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Date: Tue, 07 Jan 2014 20:29:51 -0500 (EST)
From: David Miller <davem@...emloft.net>
To: zoltan.kiss@...rix.com
Cc: ian.campbell@...rix.com, wei.liu2@...rix.com,
xen-devel@...ts.xenproject.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, jonathan.davies@...rix.com
Subject: Re: [PATCH net-next v3 1/9] xen-netback: Introduce TX grant map
definitions
From: Zoltan Kiss <zoltan.kiss@...rix.com>
Date: Wed, 8 Jan 2014 00:10:10 +0000
> This patch contains the new definitions necessary for grant mapping.
>
> v2:
> - move unmapping to separate thread. The NAPI instance has to be scheduled
> even from thread context, which can cause huge delays
> - that causes unfortunately bigger struct xenvif
> - store grant handle after checking validity
>
> v3:
> - fix comment in xenvif_tx_dealloc_action()
> - call unmap hypercall directly instead of gnttab_unmap_refs(), which does
> unnecessary m2p_override. Also remove pages_to_[un]map members
> - BUG() if grant_tx_handle corrupted
>
> Signed-off-by: Zoltan Kiss <zoltan.kiss@...rix.com>
>
> ---
> drivers/net/xen-netback/common.h | 25 ++++++
> drivers/net/xen-netback/interface.c | 1 +
> drivers/net/xen-netback/netback.c | 163 +++++++++++++++++++++++++++++++++++
> 3 files changed, 189 insertions(+)
>
> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
> index d218ccd..f1071e3 100644
> --- a/drivers/net/xen-netback/common.h
> +++ b/drivers/net/xen-netback/common.h
> @@ -79,6 +79,11 @@ struct pending_tx_info {
> * if it is head of one or more tx
> * reqs
> */
> + /* callback data for released SKBs. The callback is always
> + * xenvif_zerocopy_callback, ctx points to the next fragment, desc
> + * contains the pending_idx
> + */
> + struct ubuf_info callback_struct;
> };
>
> #define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, PAGE_SIZE)
> @@ -108,6 +113,8 @@ struct xenvif_rx_meta {
> */
> #define MAX_GRANT_COPY_OPS (MAX_SKB_FRAGS * XEN_NETIF_RX_RING_SIZE)
>
> +#define NETBACK_INVALID_HANDLE -1
> +
> struct xenvif {
> /* Unique identifier for this interface. */
> domid_t domid;
> @@ -126,13 +133,23 @@ struct xenvif {
> pending_ring_idx_t pending_cons;
> u16 pending_ring[MAX_PENDING_REQS];
> struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
> + grant_handle_t grant_tx_handle[MAX_PENDING_REQS];
>
> /* Coalescing tx requests before copying makes number of grant
> * copy ops greater or equal to number of slots required. In
> * worst case a tx request consumes 2 gnttab_copy.
> */
> struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
> + struct gnttab_map_grant_ref tx_map_ops[MAX_PENDING_REQS];
> + struct gnttab_unmap_grant_ref tx_unmap_ops[MAX_PENDING_REQS];
>
> + spinlock_t dealloc_lock;
> + spinlock_t response_lock;
> + pending_ring_idx_t dealloc_prod;
> + pending_ring_idx_t dealloc_cons;
> + u16 dealloc_ring[MAX_PENDING_REQS];
> + struct task_struct *dealloc_task;
> + wait_queue_head_t dealloc_wq;
>
> /* Use kthread for guest RX */
> struct task_struct *task;
> @@ -221,6 +238,8 @@ int xenvif_tx_action(struct xenvif *vif, int budget);
> int xenvif_kthread(void *data);
> void xenvif_kick_thread(struct xenvif *vif);
>
> +int xenvif_dealloc_kthread(void *data);
> +
> /* Determine whether the needed number of slots (req) are available,
> * and set req_event if not.
> */
> @@ -228,6 +247,12 @@ bool xenvif_rx_ring_slots_available(struct xenvif *vif, int needed);
>
> void xenvif_stop_queue(struct xenvif *vif);
>
> +/* Callback from stack when TX packet can be released */
> +void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success);
> +
> +/* Unmap a pending page, usually has to be called before xenvif_idx_release */
> +void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx);
> +
> extern bool separate_tx_rx_irq;
>
> #endif /* __XEN_NETBACK__COMMON_H__ */
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 8d6def2..7170f97 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -37,6 +37,7 @@
>
> #include <xen/events.h>
> #include <asm/xen/hypercall.h>
> +#include <xen/balloon.h>
>
> #define XENVIF_QUEUE_LENGTH 32
> #define XENVIF_NAPI_WEIGHT 64
> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index addfe1d1..7c241f9 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -771,6 +771,19 @@ static struct page *xenvif_alloc_page(struct xenvif *vif,
> return page;
> }
>
> +static inline void xenvif_tx_create_gop(struct xenvif *vif, u16 pending_idx,
> + struct xen_netif_tx_request *txp,
> + struct gnttab_map_grant_ref *gop)
> +{
> + gnttab_set_map_op(gop, idx_to_kaddr(vif, pending_idx),
> + GNTMAP_host_map | GNTMAP_readonly,
> + txp->gref, vif->domid);
> +
> + memcpy(&vif->pending_tx_info[pending_idx].req, txp,
> + sizeof(*txp));
> +
> +}
> +
> static struct gnttab_copy *xenvif_get_requests(struct xenvif *vif,
> struct sk_buff *skb,
> struct xen_netif_tx_request *txp,
> @@ -1599,6 +1612,105 @@ static int xenvif_tx_submit(struct xenvif *vif)
> return work_done;
> }
>
> +void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
> +{
> + unsigned long flags;
> + pending_ring_idx_t index;
> + u16 pending_idx = ubuf->desc;
> + struct pending_tx_info *temp =
> + container_of(ubuf, struct pending_tx_info, callback_struct);
> + struct xenvif *vif =
> + container_of(temp - pending_idx, struct xenvif,
> + pending_tx_info[0]);
> +
> + spin_lock_irqsave(&vif->dealloc_lock, flags);
> + do {
> + pending_idx = ubuf->desc;
> + ubuf = (struct ubuf_info *) ubuf->ctx;
> + index = pending_index(vif->dealloc_prod);
> + vif->dealloc_ring[index] = pending_idx;
> + /* Sync with xenvif_tx_action_dealloc:
> + * insert idx then incr producer.
