xen-netback: use jiffies_64 value to calculate credit timeout
authorWei Liu <wei.liu2@citrix.com>
Mon, 28 Oct 2013 12:07:57 +0000 (12:07 +0000)
committerDavid S. Miller <davem@davemloft.net>
Tue, 29 Oct 2013 04:24:49 +0000 (00:24 -0400)
commit059dfa6a93b779516321e5112db9d7621b1367ba
tree9d8923e95ae5323bcadb17cbf1ee5f57bc9cebbd
parent262e827fe745642589450ae241b7afd3912c3f25
xen-netback: use jiffies_64 value to calculate credit timeout

time_after_eq() only works if the delta is < MAX_ULONG/2.

For a 32bit Dom0, if netfront sends packets at a very low rate, the time
between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2
and the test for timer_after_eq() will be incorrect. Credit will not be
replenished and the guest may become unable to send packets (e.g., if
prior to the long gap, all credit was exhausted).

Use jiffies_64 variant to mitigate this problem for 32bit Dom0.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Jason Luan <jianhai.luan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/xen-netback/common.h
drivers/net/xen-netback/interface.c
drivers/net/xen-netback/netback.c