RDS/IB: protect the list of IB devices
The RDS IB device list wasn't protected by any locking. Traversal in
both the get_mr and FMR flushing paths could race with additon and
removal.
List manipulation is done with RCU primatives and is protected by the
write side of a rwsem. The list traversal in the get_mr fast path is
protected by a rcu read critical section. The FMR list traversal is
more problematic because it can block while traversing the list. We
protect this with the read side of the rwsem.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
diff --git a/net/rds/ib.h b/net/rds/ib.h
index a13ced5..2189fd4 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -23,6 +23,7 @@
#define RDS_IB_RECYCLE_BATCH_COUNT 32
+extern struct rw_semaphore rds_ib_devices_lock;
extern struct list_head rds_ib_devices;
/*