[PATCH rdma-next 1/9] IB/mad: Apply timeout modification (CM MRA) only once

[Leon Romanovsky <leon@kernel.org>]

From: Vlad Dumitrescu <vdumitrescu@nvidia.com>

ib_modify_mad with non-zero timeout is used exclusively for CM MRA [1].
The timeout is computed as the sum of the local timeout (set via
cm_init_av_by_path) and a constant 60s+ Service Timeout
(CMA_CM_MRA_SETTING) passed via the MRA message by the remote.  MRAs are
generated when duplicate messages are received.

Overwriting send_buf.timeout_ms means the MRA Service Timeout requested
by the remote will apply to all remaining retry attempts.  This can lead
to unnecessary and extreme delays when a receiver is only temporarily
overloaded.

Do not save the MRA timeout so that it only applies to the next retry.

ib_modify_mad is also called with a zero timeout, to implement
ib_cancel_mad.  The timeout was also saved in that case, but it is not
required as timeout_sends will skip the retry_send (which reads the
saved value) call anyway, based on the non-successful status.

[1] IBTA v1.7 - Section 12.6.6 - MRA - Message Receipt Acknowledgment

Signed-off-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Reviewed-by: Sean Hefty <shefty@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/mad.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index 86e846b12e2f..bcfbb2a5c02b 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -2623,7 +2623,6 @@ int ib_modify_mad(struct ib_mad_send_buf *send_buf, u32 timeout_ms)
 	if (!timeout_ms)
 		mad_send_wr->status = IB_WC_WR_FLUSH_ERR;
 
-	mad_send_wr->send_buf.timeout_ms = timeout_ms;
 	if (mad_send_wr->state == IB_MAD_STATE_SEND_START ||
 	    (mad_send_wr->state == IB_MAD_STATE_QUEUED && timeout_ms))
 		mad_send_wr->timeout = msecs_to_jiffies(timeout_ms);
-- 
2.47.0