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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH net-next v4] xen-netfront: clean up code in xennet_release_rx_bufs
From: Annie Li <annie.li@xxxxxxxxxx>
This patch removes grant transfer releasing code from netfront, and uses
gnttab_end_foreign_access to end grant access since
gnttab_end_foreign_access_ref may fail when the grant entry is
currently used for reading or writing.
* clean up grant transfer code kept from old netfront(2.6.18) which grants
pages for access/map and transfer. But grant transfer is deprecated in current
netfront, so remove corresponding release code for transfer.
* release grant access (through gnttab_end_foreign_access) and skb for tx/rx
path,
use get_page to ensure page is released when grant access is completed
successfully.
Xen-blkfront/xen-tpmfront/xen-pcifront also have similar issue, but patches
for them will be created separately.
V4: Revert put_page in gnttab_end_foreign_access, and keep netfront change in
single patch
V3: Changes as suggestion from David Vrabel, ensure pages are not freed untill
grant acess is ended.
V2: Improve patch comments.
Signed-off-by: Annie Li <annie.li@xxxxxxxxxx>
---
drivers/net/xen-netfront.c | 93 ++++++++++++++-----------------------------
1 files changed, 30 insertions(+), 63 deletions(-)
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index d7bee8a..a22adaa 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -117,6 +117,7 @@ struct netfront_info {
} tx_skbs[NET_TX_RING_SIZE];
grant_ref_t gref_tx_head;
grant_ref_t grant_tx_ref[NET_TX_RING_SIZE];
+ struct page *grant_tx_page[NET_TX_RING_SIZE];
unsigned tx_skb_freelist;
spinlock_t rx_lock ____cacheline_aligned_in_smp;
@@ -396,6 +397,7 @@ static void xennet_tx_buf_gc(struct net_device *dev)
gnttab_release_grant_reference(
&np->gref_tx_head, np->grant_tx_ref[id]);
np->grant_tx_ref[id] = GRANT_INVALID_REF;
+ np->grant_tx_page[id] = NULL;
add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs,
id);
dev_kfree_skb_irq(skb);
}
@@ -452,6 +454,7 @@ static void xennet_make_frags(struct sk_buff *skb, struct
net_device *dev,
gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
mfn, GNTMAP_readonly);
+ np->grant_tx_page[id] = virt_to_page(data);
tx->gref = np->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = len;
@@ -497,6 +500,7 @@ static void xennet_make_frags(struct sk_buff *skb, struct
net_device *dev,
np->xbdev->otherend_id,
mfn, GNTMAP_readonly);
+ np->grant_tx_page[id] = page;
tx->gref = np->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = bytes;
@@ -596,6 +600,7 @@ static int xennet_start_xmit(struct sk_buff *skb, struct
net_device *dev)
mfn = virt_to_mfn(data);
gnttab_grant_foreign_access_ref(
ref, np->xbdev->otherend_id, mfn, GNTMAP_readonly);
+ np->grant_tx_page[id] = virt_to_page(data);
tx->gref = np->grant_tx_ref[id] = ref;
tx->offset = offset;
tx->size = len;
@@ -1085,10 +1090,11 @@ static void xennet_release_tx_bufs(struct netfront_info
*np)
continue;
skb = np->tx_skbs[i].skb;
- gnttab_end_foreign_access_ref(np->grant_tx_ref[i],
- GNTMAP_readonly);
- gnttab_release_grant_reference(&np->gref_tx_head,
- np->grant_tx_ref[i]);
+ get_page(np->grant_tx_page[i]);
+ gnttab_end_foreign_access(np->grant_tx_ref[i],
+ GNTMAP_readonly,
