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authorWei Liu <wei.liu2@citrix.com>2013-10-28 12:07:57 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-20 12:27:46 -0800
commitfb1494fa72c8f40f63c56b0f0e77ea40db586448 (patch)
tree5da662ee603de9d3506f570533beff72a3d01a79
parent0b5be4967ce4d66e2f23103aa114e8170546578e (diff)
downloadvexpress-lsk-fb1494fa72c8f40f63c56b0f0e77ea40db586448.tar.gz
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/xen-netback/common.h1
-rw-r--r--drivers/net/xen-netback/interface.c3
-rw-r--r--drivers/net/xen-netback/netback.c10
3 files changed, 7 insertions, 7 deletions
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 1a285083d24..f2faa779e3f 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -88,6 +88,7 @@ struct xenvif {
unsigned long credit_usec;
unsigned long remaining_credit;
struct timer_list credit_timeout;
+ u64 credit_window_start;
/* Statistics */
unsigned long rx_gso_checksum_fixup;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 3a294c2528d..c4a2eb2cd8a 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -275,8 +275,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
vif->credit_bytes = vif->remaining_credit = ~0UL;
vif->credit_usec = 0UL;
init_timer(&vif->credit_timeout);
- /* Initialize 'expires' now: it's used to track the credit window. */
- vif->credit_timeout.expires = jiffies;
+ vif->credit_window_start = get_jiffies_64();
dev->netdev_ops = &xenvif_netdev_ops;
dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 0071f211a08..36efb418c26 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1423,9 +1423,8 @@ out:
static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
{
- unsigned long now = jiffies;
- unsigned long next_credit =
- vif->credit_timeout.expires +
+ u64 now = get_jiffies_64();
+ u64 next_credit = vif->credit_window_start +
msecs_to_jiffies(vif->credit_usec / 1000);
/* Timer could already be pending in rare cases. */
@@ -1433,8 +1432,8 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
return true;
/* Passed the point where we can replenish credit? */
- if (time_after_eq(now, next_credit)) {
- vif->credit_timeout.expires = now;
+ if (time_after_eq64(now, next_credit)) {
+ vif->credit_window_start = now;
tx_add_credit(vif);
}
@@ -1446,6 +1445,7 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
tx_credit_callback;
mod_timer(&vif->credit_timeout,
next_credit);
+ vif->credit_window_start = next_credit;
return true;
}