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Nathan Hjelm ab8ed177f5 rcache: fix deadlock in multi-threaded environments
This commit fixes several bugs in the registration cache code:

 - Fix a programming error in the grdma invalidation function that can
   cause an infinite loop if more than 100 registrations are
   associated with a munmapped region. This happens because the
   mca_rcache_base_vma_find_all function returns the same 100
   registrations on each call. This has been fixed by adding an
   iterate function to the vma tree interface.

 - Always obtain the vma lock when needed. This is required because
   there may be other threads in the system even if
   opal_using_threads() is false. Additionally, since it is safe to do
   so (the vma lock is recursive) the vma interface has been made
   thread safe.

 - Avoid calling free() while holding a lock. This avoids race
   conditions with locks held outside the Open MPI code.

Fixes open-mpi/ompi#1654.

Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
2016-05-17 09:02:40 -06:00
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