From ea819867b788728aca60717e4fdacb3df771f670 Mon Sep 17 00:00:00 2001 From: Zach Brown Date: Thu, 15 Jul 2010 12:34:33 -0700 Subject: 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 --- net/rds/ib_rdma.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'net/rds/ib_rdma.c') diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c index 0017964f2fcf..8f6e221c9f78 100644 --- a/net/rds/ib_rdma.c +++ b/net/rds/ib_rdma.c @@ -94,8 +94,8 @@ static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr) struct rds_ib_device *rds_ibdev; struct rds_ib_ipaddr *i_ipaddr; - list_for_each_entry(rds_ibdev, &rds_ib_devices, list) { - rcu_read_lock(); + rcu_read_lock(); + list_for_each_entry_rcu(rds_ibdev, &rds_ib_devices, list) { list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) { if (i_ipaddr->ipaddr == ipaddr) { atomic_inc(&rds_ibdev->refcount); @@ -103,8 +103,8 @@ static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr) return rds_ibdev; } } - rcu_read_unlock(); } + rcu_read_unlock(); return NULL; } @@ -761,12 +761,14 @@ void rds_ib_flush_mrs(void) { struct rds_ib_device *rds_ibdev; + down_read(&rds_ib_devices_lock); list_for_each_entry(rds_ibdev, &rds_ib_devices, list) { struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool; if (pool) rds_ib_flush_mr_pool(pool, 0, NULL); } + up_read(&rds_ib_devices_lock); } void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents, -- cgit v1.2.3