b118415bfa
When we want to filter an event, the filter test is done after the event is commited to the ring-buffer to be discarded later if needed. But a reader could be reading this event while we are trying to discard it. Other kind of racy events can even happen because the event is commited and can be read and/or consumed. What we want is to discard the event before committing it. Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Tom Zanussi <tzanussi@gmail.com> LKML-Reference: <1237763919-21505-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
282 lines
7.5 KiB
C
282 lines
7.5 KiB
C
/*
|
|
* Stage 3 of the trace events.
|
|
*
|
|
* Override the macros in <trace/trace_event_types.h> to include the following:
|
|
*
|
|
* static void ftrace_event_<call>(proto)
|
|
* {
|
|
* event_trace_printk(_RET_IP_, "<call>: " <fmt>);
|
|
* }
|
|
*
|
|
* static int ftrace_reg_event_<call>(void)
|
|
* {
|
|
* int ret;
|
|
*
|
|
* ret = register_trace_<call>(ftrace_event_<call>);
|
|
* if (!ret)
|
|
* pr_info("event trace: Could not activate trace point "
|
|
* "probe to <call>");
|
|
* return ret;
|
|
* }
|
|
*
|
|
* static void ftrace_unreg_event_<call>(void)
|
|
* {
|
|
* unregister_trace_<call>(ftrace_event_<call>);
|
|
* }
|
|
*
|
|
* For those macros defined with TRACE_FORMAT:
|
|
*
|
|
* static struct ftrace_event_call __used
|
|
* __attribute__((__aligned__(4)))
|
|
* __attribute__((section("_ftrace_events"))) event_<call> = {
|
|
* .name = "<call>",
|
|
* .regfunc = ftrace_reg_event_<call>,
|
|
* .unregfunc = ftrace_unreg_event_<call>,
|
|
* }
|
|
*
|
|
*
|
|
* For those macros defined with TRACE_EVENT:
|
|
*
|
|
* static struct ftrace_event_call event_<call>;
|
|
*
|
|
* static void ftrace_raw_event_<call>(proto)
|
|
* {
|
|
* struct ring_buffer_event *event;
|
|
* struct ftrace_raw_<call> *entry; <-- defined in stage 1
|
|
* unsigned long irq_flags;
|
|
* int pc;
|
|
*
|
|
* local_save_flags(irq_flags);
|
|
* pc = preempt_count();
|
|
*
|
|
* event = trace_current_buffer_lock_reserve(event_<call>.id,
|
|
* sizeof(struct ftrace_raw_<call>),
|
|
* irq_flags, pc);
|
|
* if (!event)
|
|
* return;
|
|
* entry = ring_buffer_event_data(event);
|
|
*
|
|
* <assign>; <-- Here we assign the entries by the __field and
|
|
* __array macros.
