net/smc: fix sender_free computation

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In some scenarios a separate consumer cursor update is necessary.
The decision is made in smc_tx_consumer_cursor_update(). The
sender_free computation could be wrong:

The rx confirmed cursor is always smaller than or equal to the
rx producer cursor. The parameters in the smc_curs_diff() call
have to be exchanged, otherwise sender_free might even be negative.

And if more data arrives local_rx_ctrl.prod might be updated, enabling
a cursor difference between local_rx_ctrl.prod and rx confirmed cursor
larger than the RMB size. This case is not covered by smc_curs_diff().
Thus function smc_curs_diff_large() is introduced here.

If a recvmsg() is processed in parallel, local_tx_ctrl.cons might
change during smc_cdc_msg_send. Make sure rx_curs_confirmed is updated
with the actually sent local_tx_ctrl.cons value.

Fixes: e82f2e31f5 ("net/smc: optimize consumer cursor updates")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

Ursula Braun 2019-02-04 13:44:45 +01:00 • committed by David S. Miller

parent ad6f317f72

commit b8649efad8

3 changed files with 30 additions and 4 deletions

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5

net/smc/smc_cdc.c

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26

net/smc/smc_cdc.h

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3

net/smc/smc_tx.c

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