From: Wei Liu Date: Mon, 28 Oct 2013 12:07:57 +0000 (+0000) Subject: xen-netback: use jiffies_64 value to calculate credit timeout X-Git-Tag: v3.11.9~21 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f54c27651df94b564dec0d66954ed190c8ef811;p=thirdparty%2Fkernel%2Fstable.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 Signed-off-by: Wei Liu Reviewed-by: David Vrabel Cc: Ian Campbell Cc: Jason Luan Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 4d9a5e70c992c..b2d442f102da7 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -92,6 +92,7 @@ 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 73336c144d926..d28324a872314 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -297,8 +297,7 @@ 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 fc7867ce90e5e..ac55997bd90e2 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1430,9 +1430,8 @@ 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. */ @@ -1440,8 +1439,8 @@ 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); } @@ -1453,6 +1452,7 @@ 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; }