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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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.