Messages in this thread Patch in this message | | | Date | Fri, 10 Dec 2021 16:13:43 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 2/6] sched/preempt: refactor sched_dynamic_update() |
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On Tue, Nov 09, 2021 at 05:24:04PM +0000, Mark Rutland wrote: > Currently sched_dynamic_update needs to open-code the enabled/disabled > function names for each preemption model it supoprts, when in practice > this is a boolean enabled/disabled state for each function. > > Make this clearer and avoid repetition by defining the enabled/disabled > states at the function definition, and using helper macros to peform the > static_call_update(). Where x86 currently overrides the enabled > function, it is made to provide both the enabled and disabled states for > consistency, with defaults provided by the core code otherwise. > > In subsequent patches this will allow us to support PREEMPT_DYNAMIC > without static calls. > > There shoud be no functional change as a result of this patch. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Ard Biesheuvel <ardb@kernel.org> > Cc: Frederic Weisbecker <frederic@kernel.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Juri Lelli <juri.lelli@redhat.com> > Cc: Peter Zijlstra <peterz@infradead.org> > --- > arch/x86/include/asm/preempt.h | 10 ++++--- > include/linux/entry-common.h | 2 ++ > kernel/sched/core.c | 59 ++++++++++++++++++++++++++---------------- > 3 files changed, 45 insertions(+), 26 deletions(-) > > diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h > index fe5efbcba824..5f6daea1ee24 100644 > --- a/arch/x86/include/asm/preempt.h > +++ b/arch/x86/include/asm/preempt.h > @@ -108,16 +108,18 @@ static __always_inline bool should_resched(int preempt_offset) > extern asmlinkage void preempt_schedule(void); > extern asmlinkage void preempt_schedule_thunk(void); > > -#define __preempt_schedule_func preempt_schedule_thunk > +#define preempt_schedule_dynamic_enabled preempt_schedule_thunk > +#define preempt_schedule_dynamic_disabled NULL > > extern asmlinkage void preempt_schedule_notrace(void); > extern asmlinkage void preempt_schedule_notrace_thunk(void); > > -#define __preempt_schedule_notrace_func preempt_schedule_notrace_thunk > +#define preempt_schedule_notrace_dynamic_enabled preempt_schedule_notrace_thunk > +#define preempt_schedule_notrace_dynamic_disabled NULL
I'm worried about un-greppable macro definitions like this. Also this enable/disable switch look like a common pattern on static call so how about moving that logic to static call itself? As in below (only build-tested):
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index fe5efbcba824..64320c0a00a6 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -117,7 +117,7 @@ extern asmlinkage void preempt_schedule_notrace_thunk(void); #ifdef CONFIG_PREEMPT_DYNAMIC -DECLARE_STATIC_CALL(preempt_schedule, __preempt_schedule_func); +DECLARE_STATIC_CALL_TOGGLE(preempt_schedule, __preempt_schedule_func); #define __preempt_schedule() \ do { \ @@ -125,7 +125,7 @@ do { \ asm volatile ("call " STATIC_CALL_TRAMP_STR(preempt_schedule) : ASM_CALL_CONSTRAINT); \ } while (0) -DECLARE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func); +DECLARE_STATIC_CALL_TOGGLE(preempt_schedule_notrace, __preempt_schedule_notrace_func); #define __preempt_schedule_notrace() \ do { \ diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 2e2b8d6140ed..a3d99ffc32ca 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -456,7 +456,7 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs); */ void irqentry_exit_cond_resched(void); #ifdef CONFIG_PREEMPT_DYNAMIC -DECLARE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched); +DECLARE_STATIC_CALL_TOGGLE(irqentry_exit_cond_resched, irqentry_exit_cond_resched); #endif /** diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 77755ac3e189..f4f5f4f3b496 