tree 4e7f99f47475dfc9343cdb46066e1f515f2bfc0f
parent 6f89dbce8e1134458de8a8e376acaaca4eee602e
author Sowmini Varadhan <sowmini.varadhan@oracle.com> 1518720573 -0800
committer David S. Miller <davem@davemloft.net> 1518815056 -0500

rds: hold a sock ref from rds_message to the rds_sock

The existing model holds a reference from the rds_sock to the
rds_message, but the rds_message does not itself hold a sock_put()
on the rds_sock. Instead the m_rs field in the rds_message is
assigned when the message is queued on the sock, and nulled when
the message is dequeued from the sock.

We want to be able to notify userspace when the rds_message
is actually freed (from rds_message_purge(), after the refcounts
to the rds_message go to 0). At the time that rds_message_purge()
is called, the message is no longer on the rds_sock retransmit
queue. Thus the explicit reference for the m_rs is needed to
send a notification that will signal to userspace that
it is now safe to free/reuse any pages that may have
been pinned down for zerocopy.

This patch manages the m_rs assignment in the rds_message with
the necessary refcount book-keeping.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>