btl/vader: ensure that the send tag is always written last #5696
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To ensure fast box entries are complete when processed by the receiving process the tag must be written last. This includes a zero header for the next fast box entry (in some cases). This commit fixes two instances where the tag was written too early. In one case, on 32-bit systems it is possible for the tag part of the header to be written before the size. The second instance is an ordering issue. The zero header was being written after the fastbox header. Fixes open-mpi#5375, open-mpi#5638 Signed-off-by: Nathan Hjelm <[email protected]>
This was referenced Sep 14, 2018
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In talking to @hjelmn in IM, he points out that this bug is not silent data corruption, but rather will just cause a hang or crash. It's still a pretty serious bug, but at least it's not silent data corruption. |
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To ensure fast box entries are complete when processed by the
receiving process the tag must be written last. This includes a zero
header for the next fast box entry (in some cases). This commit fixes
two instances where the tag was written too early. In one case, on
32-bit systems it is possible for the tag part of the header to be
written before the size. The second instance is an ordering issue. The
zero header was being written after the fastbox header.
Fixes #5375, #5638
Signed-off-by: Nathan Hjelm [email protected]