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RDMA/irdma: Reduce iWARP QP destroy time

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QP destroy is synchronous and waits for its refcnt to be decremented in
irdma_cm_node_free_cb (for iWARP) which fires after the RCU grace period
elapses.

Applications running a large number of connections are exposed to high
wait times on destroy QP for events like SIGABORT.

The long pole for this wait time is the firing of the call_rcu callback
during a CM node destroy which can be slow. It holds the QP reference
count and blocks the destroy QP from completing.

call_rcu only needs to make sure that list walkers have a reference to the
cm_node object before freeing it and thus need to wait for grace period
elapse. The rest of the connection teardown in irdma_cm_node_free_cb is
moved out of the grace period wait in irdma_destroy_connection. Also,
replace call_rcu with a simple kfree_rcu as it just needs to do a kfree on
the cm_node

Fixes: 146b9756f1 ("RDMA/irdma: Add connection manager")
Link: https://lore.kernel.org/r/20220425181703.1634-3-shiraz.saleem@intel.com
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Shiraz Saleem 2022-04-25 13:17:02 -05:00 committed by Jason Gunthorpe
parent 7b8943b821
commit 2df6d89590
1 changed files with 4 additions and 6 deletions
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10
drivers/infiniband/hw/irdma/cm.c
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@ -2308,10 +2308,8 @@ err:
return NULL;
}
static void irdma_cm_node_free_cb(struct rcu_head *rcu_head)
static void irdma_destroy_connection(struct irdma_cm_node *cm_node)
{
struct irdma_cm_node *cm_node =
container_of(rcu_head, struct irdma_cm_node, rcu_head);
struct irdma_cm_core *cm_core = cm_node->cm_core;
struct irdma_qp *iwqp;
struct irdma_cm_info nfo;
@ -2359,7 +2357,6 @@ static void irdma_cm_node_free_cb(struct rcu_head *rcu_head)
}
cm_core->cm_free_ah(cm_node);
kfree(cm_node);
}
/**
@ -2387,8 +2384,9 @@ void irdma_rem_ref_cm_node(struct irdma_cm_node *cm_node)
spin_unlock_irqrestore(&cm_core->ht_lock, flags);
/* wait for all list walkers to exit their grace period */
call_rcu(&cm_node->rcu_head, irdma_cm_node_free_cb);
irdma_destroy_connection(cm_node);
kfree_rcu(cm_node, rcu_head);
}
/**