|
|
*
|
|
* trace_current_buffer_unlock_commit(event, irq_flags, pc);
|
|
* }
|
|
*
|
|
* static int ftrace_raw_reg_event_<call>(void)
|
|
* {
|
|
* int ret;
|
|
*
|
|
* ret = register_trace_<call>(ftrace_raw_event_<call>);
|
|
* if (!ret)
|
|
* pr_info("event trace: Could not activate trace point "
|
|
* "probe to <call>");
|
|
* return ret;
|
|
* }
|
|
*
|
|
* static void ftrace_unreg_event_<call>(void)
|
|
* {
|
|
* unregister_trace_<call>(ftrace_raw_event_<call>);
|
|
* }
|
|
*
|
|
* static struct trace_event ftrace_event_type_<call> = {
|
|
* .trace = ftrace_raw_output_<call>, <-- stage 2
|
|
* };
|
|
*
|
|
* static int ftrace_raw_init_event_<call>(void)
|
|
* {
|
|
* int id;
|
|
*
|
|
* id = register_ftrace_event(&ftrace_event_type_<call>);
|
|
* if (!id)
|
|
* return -ENODEV;
|
|
* event_<call>.id = id;
|
|
* return 0;
|
|
* }
|
|
*
|
|
* static struct ftrace_event_call __used
|
|
* __attribute__((__aligned__(4)))
|
|
* __attribute__((section("_ftrace_events"))) event_<call> = {
|
|
* .name = "<call>",
|
|
* .system = "<system>",
|
|
* .raw_init = ftrace_raw_init_event_<call>,
|
|
* .regfunc = ftrace_reg_event_<call>,
|
|
* .unregfunc = ftrace_unreg_event_<call>,
|
|
* .show_format = ftrace_format_<call>,
|
|
* }
|
|
*
|
|
*/
|
|
|
|
#undef TP_FMT
|
|
#define TP_FMT(fmt, args...) fmt "\n", ##args
|
|
|
|
#ifdef CONFIG_EVENT_PROFILE
|
|
#define _TRACE_PROFILE(call, proto, args) \
|
|
static void ftrace_profile_##call(proto) \
|
|
{ \
|
|
extern void perf_tpcounter_event(int); \
|
|
perf_tpcounter_event(event_##call.id); \
|
|
} \
|
|
\
|
|
static int ftrace_profile_enable_##call(struct ftrace_event_call *call) \
|
|
{ \
|
|
int ret = 0; \
|
|
\
|
|
if (!atomic_inc_return(&call->profile_count)) \
|
|
ret = register_trace_##call(ftrace_profile_##call); \
|
|
\
|
|
return ret; \
|
|
} \
|
|
\
|
|
static void ftrace_profile_disable_##call(struct ftrace_event_call *call) \
|
|
{ \
|
|
if (atomic_add_negative(-1, &call->profile_count)) \
|
|
unregister_trace_##call(ftrace_profile_##call); \
|
|
}
|
|
|
|
#define _TRACE_PROFILE_INIT(call) \
|
|
.profile_count = ATOMIC_INIT(-1), \
|
|
.profile_enable = ftrace_profile_enable_##call, \
|
|
.profile_disable = ftrace_profile_disable_##call,
|
|
|
|
#else
|
|
#define _TRACE_PROFILE(call, proto, args)
|
|
#define _TRACE_PROFILE_INIT(call)
|
|
#endif
|
|
|
|
#define _TRACE_FORMAT(call, proto, args, fmt) \
|
|
static void ftrace_event_##call(proto) \
|
|
{ \
|
|
event_trace_printk(_RET_IP_, #call ": " fmt); \
|
|
} \
|
|
\
|
|
static int ftrace_reg_event_##call(void) \
|
|
{ \
|
|
int ret; \
|
|
\
|
|
ret = register_trace_##call(ftrace_event_##call); \
|
|
if (ret) \
|
|
pr_info("event trace: Could not activate trace point " \
|
|
"probe to " #call "\n"); \
|
|
return ret; \
|
|
} \
|
|
\
|
|
static void ftrace_unreg_event_##call(void) \
|
|
{ \
|
|
unregister_trace_##call(ftrace_event_##call); \
|
|
} \
|
|
\
|
|
static struct ftrace_event_call event_##call; \
|
|
\
|
|
static int ftrace_init_event_##call(void) \
|
|
{ \
|
|
int id; \
|
|
\
|
|
id = register_ftrace_event(NULL); \
