staging/rdma/hfi: fix CQ completion order issue
The current implementation of the sdma_wait variable has a timing hole that can cause a completion Q entry to be returned from a pio send prior to an older sdma packets completion queue entry. The sdma_wait variable used to be decremented prior to calling the packet complete routine. The hole is between decrement and the verbs completion where send engine using pio could return a out of order completion in that window. This patch closes the hole by allowing an API option to specify an sdma_drained callback. The atomic dec is positioned after the complete callback to avoid the window as long as the pio path doesn't execute when there is a non-zero sdma count. Reviewed-by: NJubin John <jubin.john@intel.com> Signed-off-by: NDean Luick <dean.luick@intel.com> Signed-off-by: NMike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: NDoug Ledford <dledford@redhat.com>
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