267 lines
7.8 KiB
C
267 lines
7.8 KiB
C
#ifndef _LINUX_TRACEPOINT_H
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#define _LINUX_TRACEPOINT_H
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/*
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* Kernel Tracepoint API.
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*
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* See Documentation/tracepoint.txt.
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*
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* (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
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*
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* Heavily inspired from the Linux Kernel Markers.
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*
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* This file is released under the GPLv2.
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* See the file COPYING for more details.
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*/
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#include <linux/types.h>
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#include <linux/rcupdate.h>
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struct module;
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struct tracepoint;
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struct tracepoint {
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const char *name; /* Tracepoint name */
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int state; /* State. */
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void **funcs;
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} __attribute__((aligned(32))); /*
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* Aligned on 32 bytes because it is
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* globally visible and gcc happily
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* align these on the structure size.
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* Keep in sync with vmlinux.lds.h.
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*/
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#define TP_PROTO(args...) args
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#define TP_ARGS(args...) args
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#ifdef CONFIG_TRACEPOINTS
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/*
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* it_func[0] is never NULL because there is at least one element in the array
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* when the array itself is non NULL.
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*/
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#define __DO_TRACE(tp, proto, args) \
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do { \
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void **it_func; \
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\
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rcu_read_lock_sched_notrace(); \
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it_func = rcu_dereference((tp)->funcs); \
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if (it_func) { \
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do { \
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((void(*)(proto))(*it_func))(args); \
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} while (*(++it_func)); \
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} \
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rcu_read_unlock_sched_notrace(); \
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} while (0)
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/*
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* Make sure the alignment of the structure in the __tracepoints section will
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* not add unwanted padding between the beginning of the section and the
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* structure. Force alignment to the same alignment as the section start.
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*/
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#define DECLARE_TRACE(name, proto, args) \
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extern struct tracepoint __tracepoint_##name; \
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static inline void trace_##name(proto) \
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{ \
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if (unlikely(__tracepoint_##name.state)) \
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__DO_TRACE(&__tracepoint_##name, \
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TP_PROTO(proto), TP_ARGS(args)); \
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} \
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static inline int register_trace_##name(void (*probe)(proto)) \
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{ \
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return tracepoint_probe_register(#name, (void *)probe); \
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} \
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static inline int unregister_trace_##name(void (*probe)(proto)) \
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{ \
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return tracepoint_probe_unregister(#name, (void *)probe);\
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}
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#define DEFINE_TRACE(name) \
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static const char __tpstrtab_##name[] \
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__attribute__((section("__tracepoints_strings"))) = #name; \
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struct tracepoint __tracepoint_##name \
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__attribute__((section("__tracepoints"), aligned(32))) = \
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{ __tpstrtab_##name, 0, NULL }
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#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
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EXPORT_SYMBOL_GPL(__tracepoint_##name)
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#define EXPORT_TRACEPOINT_SYMBOL(name) \
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EXPORT_SYMBOL(__tracepoint_##name)
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extern void tracepoint_update_probe_range(struct tracepoint *begin,
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struct tracepoint *end);
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#else /* !CONFIG_TRACEPOINTS */
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#define DECLARE_TRACE(name, proto, args) \
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static inline void _do_trace_##name(struct tracepoint *tp, proto) \
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{ } \
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static inline void trace_##name(proto) \
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{ } \
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static inline int register_trace_##name(void (*probe)(proto)) \
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{ \
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return -ENOSYS; \
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} \
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static inline int unregister_trace_##name(void (*probe)(proto)) \
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{ \
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return -ENOSYS; \
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}
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#define DEFINE_TRACE(name)
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#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
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#define EXPORT_TRACEPOINT_SYMBOL(name)
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static inline void tracepoint_update_probe_range(struct tracepoint *begin,
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struct tracepoint *end)
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{ }
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#endif /* CONFIG_TRACEPOINTS */
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/*
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* Connect a probe to a tracepoint.
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* Internal API, should not be used directly.
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*/
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extern int tracepoint_probe_register(const char *name, void *probe);
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/*
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* Disconnect a probe from a tracepoint.
