From 9327904dcbf2708823c05baa7532783fb0214792 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Fri, 7 Mar 2014 10:41:32 +0100 Subject: Teach the call_time trace to notice when the trace dies (non-SMP system) The call_time trace is a special kind of tracing that requires a tracer process just like ordinary call trace, but it never actually sends anything to the tracer. It merely use the existence of a trace process (and call trace flags) as an indication that call_time tracing is active for the process. If the tracer dies in a non-SMP run-time system, processes with call_time tracing would not notice that the tracer had died. Furthermore, if the set_on_spawn flag was active, the dead tracer could be propagaged to newly spawned processes. Before accumulating trace information in a non-SMP system, always validate the tracer process. (In an SMP system, a reference to a dead tracer will be cleared away each time a process is scheduled.) While we could put all of the new code beam_bp.c, we have chosen to make a function call from beam_bp.c to a function in erl_trace.c for clarity's sake and to ease further maintenance. In the future, we might want to handle tracing in more similar ways in the SMP and non-SMP system. --- erts/emulator/beam/beam_bp.c | 5 +++-- erts/emulator/beam/erl_trace.c | 19 +++++++++++++++++++ erts/emulator/beam/erl_trace.h | 1 + 3 files changed, 23 insertions(+), 2 deletions(-) (limited to 'erts/emulator/beam') diff --git a/erts/emulator/beam/beam_bp.c b/erts/emulator/beam/beam_bp.c index 49a34ab4ad..4e711c89e0 100644 --- a/erts/emulator/beam/beam_bp.c +++ b/erts/emulator/beam/beam_bp.c @@ -642,7 +642,7 @@ erts_generic_breakpoint(Process* c_p, BeamInstr* I, Eterm* reg) erts_smp_atomic_inc_nob(&bp->count->acount); } - if (bp_flags & ERTS_BPF_TIME_TRACE_ACTIVE) { + if (bp_flags & ERTS_BPF_TIME_TRACE_ACTIVE && erts_is_tracer_proc_valid(c_p)) { Eterm w; erts_trace_time_call(c_p, I, bp->time); w = (BeamInstr) *c_p->cp; @@ -730,7 +730,8 @@ erts_bif_trace(int bif_index, Process* p, Eterm* args, BeamInstr* I) } } if (bp_flags & ERTS_BPF_TIME_TRACE_ACTIVE && - IS_TRACED_FL(p, F_TRACE_CALLS)) { + IS_TRACED_FL(p, F_TRACE_CALLS) && + erts_is_tracer_proc_valid(p)) { BeamInstr *pc = (BeamInstr *)ep->code+3; erts_trace_time_call(p, pc, bp->time); } diff --git a/erts/emulator/beam/erl_trace.c b/erts/emulator/beam/erl_trace.c index 6978a5f11a..305058ceff 100644 --- a/erts/emulator/beam/erl_trace.c +++ b/erts/emulator/beam/erl_trace.c @@ -151,6 +151,11 @@ do { \ message dispatcher thread takes care of that). */ #define ERTS_GET_TRACER_REF(RES, TPID, TRACEE_FLGS) \ do { (RES) = (TPID); } while(0) +int +erts_is_tracer_proc_valid(Process* p) +{ + return 1; +} #else #define ERTS_NULL_TRACER_REF NULL #define ERTS_TRACER_REF_TYPE Process * @@ -163,6 +168,20 @@ do { \ return; \ } \ } while (0) +int +erts_is_tracer_proc_valid(Process* p) +{ + Process* tracer; + + tracer = erts_proc_lookup(ERTS_TRACER_PROC(p)); + if (tracer && ERTS_TRACE_FLAGS(tracer) & F_TRACER) { + return 1; + } else { + ERTS_TRACER_PROC(p) = NIL; + ERTS_TRACE_FLAGS(p) = ~TRACEE_FLAGS; + return 0; + } +} #endif static Uint active_sched; diff --git a/erts/emulator/beam/erl_trace.h b/erts/emulator/beam/erl_trace.h index 853c6cb0d8..4f2c70d6e7 100644 --- a/erts/emulator/beam/erl_trace.h +++ b/erts/emulator/beam/erl_trace.h @@ -39,6 +39,7 @@ void erts_change_default_tracing(int setflags, Uint *flagsp, Eterm *tracerp); void erts_get_default_tracing(Uint *flagsp, Eterm *tracerp); void erts_set_system_monitor(Eterm monitor); Eterm erts_get_system_monitor(void); +int erts_is_tracer_proc_valid(Process* p); #ifdef ERTS_SMP void erts_check_my_tracer_proc(Process *); -- cgit v1.2.3