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -94,7 +94,7 @@ extern int __cond_resched(void); extern int __cond_resched(void); -DECLARE_STATIC_CALL(might_resched, __cond_resched); +DECLARE_STATIC_CALL_TOGGLE(might_resched, __cond_resched); static __always_inline void might_resched(void) { diff --git a/include/linux/sched.h b/include/linux/sched.h index 78c351e35fec..01a9e8590ea0 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2010,7 +2010,7 @@ extern int __cond_resched(void); #ifdef CONFIG_PREEMPT_DYNAMIC -DECLARE_STATIC_CALL(cond_resched, __cond_resched); +DECLARE_STATIC_CALL_TOGGLE(cond_resched, __cond_resched); static __always_inline int _cond_resched(void) { diff --git a/include/linux/static_call.h b/include/linux/static_call.h index 3e56a9751c06..351ac27fa9d1 100644 --- a/include/linux/static_call.h +++ b/include/linux/static_call.h @@ -156,6 +156,19 @@ extern void arch_static_call_transform(void *site, void *tramp, void *func, bool STATIC_CALL_TRAMP_ADDR(name), __F); \ }) +#define static_call_toggle(name, enable) \ +({ \ + struct static_call_toggle *__G = &STATIC_CALL_TOGGLE(name); \ + if (enable) \ + static_call_update(name, __G->func_enabled); \ + else \ + static_call_update(name, __G->func_disabled); \ +}) + +#define static_call_enable(name) static_call_toggle(name, 1); +#define static_call_disable(name) static_call_toggle(name, 0); + + #define static_call_query(name) (READ_ONCE(STATIC_CALL_KEY(name).func)) #ifdef CONFIG_HAVE_STATIC_CALL_INLINE @@ -333,4 +346,27 @@ static inline int static_call_text_reserved(void *start, void *end) #define DEFINE_STATIC_CALL_RET0(name, _func) \ __DEFINE_STATIC_CALL(name, _func, __static_call_return0) +#define __DEFINE_STATIC_CALL_TOGGLE(name, _func_enabled, _func_disabled) \ + struct static_call_toggle STATIC_CALL_TOGGLE(name) = { \ + .key = &STATIC_CALL_KEY(name), \ + .func_enabled = _func_enabled, \ + .func_disabled = _func_disabled, \ + } + +#define DEFINE_STATIC_CALL_ENABLED(name, _func) \ + DEFINE_STATIC_CALL(name, _func); \ + __DEFINE_STATIC_CALL_TOGGLE(name, _func, NULL) + +#define DEFINE_STATIC_CALL_DISABLED(name, _func) \ + DEFINE_STATIC_CALL_NULL(name, _func); \ + __DEFINE_STATIC_CALL_TOGGLE(name, _func, NULL) + +#define DEFINE_STATIC_CALL_ENABLED_RET0(name, _func) \ + DEFINE_STATIC_CALL(name, _func); \ + __DEFINE_STATIC_CALL_TOGGLE(name, _func, __static_call_return0) + +#define DEFINE_STATIC_CALL_DISABLED_RET0(name, _func) \ + DEFINE_STATIC_CALL_RET0(name, _func); \ + __DEFINE_STATIC_CALL_TOGGLE(name, _func, __static_call_return0) + #endif /* _LINUX_STATIC_CALL_H */ diff --git a/include/linux/static_call_types.h b/include/linux/static_call_types.h index 5a00b8b2cf9f..e150f29aee2d 100644 --- a/include/linux/static_call_types.h +++ b/include/linux/static_call_types.h @@ -18,6 +18,9 @@ #define STATIC_CALL_TRAMP(name) __PASTE(STATIC_CALL_TRAMP_PREFIX, name) #define STATIC_CALL_TRAMP_STR(name) __stringify(STATIC_CALL_TRAMP(name)) +#define STATIC_CALL_TOGGLE_PREFIX __SCG_ +#define STATIC_CALL_TOGGLE(name) __PASTE(STATIC_CALL_TOGGLE_PREFIX, name) + /* * Flags in the low bits of static_call_site::key. */ @@ -38,6 +41,10 @@ struct static_call_site { extern struct static_call_key STATIC_CALL_KEY(name); \ extern typeof(func) STATIC_CALL_TRAMP(name); +#define DECLARE_STATIC_CALL_TOGGLE(name, func) \ + DECLARE_STATIC_CALL(name, func); \ + extern struct static_call_toggle STATIC_CALL_TOGGLE(name); + #ifdef CONFIG_HAVE_STATIC_CALL #define __raw_static_call(name) (&STATIC_CALL_TRAMP(name)) @@ -68,6 +75,13 @@ struct static_call_key { }; }; +struct static_call_toggle { + struct static_call_key *key; + void *func_enabled; + void *func_disabled; +}; + + #else /* !CONFIG_HAVE_STATIC_CALL_INLINE */ #define __STATIC_CALL_ADDRESSABLE(name) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index d5a61d565ad5..d48b91579475 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -392,7 +392,7 @@ void irqentry_exit_cond_resched(void) } } #ifdef