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![Mathieu Desnoyers](/assets/img/avatar_default.png)
Copy the information needed from struct module into a local module list held within tracepoint.c from within the module coming/going notifier. This vastly simplifies locking of tracepoint registration / unregistration, because we don't have to take the module mutex to register and unregister tracepoints anymore. Steven Rostedt ran into dependency problems related to modules mutex vs kprobes mutex vs ftrace mutex vs tracepoint mutex that seems to be hard to fix without removing this dependency between tracepoint and module mutex. (note: it should be investigated whether kprobes could benefit of being dissociated from the modules mutex too.) This also fixes module handling of tracepoint list iterators, because it was expecting the list to be sorted by pointer address. Given we have control on our own list now, it's OK to sort this list which has tracepoints as its only purpose. The reason why this sorting is required is to handle the fact that seq files (and any read() operation from user-space) cannot hold the tracepoint mutex across multiple calls, so list entries may vanish between calls. With sorting, the tracepoint iterator becomes usable even if the list don't contain the exact item pointed to by the iterator anymore. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Jason Baron <jbaron@redhat.com> CC: Ingo Molnar <mingo@elte.hu> CC: Lai Jiangshan <laijs@cn.fujitsu.com> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> CC: Thomas Gleixner <tglx@linutronix.de> CC: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Link: http://lkml.kernel.org/r/20110810191839.GC8525@Krystal Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
378 lines
12 KiB
C
378 lines
12 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/trace/tracepoints.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/errno.h>
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#include <linux/types.h>
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#include <linux/rcupdate.h>
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#include <linux/jump_label.h>
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struct module;
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struct tracepoint;
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struct tracepoint_func {
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void *func;
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void *data;
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};
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struct tracepoint {
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const char *name; /* Tracepoint name */
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struct jump_label_key key;
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void (*regfunc)(void);
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void (*unregfunc)(void);
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struct tracepoint_func __rcu *funcs;
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};
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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, void *data);
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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
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tracepoint_probe_unregister(const char *name, void *probe, void *data);
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extern int tracepoint_probe_register_noupdate(const char *name, void *probe,
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void *data);
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extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
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void *data);
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extern void tracepoint_probe_update_all(void);
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#ifdef CONFIG_MODULES
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struct tp_module {
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struct list_head list;
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unsigned int num_tracepoints;
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struct tracepoint * const *tracepoints_ptrs;
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};
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#endif /* CONFIG_MODULES */
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struct tracepoint_iter {
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#ifdef CONFIG_MODULES
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struct tp_module *module;
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#endif /* CONFIG_MODULES */
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struct tracepoint * const *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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/*
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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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#endif /* _LINUX_TRACEPOINT_H */
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/*
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* Note: we keep the TRACE_EVENT and DECLARE_TRACE outside the include
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* file ifdef protection.
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* This is due to the way trace events work. If a file includes two
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* trace event headers under one "CREATE_TRACE_POINTS" the first include
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* will override the TRACE_EVENT and break the second include.
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*/
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#ifndef DECLARE_TRACE
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#define TP_PROTO(args...) args
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#define TP_ARGS(args...) args
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#define TP_CONDITION(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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* Note, the proto and args passed in includes "__data" as the first parameter.
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* The reason for this is to handle the "void" prototype. If a tracepoint
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* has a "void" prototype, then it is invalid to declare a function
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* as "(void *, void)". The DECLARE_TRACE_NOARGS() will pass in just
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* "void *data", where as the DECLARE_TRACE() will pass in "void *data, proto".