|
|
if (!id) \
|
|
return -ENODEV; \
|
|
event_##call.id = id; \
|
|
return 0; \
|
|
}
|
|
|
|
#undef TRACE_FORMAT
|
|
#define TRACE_FORMAT(call, proto, args, fmt) \
|
|
_TRACE_FORMAT(call, PARAMS(proto), PARAMS(args), PARAMS(fmt)) \
|
|
_TRACE_PROFILE(call, PARAMS(proto), PARAMS(args)) \
|
|
static struct ftrace_event_call __used \
|
|
__attribute__((__aligned__(4))) \
|
|
__attribute__((section("_ftrace_events"))) event_##call = { \
|
|
.name = #call, \
|
|
.system = __stringify(TRACE_SYSTEM), \
|
|
.raw_init = ftrace_init_event_##call, \
|
|
.regfunc = ftrace_reg_event_##call, \
|
|
.unregfunc = ftrace_unreg_event_##call, \
|
|
_TRACE_PROFILE_INIT(call) \
|
|
}
|
|
|
|
#undef __entry
|
|
#define __entry entry
|
|
|
|
#undef TRACE_EVENT
|
|
#define TRACE_EVENT(call, proto, args, tstruct, assign, print) \
|
|
_TRACE_PROFILE(call, PARAMS(proto), PARAMS(args)) \
|
|
\
|
|
static struct ftrace_event_call event_##call; \
|
|
\
|
|
static void ftrace_raw_event_##call(proto) \
|
|
{ \
|
|
struct ftrace_event_call *call = &event_##call; \
|
|
struct ring_buffer_event *event; \
|
|
struct ftrace_raw_##call *entry; \
|
|
unsigned long irq_flags; \
|
|
int pc; \
|
|
\
|
|
local_save_flags(irq_flags); \
|
|
pc = preempt_count(); \
|
|
\
|
|
event = trace_current_buffer_lock_reserve(event_##call.id, \
|
|
sizeof(struct ftrace_raw_##call), \
|
|
irq_flags, pc); \
|
|
if (!event) \
|
|
return; \
|
|
entry = ring_buffer_event_data(event); \
|
|
\
|
|
assign; \
|
|
\
|
|
if (call->preds && !filter_match_preds(call, entry)) \
|
|
ring_buffer_event_discard(event); \
|
|
\
|
|
trace_nowake_buffer_unlock_commit(event, irq_flags, pc); \
|
|
\
|
|
} \
|
|
\
|
|
static int ftrace_raw_reg_event_##call(void) \
|
|
{ \
|
|
int ret; \
|
|
\
|
|
ret = register_trace_##call(ftrace_raw_event_##call); \
|
|
if (ret) \
|
|
pr_info("event trace: Could not activate trace point " \
|
|
"probe to " #call "\n"); \
|
|
return ret; \
|
|
} \
|
|
\
|
|
static void ftrace_raw_unreg_event_##call(void) \
|
|
{ \
|
|
unregister_trace_##call(ftrace_raw_event_##call); \
|
|
} \
|
|
\
|
|
static struct trace_event ftrace_event_type_##call = { \
|
|
.trace = ftrace_raw_output_##call, \
|
|
}; \
|
|
\
|
|
static int ftrace_raw_init_event_##call(void) \
|
|
{ \
|
|
int id; \
|
|
\
|
|
id = register_ftrace_event(&ftrace_event_type_##call); \
|
|
if (!id) \
|
|
return -ENODEV; \
|
|
event_##call.id = id; \
|
|
INIT_LIST_HEAD(&event_##call.fields); \
|
|
return 0; \
|
|
} \
|
|
\
|
|
static struct ftrace_event_call __used \
|
|
__attribute__((__aligned__(4))) \
|
|
__attribute__((section("_ftrace_events"))) event_##call = { \
|
|
.name = #call, \
|
|
.system = __stringify(TRACE_SYSTEM), \
|
|
.raw_init = ftrace_raw_init_event_##call, \
|
|
.regfunc = ftrace_raw_reg_event_##call, \
|
|
.unregfunc = ftrace_raw_unreg_event_##call, \
|
|
.show_format = ftrace_format_##call, \
|
|
.define_fields = ftrace_define_fields_##call, \
|
|
_TRACE_PROFILE_INIT(call) \
|
|
}
|
|
|
|
#include <trace/trace_event_types.h>
|
|
|
|
#undef _TRACE_PROFILE
|
|
#undef _TRACE_PROFILE_INIT
|
|
|