rds_send_drop_to() is used during socket tear down to find all the
messages on the socket and flush them . It can race with the
acking code unless it takes the m_rs_lock on each and every message.
This plugs a hole where we didn't take m_rs_lock on any message that
didn't have the RDS_MSG_ON_CONN set. Taking m_rs_lock avoids
double frees and other memory corruptions as the ack code trusts
the message m_rs pointer on a socket that had actually been freed.
We must take m_rs_lock to access m_rs. Because of lock nesting and
rs access, we also need to acquire rs_lock.
Reviewed-by: Ajaykumar Hotchandani <ajaykumar.hotchand...@oracle.com>
Signed-off-by: Santosh Shilimkar <ssant...@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilim...@oracle.com>
---
net/rds/send.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/net/rds/send.c b/net/rds/send.c
index 96ae38d..b0fe412 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -778,8 +778,22 @@ void rds_send_drop_to(struct rds_sock *rs, struct
sockaddr_in *dest)
while (!list_empty(&list)) {
rm = list_entry(list.next, struct rds_message, m_sock_item);
list_del_init(&rm->m_sock_item);
-
rds_message_wait(rm);
+
+ /* just in case the code above skipped this message
+ * because RDS_MSG_ON_CONN wasn't set, run it again here
+ * taking m_rs_lock is the only thing that keeps us
+ * from racing with ack processing.
+ */
+ spin_lock_irqsave(&rm->m_rs_lock, flags);
+
+ spin_lock(&rs->rs_lock);
+ __rds_send_complete(rs, rm, RDS_RDMA_CANCELED);
+ spin_unlock(&rs->rs_lock);
+
+ rm->m_rs = NULL;
+ spin_unlock_irqrestore(&rm->m_rs_lock, flags);
+
rds_message_put(rm);
}
}
--
1.9.1
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