> + */
> + smp_wmb();
> + vif->dealloc_prod++;
> + } while (ubuf);
> + wake_up(&vif->dealloc_wq);
> + spin_unlock_irqrestore(&vif->dealloc_lock, flags);
> +}
> +
> +static inline void xenvif_tx_dealloc_action(struct xenvif *vif)
> +{
> + struct gnttab_unmap_grant_ref *gop;
> + pending_ring_idx_t dc, dp;
> + u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
> + unsigned int i = 0;
> +
> + dc = vif->dealloc_cons;
> + gop = vif->tx_unmap_ops;
> +
> + /* Free up any grants we have finished using */
> + do {
> + dp = vif->dealloc_prod;
> +
> + /* Ensure we see all indices enqueued by all
> + * xenvif_zerocopy_callback().
> + */
> + smp_rmb();
> +
> + while (dc != dp) {
> + pending_idx =
> + vif->dealloc_ring[pending_index(dc++)];
> +
> + /* Already unmapped? */
> + if (vif->grant_tx_handle[pending_idx] ==
> + NETBACK_INVALID_HANDLE) {
> + netdev_err(vif->dev,
> + "Trying to unmap invalid handle! "
> + "pending_idx: %x\n", pending_idx);
> + continue;
> + }
> +
> + pending_idx_release[gop-vif->tx_unmap_ops] =
> + pending_idx;
> + gnttab_set_unmap_op(gop,
> + idx_to_kaddr(vif, pending_idx),
> + GNTMAP_host_map,
> + vif->grant_tx_handle[pending_idx]);
> + vif->grant_tx_handle[pending_idx] =
> + NETBACK_INVALID_HANDLE;
> + ++gop;
> + }
> +
> + } while (dp != vif->dealloc_prod);
> +
> + vif->dealloc_cons = dc;
> +
> + if (gop - vif->tx_unmap_ops > 0) {
> + int ret;
> + ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
> + vif->tx_unmap_ops,
> + gop - vif->tx_unmap_ops);
> + if (ret) {
> + netdev_err(vif->dev, "Unmap fail: nr_ops %x ret %d\n",
> + gop - vif->tx_unmap_ops, ret);
> + for (i = 0; i < gop - vif->tx_unmap_ops; ++i) {
> + netdev_err(vif->dev,
> + " host_addr: %llx handle: %x status: %d\n",
> + gop[i].host_addr,
> + gop[i].handle,
> + gop[i].status);
> + }
> + BUG();
> + }
> + }
> +
> + for (i = 0; i < gop - vif->tx_unmap_ops; ++i)
> + xenvif_idx_release(vif, pending_idx_release[i],
> + XEN_NETIF_RSP_OKAY);
> +}
> +
> +
> /* Called after netfront has transmitted */
> int xenvif_tx_action(struct xenvif *vif, int budget)
> {
> @@ -1665,6 +1777,27 @@ static void xenvif_idx_release(struct xenvif *vif, u16 pending_idx,
> vif->mmap_pages[pending_idx] = NULL;
> }
>
> +void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
> +{
> + int ret;
> + struct gnttab_unmap_grant_ref tx_unmap_op;
> +
> + if (vif->grant_tx_handle[pending_idx] == NETBACK_INVALID_HANDLE) {
> + netdev_err(vif->dev,
> + "Trying to unmap invalid handle! pending_idx: %x\n",
> + pending_idx);
> + return;
> + }
> + gnttab_set_unmap_op(&tx_unmap_op,
> + idx_to_kaddr(vif, pending_idx),
> + GNTMAP_host_map,
> + vif->grant_tx_handle[pending_idx]);
> + ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
> + &tx_unmap_op,
> + 1);
> + BUG_ON(ret);
> + vif->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
> +}
>
> static void make_tx_response(struct xenvif *vif,
> struct xen_netif_tx_request *txp,
> @@ -1726,6 +1859,14 @@ static inline int tx_work_todo(struct xenvif *vif)
> return 0;
> }
>
> +static inline int tx_dealloc_work_todo(struct xenvif *vif)
Make this return bool.
> + return 1;
return true;
> + return 0;
return false;
> + wait_event_interruptible(vif->dealloc_wq,
> + tx_dealloc_work_todo(vif) ||
> + kthread_should_stop());
Inconsistent indentation. You should make the arguments line up at
exactly the first column after the openning parenthesis of the function
call.
--
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