Fix: sessiond vs consumerd push/get metadata deadlock
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Wed, 19 Aug 2015 21:44:59 +0000 (14:44 -0700)
committerJérémie Galarneau <jeremie.galarneau@efficios.com>
Fri, 4 Sep 2015 22:43:42 +0000 (18:43 -0400)
commitc585821bc78955b3d747fcd733aa1d2b81a3258e
tree5db6b65c20b10a945389ce36844f85bc8d477cc1
parentdf5b86c84d896eb2d74a8757c234492c1d1fc3be
Fix: sessiond vs consumerd push/get metadata deadlock

We need to unlock the registry while we push metadata to break a
circular dependency between the consumerd metadata lock and the sessiond
registry lock. Indeed, pushing metadata to the consumerd awaits that it
gets pushed all the way to relayd, but doing so requires grabbing the
metadata lock. If a concurrent metadata request is being performed by
consumerd, this can try to grab the registry lock on the sessiond while
holding the metadata lock on the consumer daemon. Those push and pull
schemes are performed on two different bidirectionnal communication
sockets.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
src/bin/lttng-sessiond/ust-app.c
src/common/consumer-metadata-cache.c
src/common/consumer-metadata-cache.h
src/common/consumer-timer.c
src/common/consumer-timer.h
src/common/consumer.c
src/common/consumer.h
src/common/kernel-consumer/kernel-consumer.c
src/common/ust-consumer/ust-consumer.c
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