]> git.karo-electronics.de Git - linux-beck.git/commit
xen-netback: stop vif thread spinning if frontend is unresponsive
authorPaul Durrant <Paul.Durrant@citrix.com>
Wed, 8 Jan 2014 12:41:58 +0000 (12:41 +0000)
committerDavid S. Miller <davem@davemloft.net>
Fri, 10 Jan 2014 04:05:46 +0000 (23:05 -0500)
commit11b57f90257c1d6a91cee720151b69e0c2020cf6
tree6da4cdb6bbaf71ab38ad9a133e2391aa4910f32a
parent451cd14e082c631aeaec37bfa872d3fa594d1845
xen-netback: stop vif thread spinning if frontend is unresponsive

The recent patch to improve guest receive side flow control (ca2f09f2) had a
slight flaw in the wait condition for the vif thread in that any remaining
skbs in the guest receive side netback internal queue would prevent the
thread from sleeping. An unresponsive frontend can lead to a permanently
non-empty internal queue and thus the thread will spin. In this case the
thread should really sleep until the frontend becomes responsive again.

This patch adds an extra flag to the vif which is set if the shared ring
is full and cleared when skbs are drained into the shared ring. Thus,
if the thread runs, finds the shared ring full and can make no progress the
flag remains set. If the flag remains set then the thread will sleep,
regardless of a non-empty queue, until the next event from the frontend.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/xen-netback/common.h
drivers/net/xen-netback/netback.c