From: Wei Liu <wei.liu2@citrix.com>
Date: Mon, 28 Oct 2013 12:07:57 +0000 (+0000)
Subject: xen-netback: use jiffies_64 value to calculate credit timeout
X-Git-Tag: v3.2.53~58
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5e14dc9525b13e69991e577d9c6e0d768b1fe29c;p=pandora-kernel.git

xen-netback: use jiffies_64 value to calculate credit timeout

[ Upstream commit 059dfa6a93b779516321e5112db9d7621b1367ba ]

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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