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Fix tracing of BIFs for multiple trace sessions #10349

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311efb6
erts: Fix handling of Export.is_bif_traced for multi sessions
sverker Oct 23, 2025
a26f3ac
fixup! erts: Fix handling of Export.is_bif_traced for multi sessions
sverker Nov 5, 2025
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5 changes: 1 addition & 4 deletions erts/emulator/beam/beam_bif_load.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2237,10 +2237,7 @@ delete_code(Module* modp)
}
}

if (ep->bif_number != -1 && ep->is_bif_traced) {
/* Code unloading kills both global and local call tracing. */
ep->is_bif_traced = 0;
}
ASSERT(!ep->is_bif_traced);

ep->trampoline.common.op = BeamOpCodeAddr(op_call_error_handler);
ep->trampoline.not_loaded.deferred = 0;
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56 changes: 51 additions & 5 deletions erts/emulator/beam/beam_bp.c
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Expand Up @@ -299,8 +299,36 @@ erts_bp_free_matched_functions(BpFunctions* f)
else ASSERT(f->matched == 0);
}

void
erts_consolidate_export_bp_data(BpFunctions* f)
/*
* Set Export.is_bif_traced for BIFs
* to true if breakpoint exist in either export trampoline or code
* to false otherwise.
*/
static void set_export_is_bif_traced(Export *ep)
{
ErtsCodePtr code;
const ErtsCodeInfo *ci;

if (ep->bif_number < 0) {
ASSERT(!ep->is_bif_traced);
return;
}

if (ep->info.gen_bp && ep->is_bif_traced) {
return;
}

code = ep->dispatch.addresses[erts_active_code_ix()];
ci = erts_code_to_codeinfo(code);
ASSERT(ci->mfa.module == ep->info.mfa.module);
ASSERT(ci->mfa.function == ep->info.mfa.function);
ASSERT(ci->mfa.arity == ep->info.mfa.arity);

ep->is_bif_traced = (ep->info.gen_bp || ci->gen_bp);
}

static void
consolidate_export_bp_data(BpFunctions* f)
{
BpFunction* fs = f->matching;
Uint i, n;
Expand All @@ -324,6 +352,8 @@ erts_consolidate_export_bp_data(BpFunctions* f)
mi->code_length));

consolidate_bp_data(mi, ci_rw, 0);

set_export_is_bif_traced(ErtsContainerStruct(ci_rw, Export, info));
}
}

Expand Down Expand Up @@ -365,6 +395,19 @@ erts_consolidate_local_bp_data(BpFunctions* f)
}
}

void
erts_consolidate_all_bp_data(BpFunctions* f, BpFunctions* e)
{
erts_consolidate_local_bp_data(f);
/*
* Must do export entries *after* module code
* so breakpoints in code have been cleared and
* Export.is_bif_traced can be updated accordingly.
*/
consolidate_export_bp_data(e);
}


void
erts_free_breakpoints(void)
{
Expand All @@ -387,7 +430,7 @@ consolidate_bp_data(struct erl_module_instance *mi,

g = ci_rw->gen_bp;
if (!g) {
return;
return;
}

prev_p = &ci_rw->gen_bp;
Expand Down Expand Up @@ -710,9 +753,12 @@ erts_set_mtrace_break(BpFunctions* f, Binary *match_spec, ErtsTracer tracer)
}

void
erts_set_export_trace(ErtsCodeInfo *ci, Binary *match_spec)
erts_set_export_trace(Export* ep, Binary *match_spec)
{
set_function_break(ci, match_spec, ERTS_BPF_GLOBAL_TRACE, 0, erts_tracer_nil);
set_function_break(&ep->info, match_spec, ERTS_BPF_GLOBAL_TRACE, 0,
erts_tracer_nil);

set_export_is_bif_traced(ep);
}

void
Expand Down
4 changes: 2 additions & 2 deletions erts/emulator/beam/beam_bp.h
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Expand Up @@ -142,13 +142,13 @@ Uint erts_sum_all_session_flags(ErtsCodeInfo *ci_rw);
void erts_uninstall_breakpoints(BpFunctions* f);

void erts_consolidate_local_bp_data(BpFunctions* f);
void erts_consolidate_export_bp_data(BpFunctions* f);
void erts_consolidate_all_bp_data(BpFunctions* f, BpFunctions* e);
void erts_free_breakpoints(void);

void erts_set_trace_break(BpFunctions *f, Binary *match_spec);
void erts_clear_trace_break(BpFunctions *f);

