RDMA/cma: Fix incorrect Packet Lifetime calculation

An approximation for the PacketLifeTime is half the local ACK timeout.
The encoding for both timers are logarithmic.

If the local ACK timeout is set, but zero, it means the timer is
disabled. In this case, we choose the CMA_IBOE_PACKET_LIFETIME value,
since 50% of infinite makes no sense.

Before this commit, the PacketLifeTime became 255 if local ACK
timeout was zero (not running).

Fixed by explicitly testing for timeout being zero.

Fixes: e1ee1e62bec4 ("RDMA/cma: Use ACK timeout for RoCE packetLifeTime")
Link: https://lore.kernel.org/r/1624371207-26710-1-git-send-email-haakon.bugge@oracle.com
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 6b6fa82..9dfb07a 100644 (file)
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -3081,8 +3081,10 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
         * as a reasonable approximation for RoCE networks.
         */
        mutex_lock(&id_priv->qp_mutex);
-       route->path_rec->packet_life_time = id_priv->timeout_set ?
-               id_priv->timeout - 1 : CMA_IBOE_PACKET_LIFETIME;
+       if (id_priv->timeout_set && id_priv->timeout)
+               route->path_rec->packet_life_time = id_priv->timeout - 1;
+       else
+               route->path_rec->packet_life_time = CMA_IBOE_PACKET_LIFETIME;
        mutex_unlock(&id_priv->qp_mutex);
 
        if (!route->path_rec->mtu) {