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b4e2901c52
There is a race when moving a QP from RTS->CLOSING where a SQ work request could be posted after the FW receives the RDMA_RI/FINI WR. The SQ work request will never get processed, and should be completed with FLUSHED status. Function c4iw_flush_sq(), however was dropping the oldest SQ work request when in CLOSING or IDLE states, instead of completing the pending work request. If that oldest pending work request was actually complete and has a CQE in the CQ, then when that CQE is proceessed in poll_cq, we'll BUG_ON() due to the inconsistent SQ/CQ state. This is a very small timing hole and has only been hit once so far. The fix is two-fold: 1) c4iw_flush_sq() MUST always flush all non-completed WRs with FLUSHED status regardless of the QP state. 2) In c4iw_modify_rc_qp(), always set the "in error" bit on the queue before moving the state out of RTS. This ensures that the state transition will not happen while another thread is in post_rc_send(), because set_state() and post_rc_send() both aquire the qp spinlock. Also, once we transition the state out of RTS, subsequent calls to post_rc_send() will fail because the "in error" bit is set. I don't think this fully closes the race where the FW can get a FINI followed a SQ work request being posted (because they are posted to differente EQs), but the #1 fix will handle the issue by flushing the SQ work request. Signed-off-by: Steve Wise <swise@opengridcomputing.com> Signed-off-by: Roland Dreier <roland@purestorage.com> |
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