lkml.org 
[lkml]   [2012]   [Jan]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] add netconsole support for xen-netfront
    On Tue, Jan 17, 2012 at 01:42:22PM -0800, Tina Yang wrote:
    > On 1/13/2012 3:06 AM, Ian Campbell wrote:
    > >On Thu, 2012-01-12 at 14:17 +0000, Konrad Rzeszutek Wilk wrote:
    > >>On Wed, Jan 11, 2012 at 04:52:36PM +0800, Zhenzhong Duan wrote:
    > >>>add polling interface to xen-netfront device to support netconsole
    > >>>
    > >>Ian, any thoughts on the spinlock changes?
    > >What are they for?
    > When I did this patch back in 2008, both netconsole and netdump
    > were supported. Spin_lock w/o irqsave and irqrestore would cause
    > netdump hang due to the unexpected change of the irq status.

    Hm, that might have been due to the bug that was lurking in there since
    2.6.27: d198d499148a0c64a41b3aba9e7dd43772832b91 "xen: x86_32: do not enable iterrupts when returning from exception in interrupt context"

    > Although netdump is now obsolete, I think it's always a good practice
    > to preserve caller's irq status as we had a very bad experience
    > chasing a similar problem caused by such a irq change in RDS

    Did you find the culprit of it? Was there a patch for that in the
    upstream kernel?

    > in the not too long ago past.

    OK, it sounds like it was issues in the past but might not be the
    case anymore.

    Could please re-test it without that spinlock irqsave patch using
    the upstream kernel (or just UEK2 since it is an 3.0 type kernel).

    Thanks.

