RDMA/ocrdma: Depend on async link events from CNA

Recently Dough Ledford reported a deadlock happening
between ocrdma-load sequence and NetworkManager service
issuing "open" on be2net interface.

The deadlock happens when any be2net hook (e.g. open/close) is called
in parallel to insmod ocrdma.ko.

A. be2net is sending administrative open/close event to ocrdma holding
   device_list_mutex. It does this from ndo_open/ndo_stop hooks of be2net.
   So sequence of locks is rtnl_lock---> device_list lock

B.  When new ocrdma roce device gets registered, infiniband stack now
    takes rtnl_lock in ib_register_device() in GID initialization routines.
    So sequence of locks in this path is device_list lock ---> rtnl_lock.

This improper locking sequence causes deadlock.

With this patch we stop using administrative open and close events
injected by be2net driver. These events were used to dispatch PORT_ACTIVE
and PORT_ERROR events to the IB-stack. This patch implements a logic
to receive async-link-events generated from CNA whenever link-state-change
is detected. Now on, these async-events will be used to dispatch
PORT_ACTIVE and PORT_ERROR events to IB-stack.

Depending on async-events from CNA removes the need to hold device-list-mutex
and thus breaks the busy-wait scenario.

Reported-by: Doug Ledford <dledford@redhat.com>
CC: Sathya Perla <sathya.perla@avagotech.com>
Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@avagotech.com>
Signed-off-by: Selvin Xavier <selvin.xavier@avagotech.com>
Signed-off-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/ocrdma/ocrdma.h b/drivers/infiniband/hw/ocrdma/ocrdma.h
index ae80590aabdf..040bb8b5cb15 100644
--- a/drivers/infiniband/hw/ocrdma/ocrdma.h
+++ b/drivers/infiniband/hw/ocrdma/ocrdma.h
@@ -232,6 +232,10 @@ struct phy_info {
 	u16 interface_type;
 };
 
+enum ocrdma_flags {
+	OCRDMA_FLAGS_LINK_STATUS_INIT = 0x01
+};
+
 struct ocrdma_dev {
 	struct ib_device ibdev;
 	struct ocrdma_dev_attr attr;
@@ -287,6 +291,7 @@ struct ocrdma_dev {
 	atomic_t update_sl;
 	u16 pvid;
 	u32 asic_id;
+	u32 flags;
 
 	ulong last_stats_time;
 	struct mutex stats_lock; /* provide synch for debugfs operations */
@@ -591,4 +596,9 @@ static inline u8 ocrdma_is_enabled_and_synced(u32 state)
 		(state & OCRDMA_STATE_FLAG_SYNC);
 }
 
+static inline u8 ocrdma_get_ae_link_state(u32 ae_state)
+{
+	return ((ae_state & OCRDMA_AE_LSC_LS_MASK) >> OCRDMA_AE_LSC_LS_SHIFT);
+}
+
 #endif