[lttng-dev] [RFC] Deprecating RCU signal flavor

Olivier Dion odion at efficios.com
Wed May 10 17:10:27 EDT 2023

Hi all,

We have the intention of deprecating the urcu-signal flavor in the
future.  We are asking users of URCU for _feedback_ on this before
going any further.

Part of this decision is that we are adding support for TSAN in URCU and
the signal flavor deadlocks with TSAN.  It is also my understanding that
the urcu-signal flavor was historically made as a fallback for system
lacking the membarrier(2) system call.  Nowadays, most systems have
support for that system call, making the urcu-signal an artifact of the

The following is a proposed timeline of events:

  1. Asking for feedback from users of URCU (this message)
  2. Disabling the signal flavor by default and adding --enable-flavor-signal
  3. Removing the signal flavor

Olivier Dion
EfficiOS Inc.

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