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Message-Id: <6e72b566e85d8df8042f133efbc6c30e21fb017e.1382620672.git.tom.zanussi@linux.intel.com>
Date: Thu, 24 Oct 2013 08:34:19 -0500
From: Tom Zanussi <tom.zanussi@...ux.intel.com>
To: rostedt@...dmis.org
Cc: masami.hiramatsu.pt@...achi.com, linux-kernel@...r.kernel.org,
Tom Zanussi <tom.zanussi@...ux.intel.com>
Subject: [PATCH 3/3] tracing: Add support for SOFT_DISABLE to syscall events
The original SOFT_DISABLE patches didn't add support for soft disable
of syscall events; this adds it.
Add an array of ftrace_event_file pointers indexed by syscall number
to the trace array and remove the existing enabled bitmaps, which as a
result are now redundant. The ftrace_event_file structs in turn
contain the soft disable flags we need for per-syscall soft disable
accounting.
Adding ftrace_event_files also means we can remove the USE_CALL_FILTER
bit, thus enabling multibuffer filter support for syscall events.
Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
---
include/linux/syscalls.h | 4 ++--
kernel/trace/trace.h | 4 ++--
kernel/trace/trace_syscalls.c | 42 ++++++++++++++++++++++++++++++++----------
3 files changed, 36 insertions(+), 14 deletions(-)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 10bafa9..2ef31bf 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -120,7 +120,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
.class = &event_class_syscall_enter, \
.event.funcs = &enter_syscall_print_funcs, \
.data = (void *)&__syscall_meta_##sname,\
- .flags = TRACE_EVENT_FL_CAP_ANY | TRACE_EVENT_FL_USE_CALL_FILTER,\
+ .flags = TRACE_EVENT_FL_CAP_ANY, \
}; \
static struct ftrace_event_call __used \
__attribute__((section("_ftrace_events"))) \
@@ -134,7 +134,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
.class = &event_class_syscall_exit, \
.event.funcs = &exit_syscall_print_funcs, \
.data = (void *)&__syscall_meta_##sname,\
- .flags = TRACE_EVENT_FL_CAP_ANY | TRACE_EVENT_FL_USE_CALL_FILTER,\
+ .flags = TRACE_EVENT_FL_CAP_ANY, \
}; \
static struct ftrace_event_call __used \
__attribute__((section("_ftrace_events"))) \
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 12d1a61..9c27cda 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -192,8 +192,8 @@ struct trace_array {
#ifdef CONFIG_FTRACE_SYSCALLS
int sys_refcount_enter;
int sys_refcount_exit;
- DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
- DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
+ struct ftrace_event_file *enter_syscall_files[NR_syscalls];
+ struct ftrace_event_file *exit_syscall_files[NR_syscalls];
#endif
int stop_count;
int clock_id;
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 32644ee..e4b6d11 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -302,6 +302,7 @@ static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
{
struct trace_array *tr = data;
+ struct ftrace_event_file *ftrace_file;
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
@@ -314,7 +315,13 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
- if (!test_bit(syscall_nr, tr->enabled_enter_syscalls))
+
+ /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
+ ftrace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
+ if (!ftrace_file)
+ return;
+
+ if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
@@ -336,8 +343,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
entry->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
- if (!call_filter_check_discard(sys_data->enter_event, entry,
- buffer, event))
+ if (!filter_check_discard(ftrace_file, entry, buffer, event))
trace_current_buffer_unlock_commit(buffer, event,
irq_flags, pc);
}
@@ -345,6 +351,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
{
struct trace_array *tr = data;
+ struct ftrace_event_file *ftrace_file;
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
@@ -356,7 +363,13 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
syscall_nr = trace_get_syscall_nr(current, regs);
if (syscall_nr < 0)
return;
- if (!test_bit(syscall_nr, tr->enabled_exit_syscalls))
+
+ /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
+ ftrace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
+ if (!ftrace_file)
+ return;
+
+ if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
return;
sys_data = syscall_nr_to_meta(syscall_nr);
@@ -377,8 +390,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);
- if (!call_filter_check_discard(sys_data->exit_event, entry,
- buffer, event))
+ if (!filter_check_discard(ftrace_file, entry, buffer, event))
trace_current_buffer_unlock_commit(buffer, event,
irq_flags, pc);
}
@@ -397,7 +409,7 @@ static int reg_event_syscall_enter(struct ftrace_event_file *file,
if (!tr->sys_refcount_enter)
ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
if (!ret) {
- set_bit(num, tr->enabled_enter_syscalls);
+ rcu_assign_pointer(tr->enter_syscall_files[num], file);
tr->sys_refcount_enter++;
}
mutex_unlock(&syscall_trace_lock);
@@ -415,10 +427,15 @@ static void unreg_event_syscall_enter(struct ftrace_event_file *file,
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_enter--;
- clear_bit(num, tr->enabled_enter_syscalls);
+ rcu_assign_pointer(tr->enter_syscall_files[num], NULL);
if (!tr->sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, tr);
mutex_unlock(&syscall_trace_lock);
+ /*
+ * Callers expect the event to be completely disabled on
+ * return, so wait for current handlers to finish.
+ */
+ synchronize_sched();
}
static int reg_event_syscall_exit(struct ftrace_event_file *file,
@@ -435,7 +452,7 @@ static int reg_event_syscall_exit(struct ftrace_event_file *file,
if (!tr->sys_refcount_exit)
ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
if (!ret) {
- set_bit(num, tr->enabled_exit_syscalls);
+ rcu_assign_pointer(tr->exit_syscall_files[num], file);
tr->sys_refcount_exit++;
}
mutex_unlock(&syscall_trace_lock);
@@ -453,10 +470,15 @@ static void unreg_event_syscall_exit(struct ftrace_event_file *file,
return;
mutex_lock(&syscall_trace_lock);
tr->sys_refcount_exit--;
- clear_bit(num, tr->enabled_exit_syscalls);
+ rcu_assign_pointer(tr->exit_syscall_files[num], NULL);
if (!tr->sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, tr);
mutex_unlock(&syscall_trace_lock);
+ /*
+ * Callers expect the event to be completely disabled on
+ * return, so wait for current handlers to finish.
+ */
+ synchronize_sched();
}
static int __init init_syscall_trace(struct ftrace_event_call *call)
--
1.8.3.1
--
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