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*/
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#define __DO_TRACE(tp, proto, args, cond) \
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do { \
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struct tracepoint_func *it_func_ptr; \
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void *it_func; \
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void *__data; \
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\
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if (!(cond)) \
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return; \
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rcu_read_lock_sched_notrace(); \
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it_func_ptr = rcu_dereference_sched((tp)->funcs); \
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if (it_func_ptr) { \
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do { \
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it_func = (it_func_ptr)->func; \
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__data = (it_func_ptr)->data; \
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((void(*)(proto))(it_func))(args); \
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} while ((++it_func_ptr)->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, cond, data_proto, data_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 (static_branch(&__tracepoint_##name.key)) \
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__DO_TRACE(&__tracepoint_##name, \
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TP_PROTO(data_proto), \
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TP_ARGS(data_args), \
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TP_CONDITION(cond)); \
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} \
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static inline int \
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register_trace_##name(void (*probe)(data_proto), void *data) \
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{ \
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return tracepoint_probe_register(#name, (void *)probe, \
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data); \
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} \
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static inline int \
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unregister_trace_##name(void (*probe)(data_proto), void *data) \
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{ \
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return tracepoint_probe_unregister(#name, (void *)probe, \
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data); \
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} \
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static inline void \
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check_trace_callback_type_##name(void (*cb)(data_proto)) \
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{ \
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}
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/*
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* We have no guarantee that gcc and the linker won't up-align the tracepoint
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* structures, so we create an array of pointers that will be used for iteration
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* on the tracepoints.
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*/
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#define DEFINE_TRACE_FN(name, reg, unreg) \
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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"))) = \
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{ __tpstrtab_##name, JUMP_LABEL_INIT, reg, unreg, NULL };\
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static struct tracepoint * const __tracepoint_ptr_##name __used \
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__attribute__((section("__tracepoints_ptrs"))) = \
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&__tracepoint_##name;
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#define DEFINE_TRACE(name) \
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DEFINE_TRACE_FN(name, NULL, 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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#else /* !CONFIG_TRACEPOINTS */
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#define __DECLARE_TRACE(name, proto, args, cond, data_proto, data_args) \
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static inline void trace_##name(proto) \
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{ } \
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static inline int \
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register_trace_##name(void (*probe)(data_proto), \
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void *data) \
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{ \
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return -ENOSYS; \
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} \
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static inline int \
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unregister_trace_##name(void (*probe)(data_proto), \
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void *data) \
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{ \
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return -ENOSYS; \
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} \
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static inline void check_trace_callback_type_##name(void (*cb)(data_proto)) \
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{ \
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}
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#define DEFINE_TRACE_FN(name, reg, unreg)
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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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#endif /* CONFIG_TRACEPOINTS */
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/*
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* The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
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* (void). "void" is a special value in a function prototype and can
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* not be combined with other arguments. Since the DECLARE_TRACE()
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* macro adds a data element at the beginning of the prototype,
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* we need a way to differentiate "(void *data, proto)" from
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* "(void *data, void)". The second prototype is invalid.
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*
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* DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
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* and "void *__data" as the callback prototype.
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*
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* DECLARE_TRACE() passes "proto" as the tracepoint protoype and
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* "void *__data, proto" as the callback prototype.
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*/
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#define DECLARE_TRACE_NOARGS(name) \
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__DECLARE_TRACE(name, void, , 1, void *__data, __data)
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#define DECLARE_TRACE(name, proto, args) \
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__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), 1, \
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PARAMS(void *__data, proto), \
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PARAMS(__data, args))
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#define DECLARE_TRACE_CONDITION(name, proto, args, cond) \
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__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args), PARAMS(cond), \
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PARAMS(void *__data, proto), \
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PARAMS(__data, args))
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#define TRACE_EVENT_FLAGS(event, flag)
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#endif /* DECLARE_TRACE */
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#ifndef TRACE_EVENT
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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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* * /sys/kernel/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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* /sys/kernel/debug/tracing/events/.
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*
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* A set of (un)registration functions can be passed to the variant
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* TRACE_EVENT_FN to perform any (un)registration work.
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*/
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#define DECLARE_EVENT_CLASS(name, proto, args, tstruct, assign, print)
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#define DEFINE_EVENT(template, name, proto, args) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define DEFINE_EVENT_CONDITION(template, name, proto, \
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args, cond) \
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DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
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PARAMS(args), PARAMS(cond))
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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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#define TRACE_EVENT_FN(name, proto, args, struct, \
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assign, print, reg, unreg) \
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DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))
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#define TRACE_EVENT_CONDITION(name, proto, args, cond, \
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struct, assign, print) \
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DECLARE_TRACE_CONDITION(name, PARAMS(proto), \
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PARAMS(args), PARAMS(cond))
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#define TRACE_EVENT_FLAGS(event, flag)
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#endif /* ifdef TRACE_EVENT (see note above) */
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