tracing: pass around ring buffer instead of tracer
The latency tracers (irqsoff and wakeup) can swap trace buffers
on the fly. If an event is happening and has reserved data on one of
the buffers, and the latency tracer swaps the global buffer with the
max buffer, the result is that the event may commit the data to the
wrong buffer.
This patch changes the API to the trace recording to be recieve the
buffer that was used to reserve a commit. Then this buffer can be passed
in to the commit.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 4f5fae6..8712ce3 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -223,6 +223,7 @@
struct syscall_trace_enter *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
int size;
int syscall_nr;
@@ -238,8 +239,8 @@
size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
- event = trace_current_buffer_lock_reserve(sys_data->enter_id, size,
- 0, 0);
+ event = trace_current_buffer_lock_reserve(&buffer, sys_data->enter_id,
+ size, 0, 0);
if (!event)
return;
@@ -247,8 +248,9 @@
entry->nr = syscall_nr;
syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
- if (!filter_current_check_discard(sys_data->enter_event, entry, event))
- trace_current_buffer_unlock_commit(event, 0, 0);
+ if (!filter_current_check_discard(buffer, sys_data->enter_event,
+ entry, event))
+ trace_current_buffer_unlock_commit(buffer, event, 0, 0);
}
void ftrace_syscall_exit(struct pt_regs *regs, long ret)
@@ -256,6 +258,7 @@
struct syscall_trace_exit *entry;
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
int syscall_nr;
syscall_nr = syscall_get_nr(current, regs);
@@ -268,7 +271,7 @@
if (!sys_data)
return;
- event = trace_current_buffer_lock_reserve(sys_data->exit_id,
+ event = trace_current_buffer_lock_reserve(&buffer, sys_data->exit_id,
sizeof(*entry), 0, 0);
if (!event)
return;
@@ -277,8 +280,9 @@
entry->nr = syscall_nr;
entry->ret = syscall_get_return_value(current, regs);
- if (!filter_current_check_discard(sys_data->exit_event, entry, event))
- trace_current_buffer_unlock_commit(event, 0, 0);
+ if (!filter_current_check_discard(buffer, sys_data->exit_event,
+ entry, event))
+ trace_current_buffer_unlock_commit(buffer, event, 0, 0);
}
int reg_event_syscall_enter(void *ptr)