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* Internal API, should not be used directly.
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*/
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extern int tracepoint_probe_unregister(const char *name, void *probe);
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extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
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extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
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extern void tracepoint_probe_update_all(void);
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struct tracepoint_iter {
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struct module *module;
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struct tracepoint *tracepoint;
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};
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extern void tracepoint_iter_start(struct tracepoint_iter *iter);
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extern void tracepoint_iter_next(struct tracepoint_iter *iter);
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extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
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extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
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extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
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struct tracepoint *begin, struct tracepoint *end);
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/*
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* tracepoint_synchronize_unregister must be called between the last tracepoint
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* probe unregistration and the end of module exit to make sure there is no
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* caller executing a probe when it is freed.
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*/
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static inline void tracepoint_synchronize_unregister(void)
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{
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synchronize_sched();
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}
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#define PARAMS(args...) args
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#define TRACE_FORMAT(name, proto, args, fmt) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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/*
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* For use with the TRACE_EVENT macro:
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*
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* We define a tracepoint, its arguments, its printk format
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* and its 'fast binay record' layout.
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*
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* Firstly, name your tracepoint via TRACE_EVENT(name : the
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* 'subsystem_event' notation is fine.
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*
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* Think about this whole construct as the
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* 'trace_sched_switch() function' from now on.
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*
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*
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* TRACE_EVENT(sched_switch,
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*
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* *
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* * A function has a regular function arguments
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* * prototype, declare it via TP_PROTO():
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* *
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*
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* TP_PROTO(struct rq *rq, struct task_struct *prev,
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* struct task_struct *next),
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*
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* *
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* * Define the call signature of the 'function'.
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* * (Design sidenote: we use this instead of a
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* * TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
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* *
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*
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* TP_ARGS(rq, prev, next),
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*
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* *
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* * Fast binary tracing: define the trace record via
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* * TP_STRUCT__entry(). You can think about it like a
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* * regular C structure local variable definition.
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* *
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* * This is how the trace record is structured and will
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* * be saved into the ring buffer. These are the fields
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* * that will be exposed to user-space in
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* * /debug/tracing/events/<*>/format.
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* *
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* * The declared 'local variable' is called '__entry'
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* *
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* * __field(pid_t, prev_prid) is equivalent to a standard declariton:
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* *
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* * pid_t prev_pid;
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* *
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* * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
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* *
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* * char prev_comm[TASK_COMM_LEN];
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* *
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*
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* TP_STRUCT__entry(
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* __array( char, prev_comm, TASK_COMM_LEN )
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* __field( pid_t, prev_pid )
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* __field( int, prev_prio )
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* __array( char, next_comm, TASK_COMM_LEN )
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* __field( pid_t, next_pid )
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* __field( int, next_prio )
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* ),
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*
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* *
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* * Assign the entry into the trace record, by embedding
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* * a full C statement block into TP_fast_assign(). You
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* * can refer to the trace record as '__entry' -
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* * otherwise you can put arbitrary C code in here.
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* *
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* * Note: this C code will execute every time a trace event
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* * happens, on an active tracepoint.
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* *
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*
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* TP_fast_assign(
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* memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
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* __entry->prev_pid = prev->pid;
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* __entry->prev_prio = prev->prio;
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* memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
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* __entry->next_pid = next->pid;
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* __entry->next_prio = next->prio;
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* )
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*
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* *
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* * Formatted output of a trace record via TP_printk().
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* * This is how the tracepoint will appear under ftrace
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* * plugins that make use of this tracepoint.
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* *
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* * (raw-binary tracing wont actually perform this step.)
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* *
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*
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* TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
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* __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
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* __entry->next_comm, __entry->next_pid, __entry->next_prio),
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*
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* );
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*
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* This macro construct is thus used for the regular printk format
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* tracing setup, it is used to construct a function pointer based
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* tracepoint callback (this is used by programmatic plugins and
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* can also by used by generic instrumentation like SystemTap), and
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* it is also used to expose a structured trace record in
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* /debug/tracing/events/.
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*/
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#define TRACE_EVENT(name, proto, args, struct, assign, print) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#endif
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