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1900e30d0e
Previously the macb_poll method was checking the RSR register after completing its RX receive work to see if additional packets had been received since IRQs were disabled, since this controller does not maintain the pending IRQ status across IRQ disable. It also had to double-check the register after re-enabling IRQs to detect if packets were received after the first check but before IRQs were enabled. Using the RSR register for this purpose is problematic since it reflects the global device state rather than the per-queue state, so if packets are being received on multiple queues it may end up retriggering receive on a queue where the packets did not actually arrive and not on the one where they did arrive. This will also cause problems with an upcoming change to use NAPI for the TX path where use of multiple queues is more likely. Add a macb_rx_pending function to check the RX ring to see if more packets have arrived in the queue, and use that to check if NAPI should be rescheduled rather than the RSR register. By doing this, we can just ignore the global RSR register entirely, and thus save some extra device register accesses at the same time. This also makes the previous first check for pending packets rather redundant, since it would be checking the RX ring state which was just checked in the receive work function. Therefore we can get rid of it and just check after enabling interrupts whether packets are already pending. Signed-off-by: Robert Hancock <robert.hancock@calian.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.