+ (unsigned
long)page_address(np->grant_tx_page[i]));
+ np->grant_tx_page[i] = NULL;
np->grant_tx_ref[i] = GRANT_INVALID_REF;
add_id_to_freelist(&np->tx_skb_freelist, np->tx_skbs, i);
dev_kfree_skb_irq(skb);
@@ -1097,78 +1103,35 @@ static void xennet_release_tx_bufs(struct netfront_info
*np)
static void xennet_release_rx_bufs(struct netfront_info *np)
{
- struct mmu_update *mmu = np->rx_mmu;
- struct multicall_entry *mcl = np->rx_mcl;
- struct sk_buff_head free_list;
- struct sk_buff *skb;
- unsigned long mfn;
- int xfer = 0, noxfer = 0, unused = 0;
int id, ref;
- dev_warn(&np->netdev->dev, "%s: fix me for copying receiver.\n",
- __func__);
- return;
-
- skb_queue_head_init(&free_list);
-
spin_lock_bh(&np->rx_lock);
for (id = 0; id < NET_RX_RING_SIZE; id++) {
- ref = np->grant_rx_ref[id];
- if (ref == GRANT_INVALID_REF) {
- unused++;
- continue;
- }
+ struct sk_buff *skb;
+ struct page *page;
skb = np->rx_skbs[id];
- mfn = gnttab_end_foreign_transfer_ref(ref);
- gnttab_release_grant_reference(&np->gref_rx_head, ref);
- np->grant_rx_ref[id] = GRANT_INVALID_REF;
-
- if (0 == mfn) {
- skb_shinfo(skb)->nr_frags = 0;
- dev_kfree_skb(skb);
- noxfer++;
+ if (!skb)
continue;
- }
-
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- /* Remap the page. */
- const struct page *page =
- skb_frag_page(&skb_shinfo(skb)->frags[0]);
- unsigned long pfn = page_to_pfn(page);
- void *vaddr = page_address(page);
- MULTI_update_va_mapping(mcl, (unsigned long)vaddr,
- mfn_pte(mfn, PAGE_KERNEL),
- 0);
- mcl++;
- mmu->ptr = ((u64)mfn << PAGE_SHIFT)
- | MMU_MACHPHYS_UPDATE;
- mmu->val = pfn;
- mmu++;
+ ref = np->grant_rx_ref[id];
+ if (ref == GRANT_INVALID_REF)
+ continue;
- set_phys_to_machine(pfn, mfn);
- }
- __skb_queue_tail(&free_list, skb);
- xfer++;
- }
+ page = skb_frag_page(&skb_shinfo(skb)->frags[0]);
- dev_info(&np->netdev->dev, "%s: %d xfer, %d noxfer, %d unused\n",
- __func__, xfer, noxfer, unused);
+ /* gnttab_end_foreign_access() needs a page ref until
+ * foreign access is ended (which may be deferred).
+ */
+ get_page(page);
+ gnttab_end_foreign_access(ref, 0,
+ (unsigned long)page_address(page));
+ np->grant_rx_ref[id] = GRANT_INVALID_REF;
- if (xfer) {
- if (!xen_feature(XENFEAT_auto_translated_physmap)) {
- /* Do all the remapping work and M2P updates. */
- MULTI_mmu_update(mcl, np->rx_mmu, mmu - np->rx_mmu,
- NULL, DOMID_SELF);
- mcl++;
- HYPERVISOR_multicall(np->rx_mcl, mcl - np->rx_mcl);
- }
+ kfree_skb(skb);
}
- __skb_queue_purge(&free_list);
-
spin_unlock_bh(&np->rx_lock);
}
@@ -1339,6 +1302,7 @@ static struct net_device *xennet_create_dev(struct
xenbus_device *dev)
for (i = 0; i < NET_RX_RING_SIZE; i++) {
np->rx_skbs[i] = NULL;
np->grant_rx_ref[i] = GRANT_INVALID_REF;
+ np->grant_tx_page[i] = NULL;
}
/* A grant for every tx ring slot */
@@ -1439,8 +1403,11 @@ static int netfront_probe(struct xenbus_device *dev,
static void xennet_end_access(int ref, void *page)
{
/* This frees the page as a side-effect */
- if (ref != GRANT_INVALID_REF)
+ if (ref != GRANT_INVALID_REF) {
+ get_page(virt_to_page(page));
gnttab_end_foreign_access(ref, 0, (unsigned long)page);
+ free_page((unsigned long)page);
+ }
}
static void xennet_disconnect_backend(struct netfront_info *info)
--
1.7.3.4
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