rds: don't let RDS shutdown a connection while senders are present

This is the first in a long line of patches that tries to fix races
between RDS connection shutdown and RDS traffic.

Here we are maintaining a count of active senders to make sure
the connection doesn't go away while they are using it.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/rds/message.c b/net/rds/message.c
index 96e2bf7dc77e..84f937f11d47 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -81,7 +81,10 @@ static void rds_message_purge(struct rds_message *rm)
 void rds_message_put(struct rds_message *rm)
 {
         rdsdebug("put rm %p ref %d\n", rm, atomic_read(&rm->m_refcount));
-
+        if (atomic_read(&rm->m_refcount) == 0) {
+printk(KERN_CRIT "danger refcount zero on %p\n", rm);
+WARN_ON(1);
+        }
         if (atomic_dec_and_test(&rm->m_refcount)) {
                 BUG_ON(!list_empty(&rm->m_sock_item));
                 BUG_ON(!list_empty(&rm->m_conn_item));