[PATCH v2 0/2] interrupt epoll event handling

[Kevin Traynor <ktraynor@redhat.com>]

These patches are to fix some issues with epoll event handling for
EPOLLERR/EPOLLRDHUP/EPOLLHUP.

In the interrupt handling code, some interrupts are read directly in eal
and some just call registered callback which will read the interrupt.

v1 version was too aggressively dealing with epoll disconnect/error events
by detecting and removing the interrupt in the eal interrupt code and
not calling the registered callbacks.

This was a problem for virtio, which needs to handle these scenarios
itself so it can enable reconnect for vhost server.

In v2, if the read is not done in eal then the registered callback will
be called and it is up to handlers external to eal to deal with the
interrupt as they see fit.

This better respects interrupt types like RTE_INTR_HANDLE_EXT and
RTE_INTR_HANDLE_VDEV.

To deal with the observed issue of mlx5 devx interrupts causing a
busy-loop and 100% CPU of dpdk-intr thread, extra handling is added to
the devx interrupt handler.

1/2: deals with mlx5 devx interrupt busy-loop
2/2: deals with disconnect/error epoll events for interrupts read in eal

The patches are independent but 1/2 is the direct fix for the real life
bug observed and reported in https://bugs.dpdk.org/show_bug.cgi?id=1873.

Kevin Traynor (2):
  net/mlx5: check for no data read in devx interrupt
  eal/linux: handle interrupt epoll events

 drivers/net/mlx5/linux/mlx5_ethdev_os.c | 34 ++++++++++---
 lib/eal/linux/eal_interrupts.c          | 67 ++++++++++++++++---------
 2 files changed, 72 insertions(+), 29 deletions(-)

-- 
2.52.0