[ltt-dev] [RFC] TRACE_EVENT: mapping "=" and memcpy to macros

[Mathieu Desnoyers]

LTTng needs to override the assignment primitives to deal with cross-page
writes. A first step needed to move LTTng to TRACE_EVENT is to introduce the
following macros:

for ftrace and perf:

#define __assign(dest, src)                  (dest) = (src)
#define __assign_memcpy(dest, src, len)      memcpy(dest, src, len)

which would turn (e.g.)

        TP_fast_assign(
                memcpy(__entry->comm, t->comm, TASK_COMM_LEN);
                __entry->pid    = t->pid;
        ),

into

        TP_fast_assign(
                __assign_memcpy(__entry->comm, t->comm, TASK_COMM_LEN);
                __assign(__entry->pid, t->pid);
        ),

So LTTng (and other tracers) can override these with their own primitives. This
is a basic step required to bring the LTTng tree closer to mainline.

Thoughts ?

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com