CONFIG_PREEMPT_DYNAMIC -DEFINE_STATIC_CALL(irqentry_exit_cond_resched, irqentry_exit_cond_resched); +DEFINE_STATIC_CALL_ENABLED(irqentry_exit_cond_resched, irqentry_exit_cond_resched); #endif noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 27c795fbcaaf..389fcc412e6b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6447,7 +6447,7 @@ NOKPROBE_SYMBOL(preempt_schedule); EXPORT_SYMBOL(preempt_schedule); #ifdef CONFIG_PREEMPT_DYNAMIC -DEFINE_STATIC_CALL(preempt_schedule, __preempt_schedule_func); +DEFINE_STATIC_CALL_ENABLED(preempt_schedule, __preempt_schedule_func); EXPORT_STATIC_CALL_TRAMP(preempt_schedule); #endif @@ -6505,7 +6505,7 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) EXPORT_SYMBOL_GPL(preempt_schedule_notrace); #ifdef CONFIG_PREEMPT_DYNAMIC -DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func); +DEFINE_STATIC_CALL_ENABLED(preempt_schedule_notrace, __preempt_schedule_notrace_func); EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace); #endif @@ -8016,10 +8016,9 @@ EXPORT_SYMBOL(__cond_resched); #endif #ifdef CONFIG_PREEMPT_DYNAMIC -DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched); +DEFINE_STATIC_CALL_DISABLED_RET0(cond_resched, __cond_resched); EXPORT_STATIC_CALL_TRAMP(cond_resched); - -DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched); +DEFINE_STATIC_CALL_DISABLED_RET0(might_resched, __cond_resched); EXPORT_STATIC_CALL_TRAMP(might_resched); #endif @@ -8154,37 +8153,37 @@ void sched_dynamic_update(int mode) * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in * the ZERO state, which is invalid. */ - static_call_update(cond_resched, __cond_resched); - static_call_update(might_resched, __cond_resched); - static_call_update(preempt_schedule, __preempt_schedule_func); - static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); - static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); + static_call_enable(cond_resched); + static_call_enable(might_resched); + static_call_enable(preempt_schedule); + static_call_enable(preempt_schedule_notrace); + static_call_enable(irqentry_exit_cond_resched); switch (mode) { case preempt_dynamic_none: - static_call_update(cond_resched, __cond_resched); - static_call_update(might_resched, (void *)&__static_call_return0); - static_call_update(preempt_schedule, NULL); - static_call_update(preempt_schedule_notrace, NULL); - static_call_update(irqentry_exit_cond_resched, NULL); + static_call_enable(cond_resched); + static_call_disable(might_resched); + static_call_disable(preempt_schedule); + static_call_disable(preempt_schedule_notrace); + static_call_disable(irqentry_exit_cond_resched); pr_info("Dynamic Preempt: none\n"); break; case preempt_dynamic_voluntary: - static_call_update(cond_resched, __cond_resched); - static_call_update(might_resched, __cond_resched); - static_call_update(preempt_schedule, NULL); - static_call_update(preempt_schedule_notrace, NULL); - static_call_update(irqentry_exit_cond_resched, NULL); + static_call_enable(cond_resched); + static_call_enable(might_resched); + static_call_disable(preempt_schedule); + static_call_disable(preempt_schedule_notrace); + static_call_disable(irqentry_exit_cond_resched); pr_info("Dynamic Preempt: voluntary\n"); break; case preempt_dynamic_full: - static_call_update(cond_resched, (void *)&__static_call_return0); - static_call_update(might_resched, (void *)&__static_call_return0); - static_call_update(preempt_schedule, __preempt_schedule_func); - static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); - static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); + static_call_disable(cond_resched); + static_call_disable(might_resched); + static_call_enable(preempt_schedule); + static_call_enable(preempt_schedule_notrace); + static_call_enable(irqentry_exit_cond_resched); pr_info("Dynamic Preempt: full\n"); break; }
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