu_dereference_raw((tp)->funcs); \
> @@ -195,7 +195,7 @@ static inline struct tracepoint *tracepo
> } \
> \
> if (rcuidle) { \
> - rcu_irq_exit_irqson(); \
> + rcu_irq_exit_irqsave(); \
> srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
> } \
> \
> --- a/kernel/cpu_pm.c
> +++ b/kernel/cpu_pm.c
> @@ -24,10 +24,10 @@ static int cpu_pm_notify(enum cpu_pm_eve
> * could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let
> * RCU know this.
> */
> - rcu_irq_enter_irqson();
> + rcu_irq_enter_irqsave();
> ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
> nr_to_call, nr_calls);
> - rcu_irq_exit_irqson();
> + rcu_irq_exit_irqsave();
>
> return notifier_to_errno(ret);
> }
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -699,10 +699,10 @@ void rcu_irq_exit(void)
> /*
> * Wrapper for rcu_irq_exit() where interrupts are enabled.
> *
> - * If you add or remove a call to rcu_irq_exit_irqson(), be sure to test
> + * If you add or remove a call to rcu_irq_exit_irqsave(), be sure to test
> * with CONFIG_RCU_EQS_DEBUG=y.
> */
> -void rcu_irq_exit_irqson(void)
> +void rcu_irq_exit_irqsave(void)
> {
> unsigned long flags;
>
> @@ -875,10 +875,10 @@ void rcu_irq_enter(void)
> /*
> * Wrapper for rcu_irq_enter() where interrupts are enabled.
> *
> - * If you add or remove a call to rcu_irq_enter_irqson(), be sure to test
> + * If you add or remove a call to rcu_irq_enter_irqsave(), be sure to test
> * with CONFIG_RCU_EQS_DEBUG=y.
> */
> -void rcu_irq_enter_irqson(void)
> +void rcu_irq_enter_irqsave(void)
> {
> unsigned long flags;
>
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3004,9 +3004,9 @@ void __trace_stack(struct trace_array *t
> if (unlikely(in_nmi()))
> return;
>
> - rcu_irq_enter_irqson();
> + rcu_irq_enter_irqsave();
> __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
> - rcu_irq_exit_irqson();
> + rcu_irq_exit_irqsave();
> }
>
> /**
>
>