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tracing: Remove definition of trace_*_rcuidle()
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The trace_*_rcuidle() variant of a tracepoint was to handle places where a
tracepoint was located but RCU was not "watching". All those locations
have been removed, and RCU should be watching where all tracepoints are
located. We can now remove the trace_*_rcuidle() variant.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Link: https://lore.kernel.org/20241003181629.36209057@gandalf.local.home
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Steven Rostedt committed Oct 9, 2024
1 parent 4a8840a commit 48bcda6
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Showing 4 changed files with 8 additions and 78 deletions.
50 changes: 2 additions & 48 deletions include/linux/tracepoint.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -196,67 +196,25 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
#define __DO_TRACE_CALL(name, args) __traceiter_##name(NULL, args)
#endif /* CONFIG_HAVE_STATIC_CALL */

/*
* ARCH_WANTS_NO_INSTR archs are expected to have sanitized entry and idle
* code that disallow any/all tracing/instrumentation when RCU isn't watching.
*/
#ifdef CONFIG_ARCH_WANTS_NO_INSTR
#define RCUIDLE_COND(rcuidle) (rcuidle)
#else
/* srcu can't be used from NMI */
#define RCUIDLE_COND(rcuidle) (rcuidle && in_nmi())
#endif

/*
* it_func[0] is never NULL because there is at least one element in the array
* when the array itself is non NULL.
*/
#define __DO_TRACE(name, args, cond, rcuidle) \
#define __DO_TRACE(name, args, cond) \
do { \
int __maybe_unused __idx = 0; \
\
if (!(cond)) \
return; \
\
if (WARN_ONCE(RCUIDLE_COND(rcuidle), \
"Bad RCU usage for tracepoint")) \
return; \
\
/* keep srcu and sched-rcu usage consistent */ \
preempt_disable_notrace(); \
\
/* \
* For rcuidle callers, use srcu since sched-rcu \
* doesn't work from the idle path. \
*/ \
if (rcuidle) { \
__idx = srcu_read_lock_notrace(&tracepoint_srcu);\
ct_irq_enter_irqson(); \
} \
\
__DO_TRACE_CALL(name, TP_ARGS(args)); \
\
if (rcuidle) { \
ct_irq_exit_irqson(); \
srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
} \
\
preempt_enable_notrace(); \
} while (0)

#ifndef MODULE
#define __DECLARE_TRACE_RCU(name, proto, args, cond) \
static inline void trace_##name##_rcuidle(proto) \
{ \
if (static_branch_unlikely(&__tracepoint_##name.key)) \
__DO_TRACE(name, \
TP_ARGS(args), \
TP_CONDITION(cond), 1); \
}
#else
#define __DECLARE_TRACE_RCU(name, proto, args, cond)
#endif

/*
* Make sure the alignment of the structure in the __tracepoints section will
* not add unwanted padding between the beginning of the section and the
Expand All @@ -277,14 +235,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
if (static_branch_unlikely(&__tracepoint_##name.key)) \
__DO_TRACE(name, \
TP_ARGS(args), \
TP_CONDITION(cond), 0); \
TP_CONDITION(cond)); \
if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \
WARN_ONCE(!rcu_is_watching(), \
"RCU not watching for tracepoint"); \
} \
} \
__DECLARE_TRACE_RCU(name, PARAMS(proto), PARAMS(args), \
PARAMS(cond)) \
static inline int \
register_trace_##name(void (*probe)(data_proto), void *data) \
{ \
Expand Down Expand Up @@ -375,8 +331,6 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
#define __DECLARE_TRACE(name, proto, args, cond, data_proto) \
static inline void trace_##name(proto) \
{ } \
static inline void trace_##name##_rcuidle(proto) \
{ } \
static inline int \
register_trace_##name(void (*probe)(data_proto), \
void *data) \
Expand Down
8 changes: 0 additions & 8 deletions include/trace/events/preemptirq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,6 @@ DEFINE_EVENT(preemptirq_template, irq_enable,
#else
#define trace_irq_enable(...)
#define trace_irq_disable(...)
#define trace_irq_enable_rcuidle(...)
#define trace_irq_disable_rcuidle(...)
#endif

#ifdef CONFIG_TRACE_PREEMPT_TOGGLE
Expand All @@ -58,8 +56,6 @@ DEFINE_EVENT(preemptirq_template, preempt_enable,
#else
#define trace_preempt_enable(...)
#define trace_preempt_disable(...)
#define trace_preempt_enable_rcuidle(...)
#define trace_preempt_disable_rcuidle(...)
#endif

