Fix: racy notifier captures update vs traversal

[lttng-modules.git] / include / lttng / tracepoint-event-impl.h

diff --git a/include/lttng/tracepoint-event-impl.h b/include/lttng/tracepoint-event-impl.h
index 079d7d37006e9e677f1ae5d16d33e680378993f7..f5464773cd47fb1e0059ccda2df9ccc6c33feaed 100644 (file)
--- a/include/lttng/tracepoint-event-impl.h
+++ b/include/lttng/tracepoint-event-impl.h
@@ -1430,6 +1430,8 @@ static void __event_notifier_probe__##_name(void *__data, _proto)       \
        struct probe_local_vars __tp_locvar;                                  \
        struct probe_local_vars *tp_locvar __attribute__((unused)) =          \
                        &__tp_locvar;                                         \
+       struct lttng_kernel_notifier_ctx __notif_ctx;                         \
+       bool __interpreter_stack_prepared = false;                            \
                                                                              \
        if (unlikely(!READ_ONCE(__event_notifier->enabled)))                  \
                return;                                                       \
@@ -1440,6 +1442,7 @@ static void __event_notifier_probe__##_name(void *__data, _proto)       \
                                                                              \
                __event_prepare_interpreter_stack__##_name(__stackvar.__interpreter_stack_data, \
                                tp_locvar, _args);                            \
+               __interpreter_stack_prepared = true;                          \
                lttng_list_for_each_entry_rcu(bc_runtime, &__event_notifier->filter_bytecode_runtime_head, node) { \
                        if (unlikely(bc_runtime->interpreter_funcs.filter(bc_runtime, &__lttng_probe_ctx,       \
                                        __stackvar.__interpreter_stack_data) & LTTNG_INTERPRETER_RECORD_FLAG))  \
@@ -1449,14 +1452,16 @@ static void __event_notifier_probe__##_name(void *__data, _proto)             \
                        goto __post;                                          \
        }                                                                     \
                                                                              \
-       if (unlikely(!list_empty(&__event_notifier->capture_bytecode_runtime_head)))    \
+       __notif_ctx.eval_capture = LTTNG_READ_ONCE(__event_notifier->eval_capture); \
+       if (unlikely(!__interpreter_stack_prepared && __notif_ctx.eval_capture)) \
                __event_prepare_interpreter_stack__##_name(                   \
                                __stackvar.__interpreter_stack_data,          \
                                tp_locvar, _args);                            \
                                                                              \
        __event_notifier->send_notification(__event_notifier,                 \
                        &__lttng_probe_ctx,                                   \
-                       __stackvar.__interpreter_stack_data);                 \
+                       __stackvar.__interpreter_stack_data,                  \
+                       &__notif_ctx);                                        \
                                                                              \
 __post:                                                                              \
        _code_post                                                            \
@@ -1481,6 +1486,8 @@ static void __event_notifier_probe__##_name(void *__data)               \
        struct probe_local_vars __tp_locvar;                                  \
        struct probe_local_vars *tp_locvar __attribute__((unused)) =          \
                        &__tp_locvar;                                         \
+       struct lttng_kernel_notifier_ctx __notif_ctx;                         \
+       bool __interpreter_stack_prepared = false;                            \
                                                                              \
        if (unlikely(!READ_ONCE(__event_notifier->enabled)))                  \
                return;                                                       \
@@ -1491,6 +1498,7 @@ static void __event_notifier_probe__##_name(void *__data)               \
                                                                              \
                __event_prepare_interpreter_stack__##_name(__stackvar.__interpreter_stack_data, \
                                tp_locvar);                                   \
+               __interpreter_stack_prepared = true;                          \
                lttng_list_for_each_entry_rcu(bc_runtime, &__event_notifier->filter_bytecode_runtime_head, node) { \
                        if (unlikely(bc_runtime->interpreter_funcs.filter(bc_runtime, &__lttng_probe_ctx,       \
                                        __stackvar.__interpreter_stack_data) & LTTNG_INTERPRETER_RECORD_FLAG))  \
@@ -1500,14 +1508,16 @@ static void __event_notifier_probe__##_name(void *__data)                     \
                        goto __post;                                          \
        }                                                                     \
                                                                              \
-       if (unlikely(!list_empty(&__event_notifier->capture_bytecode_runtime_head)))  \
+       __notif_ctx.eval_capture = LTTNG_READ_ONCE(__event_notifier->eval_capture); \
+       if (unlikely(!__interpreter_stack_prepared && __notif_ctx.eval_capture)) \
                __event_prepare_interpreter_stack__##_name(                   \
                                __stackvar.__interpreter_stack_data,          \
                                tp_locvar);                                   \
                                                                              \
        __event_notifier->send_notification(__event_notifier,                 \
                        &__lttng_probe_ctx,                                   \
-                       __stackvar.__interpreter_stack_data);                 \
+                       __stackvar.__interpreter_stack_data,                  \
+                       &__notif_ctx);                                        \
 __post:                                                                              \
        _code_post                                                            \
        return;                                                               \