8f6b846b0a
The ionic device supports a maximum buffer length of 16 bits (see
ionic_rxq_desc or ionic_rxq_sg_elem). When adding new buffers to
the receive rings, the function ionic_rx_fill() uses 16bit math when
calculating the number of pages to allocate for an RX descriptor,
given the interface's MTU setting. If the system PAGE_SIZE >= 64KB,
and the buf_info->page_offset is 0, the remain_len value will never
decrement from the original MTU value and the frag_len value will
always be 0, causing additional pages to be allocated as scatter-
gather elements unnecessarily.
A similar math issue exists in ionic_rx_frags(), but no failures
have been observed here since a 64KB page should not normally
require any scatter-gather elements at any legal Ethernet MTU size.
Fixes: 4b0a7539a372 ("ionic: implement Rx page reuse")
Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.