Michael S. Tsirkin 0d4993563b vhost: fix barrier pairing ... According to memory-barriers.txt, an smp memory barrier in guest should always be paired with an smp memory barrier in host, and I quote "a lack of appropriate pairing is almost certainly an error". In case of vhost, failure to flush out used index update before looking at the interrupt disable flag could result in missed interrupts, resulting in networking hang under stress. This might happen when flags read bypasses used index write. So we see interrupts disabled and do not interrupt, at the same time guest writes flags value to enable interrupt, reads an old used index value, thinks that used ring is empty and waits for interrupt. Note: the barrier we pair with here is in drivers/virtio/virtio_ring.c, function vring_enable_cb. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Juan Quintela <quintela@redhat.com>		2010-05-12 18:04:04 +03:00
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Kconfig	net/macvtap: add vhost support	2010-02-18 14:08:38 -08:00
Makefile	vhost_net: a kernel-level virtio server	2010-01-15 01:43:29 -08:00
net.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	2010-03-30 22:02:32 +09:00
vhost.c	vhost: fix barrier pairing	2010-05-12 18:04:04 +03:00
vhost.h	vhost_net: a kernel-level virtio server	2010-01-15 01:43:29 -08:00