#endif /* _TRACE_PREEMPTIRQ_H */
Expand All @@ -69,10 +65,6 @@ DEFINE_EVENT(preemptirq_template, preempt_enable,
#else /* !CONFIG_PREEMPTIRQ_TRACEPOINTS */
#define trace_irq_enable(...)
#define trace_irq_disable(...)
#define trace_irq_enable_rcuidle(...)
#define trace_irq_disable_rcuidle(...)
#define trace_preempt_enable(...)
#define trace_preempt_disable(...)
#define trace_preempt_enable_rcuidle(...)
#define trace_preempt_disable_rcuidle(...)
#endif
26 changes: 6 additions & 20 deletions kernel/trace/trace_preemptirq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,20 +15,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/preemptirq.h>

/*
* Use regular trace points on architectures that implement noinstr
* tooling: these calls will only happen with RCU enabled, which can
* use a regular tracepoint.
*
* On older architectures, use the rcuidle tracing methods (which
* aren't NMI-safe - so exclude NMI contexts):
*/
#ifdef CONFIG_ARCH_WANTS_NO_INSTR
#define trace(point) trace_##point
#else
#define trace(point) if (!in_nmi()) trace_##point##_rcuidle
#endif

#ifdef CONFIG_TRACE_IRQFLAGS
/* Per-cpu variable to prevent redundant calls when IRQs already off */
static DEFINE_PER_CPU(int, tracing_irq_cpu);
Expand All @@ -42,7 +28,7 @@ static DEFINE_PER_CPU(int, tracing_irq_cpu);
void trace_hardirqs_on_prepare(void)
{
if (this_cpu_read(tracing_irq_cpu)) {
trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1);
trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
this_cpu_write(tracing_irq_cpu, 0);
}
Expand All @@ -53,7 +39,7 @@ NOKPROBE_SYMBOL(trace_hardirqs_on_prepare);
void trace_hardirqs_on(void)
{
if (this_cpu_read(tracing_irq_cpu)) {
trace(irq_enable)(CALLER_ADDR0, CALLER_ADDR1);
trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1);
tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1);
this_cpu_write(tracing_irq_cpu, 0);
}
Expand All @@ -75,7 +61,7 @@ void trace_hardirqs_off_finish(void)
if (!this_cpu_read(tracing_irq_cpu)) {
this_cpu_write(tracing_irq_cpu, 1);
tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1);
trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
}

}
Expand All @@ -89,7 +75,7 @@ void trace_hardirqs_off(void)
if (!this_cpu_read(tracing_irq_cpu)) {
this_cpu_write(tracing_irq_cpu, 1);
tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1);
trace(irq_disable)(CALLER_ADDR0, CALLER_ADDR1);
trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1);
}
}
EXPORT_SYMBOL(trace_hardirqs_off);
Expand All @@ -100,13 +86,13 @@ NOKPROBE_SYMBOL(trace_hardirqs_off);

void trace_preempt_on(unsigned long a0, unsigned long a1)
{
trace(preempt_enable)(a0, a1);
trace_preempt_enable(a0, a1);
tracer_preempt_on(a0, a1);
}

void trace_preempt_off(unsigned long a0, unsigned long a1)
{
trace(preempt_disable)(a0, a1);
trace_preempt_disable(a0, a1);
tracer_preempt_off(a0, a1);
}
#endif
2 changes: 0 additions & 2 deletions scripts/tags.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -152,9 +152,7 @@ regex_c=(
'/^BPF_CALL_[0-9]([[:space:]]*\([[:alnum:]_]*\).*/\1/'
'/^COMPAT_SYSCALL_DEFINE[0-9]([[:space:]]*\([[:alnum:]_]*\).*/compat_sys_\1/'
'/^TRACE_EVENT([[:space:]]*\([[:alnum:]_]*\).*/trace_\1/'
'/^TRACE_EVENT([[:space:]]*\([[:alnum:]_]*\).*/trace_\1_rcuidle/'
'/^DEFINE_EVENT([^,)]*,[[:space:]]*\([[:alnum:]_]*\).*/trace_\1/'
'/^DEFINE_EVENT([^,)]*,[[:space:]]*\([[:alnum:]_]*\).*/trace_\1_rcuidle/'
'/^DEFINE_INSN_CACHE_OPS([[:space:]]*\([[:alnum:]_]*\).*/get_\1_slot/'
'/^DEFINE_INSN_CACHE_OPS([[:space:]]*\([[:alnum:]_]*\).*/free_\1_slot/'
'/^PAGEFLAG([[:space:]]*\([[:alnum:]_]*\).*/Page\1/'
Expand Down

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