LTTng » LTTng-tools

The last lines of lttng-sessiond -vvv are:

DEBUG1 [4449/4501]: Spawning consumerd (in spawn_consumerd() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:2153)
DEBUG2 [4449/4501]: Consumer pid 4510 (in start_consumerd() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:2339)
DEBUG2 [4449/4501]: Spawning consumer control thread (in start_consumerd() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:2342)
DEBUG1 [4449/4511]: [thread] Manage consumer started (in thread_manage_consumer() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:992)
DEBUG1 [4510/4510]: Using 32-bit UST consumer at: /usr/local/lttng-sabrelite-mel/lib/lttng/libexec/lttng-consumerd (in spawn_consumerd() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:2275)
DEBUG2 [4449/4511]: Receiving code from consumer err_sock (in thread_manage_consumer() at ../../../../lttng-tools/src/bin/lttng-sessiond/main.c:1077)
Warning: No tracing group detected

Apparently the crash happens at main.c:1244, because "consumer_data->metadata_sock.fd_ptr" is NULL so the dereference causes the crash.

I'm investigating further, FWIW.

In fact, just visually inspecting the "thread_manage_consumer" function, I notice that consumer_data->metadata_sock.fd_ptr is initialized at line 1100 only. There are, however, "goto" statements to "error" et al. before that point, so it seems entirely possible to end up in line 1244 with the fd_ptr not being initialized.

I'll try to confirm that this is in fact what crashes the app tomorrow.