IB/core: Don't register each MAD agent for LSM notifier

When creating many MAD agents in a short period of time, receive packet
processing can be delayed long enough to cause timeouts while new agents
are being added to the atomic notifier chain with IRQs disabled.  Notifier
chain registration and unregstration is an O(n) operation. With large
numbers of MAD agents being created and destroyed simultaneously the CPUs
spend too much time with interrupts disabled.

Instead of each MAD agent registering for it's own LSM notification,
maintain a list of agents internally and register once, this registration
already existed for handling the PKeys. This list is write mostly, so a
normal spin lock is used vs a read/write lock. All MAD agents must be
checked, so a single list is used instead of breaking them down per
device.

Notifier calls are done under rcu_read_lock, so there isn't a risk of
similar packet timeouts while checking the MAD agents security settings
when notified.

Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h
index bcb3e3029a9b..d053110207eb 100644
--- a/drivers/infiniband/core/core_priv.h
+++ b/drivers/infiniband/core/core_priv.h
@@ -202,6 +202,7 @@ int ib_mad_agent_security_setup(struct ib_mad_agent *agent,
 				enum ib_qp_type qp_type);
 void ib_mad_agent_security_cleanup(struct ib_mad_agent *agent);
 int ib_mad_enforce_security(struct ib_mad_agent_private *map, u16 pkey_index);
+void ib_mad_agent_security_change(void);
 #else
 static inline void ib_security_destroy_port_pkey_list(struct ib_device *device)
 {
@@ -267,6 +268,10 @@ static inline int ib_mad_enforce_security(struct ib_mad_agent_private *map,
 {
 	return 0;
 }
+
+static inline void ib_mad_agent_security_change(void)
+{
+}
 #endif
 
 struct ib_device *ib_device_get_by_index(u32 ifindex);