void erts_set_export_trace(ErtsCodeInfo *ci, Binary *match_spec);
void erts_set_export_trace(Export *ep, Binary *match_spec);
void erts_clear_export_trace(ErtsCodeInfo *ci);

void erts_set_mtrace_break(BpFunctions *f, Binary *match_spec, ErtsTracer tracer);
Expand Down
98 changes: 46 additions & 52 deletions erts/emulator/beam/erl_bif_trace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2387,54 +2387,13 @@ erts_set_trace_pattern(ErtsCodeMFA *mfa, int specified,
ErtsTracer meta_tracer, int is_blocking)
{
const ErtsCodeIndex code_ix = erts_active_code_ix();
Uint i, n, matches;
Uint i, n;
Uint matches = 0;
BpFunction* fp;

erts_bp_match_export(&finish_bp.e, mfa, specified);

fp = finish_bp.e.matching;
n = finish_bp.e.matched;
matches = 0;

for (i = 0; i < n; i++) {
ErtsCodeInfo *ci_rw;
Export* ep;

/* Export entries are always writable, discard const. */
ci_rw = (ErtsCodeInfo *)fp[i].code_info;
ep = ErtsContainerStruct(ci_rw, Export, info);

if (ep->bif_number != -1) {
ep->is_bif_traced = !!on;
}

if (on && !flags.breakpoint) {
/* Turn on global call tracing */
if (!erts_is_export_trampoline_active(ep, code_ix)) {
fp[i].mod->curr.num_traced_exports++;
#if defined(DEBUG) && !defined(BEAMASM)
ep->info.u.op = BeamOpCodeAddr(op_i_func_info_IaaI);
#endif
ep->trampoline.breakpoint.op = BeamOpCodeAddr(op_i_generic_breakpoint);
ep->trampoline.breakpoint.address =
(BeamInstr) ep->dispatch.addresses[code_ix];
}
erts_set_export_trace(ci_rw, match_prog_set);

} else if (!on && flags.breakpoint) {
/* Turn off breakpoint tracing -- nothing to do here. */
} else {
/*
* Turn off global tracing, either explicitly or implicitly
* before turning on breakpoint tracing.
*/
erts_clear_export_trace(ci_rw);
}
}

/*
** So, now for code breakpoint tracing
*/
* First do "local" code breakpoint tracing
*/
erts_bp_match_functions(&finish_bp.f, mfa, specified);

if (on) {
Expand Down Expand Up @@ -2476,6 +2435,47 @@ erts_set_trace_pattern(ErtsCodeMFA *mfa, int specified,
}
}

/*
* Do export entries after module code so breakpoints have been set
* and Export.is_bif_traced can be updated accordingly.
*/
erts_bp_match_export(&finish_bp.e, mfa, specified);

fp = finish_bp.e.matching;
n = finish_bp.e.matched;

for (i = 0; i < n; i++) {
ErtsCodeInfo *ci_rw;
Export* ep;

/* Export entries are always writable, discard const. */
ci_rw = (ErtsCodeInfo *)fp[i].code_info;
ep = ErtsContainerStruct(ci_rw, Export, info);

if (on && !flags.breakpoint) {
/* Turn on global call tracing */
if (!erts_is_export_trampoline_active(ep, code_ix)) {
fp[i].mod->curr.num_traced_exports++;
#if defined(DEBUG) && !defined(BEAMASM)
ep->info.u.op = BeamOpCodeAddr(op_i_func_info_IaaI);
#endif
ep->trampoline.breakpoint.op = BeamOpCodeAddr(op_i_generic_breakpoint);
ep->trampoline.breakpoint.address =
(BeamInstr) ep->dispatch.addresses[code_ix];
}
erts_set_export_trace(ep, match_prog_set);

} else if (!on && flags.breakpoint) {
/* Turn off breakpoint tracing -- nothing to do here. */
} else {
/*
* Turn off global tracing, either explicitly or implicitly
* before turning on breakpoint tracing.
*/
erts_clear_export_trace(ci_rw);
}
}

finish_bp.current = 0;
finish_bp.install = on;
finish_bp.local = flags.breakpoint;
Expand Down Expand Up @@ -2515,15 +2515,10 @@ prepare_clear_all_trace_pattern(ErtsTraceSession* session)

for (i = 0; i < n; i++) {
ErtsCodeInfo *ci_rw;
Export* ep;

