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Message-ID: <1395394872.27358.11.camel@kazak.uk.xensource.com>
Date: Fri, 21 Mar 2014 09:41:12 +0000
From: Ian Campbell <Ian.Campbell@...rix.com>
To: Zoltan Kiss <zoltan.kiss@...rix.com>
CC: <wei.liu2@...rix.com>, <xen-devel@...ts.xenproject.org>,
<paul.durrant@...rix.com>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <jonathan.davies@...rix.com>
Subject: Re: [PATCH net-next] xen-netback: Follow-up patch for grant mapping
series
On Thu, 2014-03-20 at 19:32 +0000, Zoltan Kiss wrote:
> Ian made some late comments about the grant mapping series, I incorporated the
> outcomes into this patch. Additional comments, refactoring etc.
I don't know how davem feels about merging these kinds of thing into one
patch but from my point of view the least thing to do is to enumerate
the cleanups -- so that people can verify that the patch does infact do
exactly what it says it does, no more, no less.
> Signed-off-by: Zoltan Kiss <zoltan.kiss@...rix.com>
> ---
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 6837bfc..fa19538 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -576,15 +576,15 @@ void xenvif_disconnect(struct xenvif *vif)
> void xenvif_free(struct xenvif *vif)
> {
> int i, unmap_timeout = 0;
> - /* Here we want to avoid timeout messages if an skb can be legitimatly
> - * stucked somewhere else. Realisticly this could be an another vif's
> + /* Here we want to avoid timeout messages if an skb can be legitimately
> + * stuck somewhere else. Realistically this could be an another vif's
> * internal or QDisc queue. That another vif also has this
> * rx_drain_timeout_msecs timeout, but the timer only ditches the
> * internal queue. After that, the QDisc queue can put in worst case
> * XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS skbs into that another vif's
> * internal queue, so we need several rounds of such timeouts until we
> * can be sure that no another vif should have skb's from us. We are
> - * not sending more skb's, so newly stucked packets are not interesting
> + * not sending more skb's, so newly stuck packets are not interesting
> * for us here.
> */
> unsigned int worst_case_skb_lifetime = (rx_drain_timeout_msecs/1000) *
> @@ -599,6 +599,13 @@ void xenvif_free(struct xenvif *vif)
> netdev_err(vif->dev,
> "Page still granted! Index: %x\n",
> i);
> + /* If there are still unmapped pages, reset the loop to
> + * start mchecking again. We shouldn't exit here until
"checking"
> + * dealloc thread and NAPI instance release all the
> + * pages. If a kernel bug cause the skbs stall
"causes the skbs to stall"
> + * somewhere, the interface couldn't be brought down
> + * properly.
I'm not sure what you are saying here exactly. Perhaps you means
s/couldn't/cannot/?
> + */
> i = -1;
> }
> }
> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index 1c336f6..0e46184b 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -56,7 +56,7 @@ bool separate_tx_rx_irq = 1;
> module_param(separate_tx_rx_irq, bool, 0644);
>
> /* When guest ring is filled up, qdisc queues the packets for us, but we have
> - * to timeout them, otherwise other guests' packets can get stucked there
> + * to timeout them, otherwise other guests' packets can get stuck there
> */
> unsigned int rx_drain_timeout_msecs = 10000;
> module_param(rx_drain_timeout_msecs, uint, 0444);
> @@ -99,6 +99,9 @@ static inline unsigned long idx_to_kaddr(struct xenvif *vif,
> return (unsigned long)pfn_to_kaddr(idx_to_pfn(vif, idx));
> }
>
> +#define callback_param(vif, pending_idx) \
> + (vif->pending_tx_info[pending_idx].callback_struct)
> +
> /* Find the containing VIF's structure from a pointer in pending_tx_info array
> */
> static inline struct xenvif* ubuf_to_vif(struct ubuf_info *ubuf)
> @@ -1025,12 +1028,12 @@ static void xenvif_fill_frags(struct xenvif *vif, struct sk_buff *skb)
> /* If this is not the first frag, chain it to the previous*/
> if (unlikely(prev_pending_idx == INVALID_PENDING_IDX))
> skb_shinfo(skb)->destructor_arg =
> - &vif->pending_tx_info[pending_idx].callback_struct;
> + &callback_param(vif, pending_idx);
> else if (likely(pending_idx != prev_pending_idx))
> - vif->pending_tx_info[prev_pending_idx].callback_struct.ctx =
> - &(vif->pending_tx_info[pending_idx].callback_struct);
> + callback_param(vif, prev_pending_idx).ctx =
> + &callback_param(vif, pending_idx);
>
> - vif->pending_tx_info[pending_idx].callback_struct.ctx = NULL;
> + callback_param(vif, pending_idx).ctx = NULL;
> prev_pending_idx = pending_idx;
>
> txp = &vif->pending_tx_info[pending_idx].req;
> @@ -1400,13 +1403,13 @@ static int xenvif_tx_submit(struct xenvif *vif)
> memcpy(skb->data,
> (void *)(idx_to_kaddr(vif, pending_idx)|txp->offset),
> data_len);
> - vif->pending_tx_info[pending_idx].callback_struct.ctx = NULL;
> + callback_param(vif, pending_idx).ctx = NULL;
> if (data_len < txp->size) {
> /* Append the packet payload as a fragment. */
> txp->offset += data_len;
> txp->size -= data_len;
> skb_shinfo(skb)->destructor_arg =
> - &vif->pending_tx_info[pending_idx].callback_struct;
> + &callback_param(vif, pending_idx);
> } else {
> /* Schedule a response immediately. */
> xenvif_idx_unmap(vif, pending_idx);
> @@ -1550,7 +1553,6 @@ static inline void xenvif_tx_dealloc_action(struct xenvif *vif)
> idx_to_kaddr(vif, pending_idx),
> GNTMAP_host_map,
> vif->grant_tx_handle[pending_idx]);
> - /* Btw. already unmapped? */
> xenvif_grant_handle_reset(vif, pending_idx);
> ++gop;
> }
> @@ -1683,12 +1685,20 @@ void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
> idx_to_kaddr(vif, pending_idx),
> GNTMAP_host_map,
> vif->grant_tx_handle[pending_idx]);
> - /* Btw. already unmapped? */
> xenvif_grant_handle_reset(vif, pending_idx);
>
> ret = gnttab_unmap_refs(&tx_unmap_op, NULL,
> &vif->mmap_pages[pending_idx], 1);
> - BUG_ON(ret);
> + if (ret) {
> + netdev_err(vif->dev,
> + "Unmap fail: ret: %d pending_idx: %d host_addr: %llx handle: %x status: %d\n",
> + ret,
> + pending_idx,
> + tx_unmap_op.host_addr,
> + tx_unmap_op.handle,
> + tx_unmap_op.status);
> + BUG();
> + }
>
> xenvif_idx_release(vif, pending_idx, XEN_NETIF_RSP_OKAY);
> }
--
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