Using CX-3 virtual functions, either from a bare-metal machine or
pass-through from a VM, MAD packets are proxied through the PF driver.
Since the VF drivers have separate name spaces for MAD Transaction Ids
(TIDs), the PF driver has to re-map the TIDs and keep the book keeping
in a cache.
Following the RDMA Connection Manager (CM) protocol, it is clear when
an entry has to evicted from the cache. When a DREP is sent from
mlx4_ib_multiplex_cm_handler(), id_map_find_del() is called. Similar
when a REJ is received by the mlx4_ib_demux_cm_handler(),
id_map_find_del() is called.
This function wipes out the TID in use from the IDR or XArray and
removes the id_map_entry from the table.
In short, it does everything except the topping of the cake, which is
to remove the entry from the list and free it. In other words, for the
REJ case enumerated above, one id_map_entry will be leaked.
For the other case above, a DREQ has been received first. The
reception of the DREQ will trigger queuing of a delayed work to delete
the id_map_entry, for the case where the VM doesn't send back a DREP.
In the normal case, the VM _will_ send back a DREP, and
id_map_find_del() will be called.
But this scenario introduces a secondary leak. First, when the DREQ is
received, a delayed work is queued. The VM will then return a DREP,
which will call id_map_find_del(). As stated above, this will free the
TID used from the XArray or IDR. Now, there is window where that
particular TID can be re-allocated, lets say by an outgoing REQ. This
TID will later be wiped out by the delayed work, when the function
id_map_ent_timeout() is called. But the id_map_entry allocated by the
outgoing REQ will not be de-allocated, and we have a leak.
Both leaks are fixed by removing the id_map_find_del() function and
only using schedule_delayed(). Of course, a check in
schedule_delayed() to see if the work already has been queued, has
been added.
Another benefit of always using the delayed version for deleting
entries, is that we do get a TimeWait effect; a TID no longer in use,
will occupy the XArray or IDR for CM_CLEANUP_CACHE_TIMEOUT time,
without any ability of being re-used for that time period.
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
---
v1 -> v2:
* Re-factored and removed id_map_find_del
* Fixed a secondary leak
---
drivers/infiniband/hw/mlx4/cm.c | 33 ++++++---------------------------
1 file changed, 6 insertions(+), 27 deletions(-)
diff --git a/drivers/infiniband/hw/mlx4/cm.c b/drivers/infiniband/hw/mlx4/cm.c
index ecd6cadd529a..018449681959 100644
--- a/drivers/infiniband/hw/mlx4/cm.c
+++ b/drivers/infiniband/hw/mlx4/cm.c
@@ -186,23 +186,6 @@ static void id_map_ent_timeout(struct work_struct *work)
kfree(ent);
}
-static void id_map_find_del(struct ib_device *ibdev, int pv_cm_id)
-{
- struct mlx4_ib_sriov *sriov = &to_mdev(ibdev)->sriov;
- struct rb_root *sl_id_map = &sriov->sl_id_map;
- struct id_map_entry *ent, *found_ent;
-
- spin_lock(&sriov->id_map_lock);
- ent = xa_erase(&sriov->pv_id_table, pv_cm_id);
- if (!ent)
- goto out;
- found_ent = id_map_find_by_sl_id(ibdev, ent->slave_id, ent->sl_cm_id);
- if (found_ent && found_ent == ent)
- rb_erase(&found_ent->node, sl_id_map);
-out:
- spin_unlock(&sriov->id_map_lock);
-}
-
static void sl_id_map_add(struct ib_device *ibdev, struct id_map_entry *new)
{
struct rb_root *sl_id_map = &to_mdev(ibdev)->sriov.sl_id_map;
@@ -294,7 +277,7 @@ static void schedule_delayed(struct ib_device *ibdev, struct id_map_entry *id)
spin_lock(&sriov->id_map_lock);
spin_lock_irqsave(&sriov->going_down_lock, flags);
/*make sure that there is no schedule inside the scheduled work.*/
- if (!sriov->is_going_down) {
+ if (!sriov->is_going_down && !id->scheduled_delete) {
id->scheduled_delete = 1;
schedule_delayed_work(&id->timeout, CM_CLEANUP_CACHE_TIMEOUT);
}
@@ -339,11 +322,9 @@ int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id
cont:
set_local_comm_id(mad, id->pv_cm_id);
- if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID)
+ if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID ||
+ mad->mad_hdr.attr_id == CM_DREP_ATTR_ID)
schedule_delayed(ibdev, id);
- else if (mad->mad_hdr.attr_id == CM_DREP_ATTR_ID)
- id_map_find_del(ibdev, pv_cm_id);
-
return 0;
}
@@ -382,12 +363,10 @@ int mlx4_ib_demux_cm_handler(struct ib_device *ibdev, int port, int *slave,
*slave = id->slave_id;
set_remote_comm_id(mad, id->sl_cm_id);
- if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID)
+ if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID ||
+ mad->mad_hdr.attr_id == CM_REJ_ATTR_ID ||
+ mad->mad_hdr.attr_id == CM_DREP_ATTR_ID)
schedule_delayed(ibdev, id);
- else if (mad->mad_hdr.attr_id == CM_REJ_ATTR_ID ||
- mad->mad_hdr.attr_id == CM_DREP_ATTR_ID) {
- id_map_find_del(ibdev, (int) pv_cm_id);
- }
return 0;
}
--
2.20.1
