diff options
author | Alexander Kabaev <kan@freebsd.org> | 2019-11-01 18:26:20 -0400 |
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committer | Alexander Kabaev <kan@freebsd.org> | 2019-11-01 21:57:49 -0400 |
commit | feda545105106d673fdca61028331c86eeb1f408 (patch) | |
tree | 74cb9790744d3f73ac6145910543196bf7ee5c9c /src/vnet/l2tp | |
parent | 5bec5f7860dafcef6aefd50b74de15d08910c6f4 (diff) |
vlib: Handle race in thread barrier processing
When CLIB_DEBUG is enabled, vlib_foreach_main macro asserts that
vlib_main it currently looks at is safely parked in barrier, by
checkling that vlib_main->parked_at_barrier is not 0.
Unfortunately, the check is racy - workers first increment the
atomic counter to indicate that they have reached the barrier
and _then_ set this_main->parked_at_barrier to 1. For the last
worker to suspend this opens the race - main thread is free
to execute and assert immediately after atomic counter has been
incremented, before worker gets to write to own parked_at_barrier.
Fix this by simply swapping the order of two operations.
Type: fix
Signed-off-by: Alexnader Kabaev <kan@FreeBSD.org>
Change-Id: Iae47abd6ca0be1c5413f5ecaefabc64cd7eac2ed
Diffstat (limited to 'src/vnet/l2tp')
0 files changed, 0 insertions, 0 deletions