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  1. 11 Apr, 2014 4 commits
    • Steve Wise's avatar
      RDMA/cxgb4: SQ flush fix · b4e2901c
      Steve Wise authored 
      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: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
      b4e2901c
    • Steve Wise's avatar
      RDMA/cxgb4: rmb() after reading valid gen bit · def4771f
      Steve Wise authored 
      Some HW platforms can reorder read operations, so we must rmb() after
we see a valid gen bit in a CQE but before we read any other fields
from the CQE.
Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
      def4771f
    • Steve Wise's avatar
      RDMA/cxgb4: Endpoint timeout fixes · b33bd0cb
      Steve Wise authored 
      1) timedout endpoint processing can be starved. If there are continual
   CPL messages flowing into the driver, the endpoint timeout
   processing can be starved.  This condition exposed the other bugs
   below.

Solution: In process_work(), call process_timedout_eps() after each CPL
is processed.

2) Connection events can be processed even though the endpoint is on
   the timeout list.  If the endpoint is scheduled for timeout
   processing, then we must ignore MPA Start Requests and Replies.

Solution: Change stop_ep_timer() to return 1 if the ep has already been
queued for timeout processing.  All the callers of stop_ep_timer() need
to check this and act accordingly.  There are just a few cases where
the caller needs to do something different if stop_ep_timer() returns 1:

1) in process_mpa_reply(), ignore the reply and  process_timeout()
   will abort the connection.

2) in process_mpa_request, ignore the request and process_timeout()
   will abort the connection.

It is ok for callers of stop_ep_timer() to abort the connection since
that will leave the state in ABORTING or DEAD, and process_timeout()
now ignores timeouts when the ep is in these states.

3) Double insertion on the timeout list.  Since the endpoint timers
   are used for connection setup and teardown, we need to guard
   against the possibility that an endpoint is already on the timeout
   list.  This is a rare condition and only seen under heavy load and
   in the presense of the above 2 bugs.

Solution: In ep_timeout(), don't queue the endpoint if it is already on
the queue.
Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
      b33bd0cb
    • Steve Wise's avatar
      RDMA/cxgb4: Use the BAR2/WC path for kernel QPs and T5 devices · fa658a98
      Steve Wise authored 
      Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>

[ Fix cast from u64* to integer.  - Roland ]
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
      fa658a98
  3. 03 Apr, 2014 36 commits
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