    > >At a guess they are a necessary consequence of the new calling context.
    > >However not all the drivers I looked at which supported netpool were
    > >using the irqsave variants in this context so I guess it must be some
    > >secondary effect.
    > >
    > >Anyway, the upshot is that I think the changelog needs to explain the
    > >rationale for the locking change.
    > >
    > >Ian.
    > >
    > >>>Signed-off-by: Tina.Yang<tina.yang@oracle.com>
    > >>>Cc: Konrad Rzeszutek Wilk<konrad.wilk@oracle.com>
    > >>>Cc: Jeremy Fitzhardinge<jeremy@goop.org>
    > >>>Signed-off-by: Zhenzhong.Duan<zhenzhong.duan@oracle.com>
    > >>>Tested-by: gurudas.pai<gurudas.pai@oracle.com>
    > >>>---
    > >>> drivers/net/xen-netfront.c | 57 ++++++++++++++++++++++++++-----------------
    > >>> 1 files changed, 34 insertions(+), 23 deletions(-)
    > >>>
    > >>>diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
    > >>>index fa67905..db638b4 100644
    > >>>--- a/drivers/net/xen-netfront.c
    > >>>+++ b/drivers/net/xen-netfront.c
    > >>>@@ -489,6 +489,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
    > >>> int frags = skb_shinfo(skb)->nr_frags;
    > >>> unsigned int offset = offset_in_page(data);
    > >>> unsigned int len = skb_headlen(skb);
    > >>>+ unsigned long flags;
    > >>>
    > >>> frags += DIV_ROUND_UP(offset + len, PAGE_SIZE);
    > >>> if (unlikely(frags> MAX_SKB_FRAGS + 1)) {
    > >>>@@ -498,12 +499,12 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
    > >>> goto drop;
    > >>> }
    > >>>
    > >>>- spin_lock_irq(&np->tx_lock);
    > >>>+ spin_lock_irqsave(&np->tx_lock, flags);
    > >>>
    > >>> if (unlikely(!netif_carrier_ok(dev) ||
    > >>> (frags> 1&& !xennet_can_sg(dev)) ||
    > >>> netif_needs_gso(skb, netif_skb_features(skb)))) {
    > >>>- spin_unlock_irq(&np->tx_lock);
    > >>>+ spin_unlock_irqrestore(&np->tx_lock, flags);
    > >>> goto drop;
    > >>> }
    > >>>
    > >>>@@ -574,7 +575,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
    > >>> if (!netfront_tx_slot_available(np))
    > >>> netif_stop_queue(dev);
    > >>>
    > >>>- spin_unlock_irq(&np->tx_lock);
    > >>>+ spin_unlock_irqrestore(&np->tx_lock, flags);
    > >>>
    > >>> return NETDEV_TX_OK;
    > >>>
    > >>>@@ -1228,6 +1229,33 @@ static int xennet_set_features(struct net_device *dev,
    > >>> return 0;
    > >>> }
    > >>>
    > >>>+static irqreturn_t xennet_interrupt(int irq, void *dev_id)
    > >>>+{
    > >>>+ struct net_device *dev = dev_id;
    > >>>+ struct netfront_info *np = netdev_priv(dev);
    > >>>+ unsigned long flags;
    > >>>+
    > >>>+ spin_lock_irqsave(&np->tx_lock, flags);
    > >>>+
    > >>>+ if (likely(netif_carrier_ok(dev))) {
    > >>>+ xennet_tx_buf_gc(dev);
    > >>>+ /* Under tx_lock: protects access to rx shared-ring indexes. */
    > >>>+ if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
    > >>>+ napi_schedule(&np->napi);
    > >>>+ }
    > >>>+
    > >>>+ spin_unlock_irqrestore(&np->tx_lock, flags);
    > >>>+
    > >>>+ return IRQ_HANDLED;
    > >>>+}
    > >>>+
    > >>>+#ifdef CONFIG_NET_POLL_CONTROLLER
    > >>>+static void xennet_poll_controller(struct net_device *dev)
    > >>>+{
    > >>>+ xennet_interrupt(0, dev);
    > >>>+}
    > >>>+#endif
    > >>>+
    > >>> static const struct net_device_ops xennet_netdev_ops = {
    > >>> .ndo_open = xennet_open,
    > >>> .ndo_uninit = xennet_uninit,
    > >>>@@ -1239,6 +1267,9 @@ static const struct net_device_ops xennet_netdev_ops = {
    > >>> .ndo_validate_addr = eth_validate_addr,
    > >>> .ndo_fix_features = xennet_fix_features,
    > >>> .ndo_set_features = xennet_set_features,
    > >>>+#ifdef CONFIG_NET_POLL_CONTROLLER
    > >>>+ .ndo_poll_controller = xennet_poll_controller,
    > >>>+#endif
    > >>> };
    > >>>
    > >>> static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev)
    > >>>@@ -1448,26 +1479,6 @@ static int xen_net_read_mac(struct xenbus_device *dev, u8 mac[])
    > >>> return 0;
    > >>> }
    > >>>
    > >>>-static irqreturn_t xennet_interrupt(int irq, void *dev_id)
    > >>>-{
    > >>>- struct net_device *dev = dev_id;
    > >>>- struct netfront_info *np = netdev_priv(dev);
    > >>>- unsigned long flags;
    > >>>-
    > >>>- spin_lock_irqsave(&np->tx_lock, flags);
    > >>>-
    > >>>- if (likely(netif_carrier_ok(dev))) {
    > >>>- xennet_tx_buf_gc(dev);
    > >>>- /* Under tx_lock: protects access to rx shared-ring indexes. */
    > >>>- if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
    > >>>- napi_schedule(&np->napi);
    > >>>- }
    > >>>-
    > >>>- spin_unlock_irqrestore(&np->tx_lock, flags);
    > >>>-
    > >>>- return IRQ_HANDLED;
    > >>>-}
    > >>>-
    > >>> static int setup_netfront(struct xenbus_device *dev, struct netfront_info *info)
    > >>> {
    > >>> struct xen_netif_tx_sring *txs;
    > >>>--
    > >>>1.7.3
    > >


    \
     
     \ /
      Last update: 2012-01-17 22:55    [W:0.039 / U:1.184 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site