/* Export entries are always writable, discard const. */
ci_rw = (ErtsCodeInfo *)fp[i].code_info;
ep = ErtsContainerStruct(ci_rw, Export, info);

if (ep->bif_number != -1) {
ep->is_bif_traced = 0; // ToDo: multi sessions?
}
erts_clear_export_trace(ci_rw);
}

Expand Down Expand Up @@ -2686,8 +2681,7 @@ erts_finish_breakpointing(void)
* deallocate the GenericBp structs for them.
*/
clean_export_entries(&finish_bp.e);
erts_consolidate_export_bp_data(&finish_bp.e);
erts_consolidate_local_bp_data(&finish_bp.f);
erts_consolidate_all_bp_data(&finish_bp.f, &finish_bp.e);
erts_bp_free_matched_functions(&finish_bp.e);
erts_bp_free_matched_functions(&finish_bp.f);
consolidate_event_tracing(erts_staging_trace_session->send_tracing);
Expand Down
76 changes: 76 additions & 0 deletions erts/emulator/test/trace_session_SUITE.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@
destroy/1,
negative/1,
error_info/1,
is_bif_traced/1,

end_of_list/1]).

-include_lib("common_test/include/ct.hrl").
Expand Down Expand Up @@ -72,6 +74,8 @@ all() ->
destroy,
negative,
error_info,
is_bif_traced,

end_of_list].

init_per_suite(Config) ->
Expand Down Expand Up @@ -1634,6 +1638,78 @@ tracer_loop(Name, Tester) ->
tracer_loop(Name, Tester).


%% OTP-19840: Verify setting/clearing of 'is_bif_traced' in export entry
%% works correctly for multiple sessions.
is_bif_traced(_Config) ->
CallTypes = [global, local],
[is_bif_traced_do(CT1, CT2, CT3)
|| CT1 <- CallTypes, CT2 <- CallTypes, CT3 <- CallTypes],
ok.

is_bif_traced_do(CT1, CT2, CT3) ->
Tester = self(),
TracerFun = fun F() -> receive M -> Tester ! {self(), M} end, F() end,
T1 = spawn_link(TracerFun),
S1 = trace:session_create(one, T1, []),
trace:function(S1, {erlang,display,1}, true, [CT1]),
trace:process(S1, self(), true, [call]),

erlang:display("S1"),
{T1, {trace,Tester,call,{erlang,display,["S1"]}}} = receive_any(),

T2 = spawn_link(TracerFun),
S2 = trace:session_create(two, T2, []),
trace:function(S2, {erlang,display,1}, true, [CT2]),
trace:process(S2, self(), true, [call]),

erlang:display("S1 & S2"),
receive_parallel_list(
[[{T1, {trace,Tester,call,{erlang,display,["S1 & S2"]}}}],
[{T2, {trace,Tester,call,{erlang,display,["S1 & S2"]}}}]]),

T3 = spawn_link(TracerFun),
S3 = trace:session_create(three, T3, []),
trace:function(S3, {erlang,display,1}, true, [CT3]),
trace:process(S3, self(), true, [call]),

erlang:display("S1 & S2 & S3"),
receive_parallel_list(
[[{T1, {trace,Tester,call,{erlang,display,["S1 & S2 & S3"]}}}],
[{T2, {trace,Tester,call,{erlang,display,["S1 & S2 & S3"]}}}],
[{T3, {trace,Tester,call,{erlang,display,["S1 & S2 & S3"]}}}]]),

%% Remove not last BIF trace nicely
trace:function(S1, {erlang,display,1}, false, [CT1]),
erlang:display("S2 & S3"),
receive_parallel_list(
[[{T2, {trace,Tester,call,{erlang,display,["S2 & S3"]}}}],
[{T3, {trace,Tester,call,{erlang,display,["S2 & S3"]}}}]]),

%% Remove not last BIF trace by session destruction
trace:session_destroy(S2),
erlang:display("S3"),
receive_parallel_list(
[[{T3, {trace,Tester,call,{erlang,display,["S3"]}}}]]),

%% Remove last BIF trace nicely
trace:function(S3, {erlang,display,1}, false, [CT3]),
erlang:display("no trace"),
timeout = receive_any(),

trace:function(S1, {erlang,display,1}, true, [CT1]),
erlang:display("S1"),
receive_parallel_list(
[[{T1, {trace,Tester,call,{erlang,display,["S1"]}}}]]),

%% Remove last BIF trace by session destruction
trace:session_destroy(S1),
erlang:display("no trace"),
timeout = receive_any(),

trace:session_destroy(S3),
ok.


receive_any() ->
receive_any(1000).

Expand Down
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