Removed the reference count from the registrations map.
Although technically supported, registering a single memory
region more than once had a lot of unhandled cases and could
easily lead to a segfault.
RDMA maps require all memory to be unregistered in the same
chunks the memory was registered, which is often impossible
to achieve if a region was registered more than once:
1. register region 0x0 - 0x3 -> it gets mapped to
a single ibv_mr
2. register region 0x1 - 0x2 -> nothing happens, this region
is already registered
3. unregister region 0x0 - 0x3 -> 0x0-0x1 gets unregistered as
one region. 0x2-0x3 gets
unregistered as another
(leading to segfault in the
the current RDMA implementation)
The problem is that the last two regions share the same ibv_mr,
which SPDK tries to free twice. The second free causes a segfault.
vtophys map handles this case by registering each 2MB chunk
separately, but this solution cannot be applied for RDMA, as
NICs put a limitation (~2048) on the number of regions registered.
Another option is to keep a refcount of each ibv_mr allocated,
and free it only when the entire region was unregistered from the
SPDK mem map. This is however very tricky and RDMAmojo mentions
that freeing a memory buffer before unregistering its ibv_mr
may lead to a segfault.
Change-Id: I545c56e24ffa55bda211dea22aeb8a55d9631fe5
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/426085
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
a33e0943b0