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xen-netback: avoid allocating variable size array on stack 

Tune xen_netbk_count_requests to not touch working array beyond limit, so that
we can make working array size constant.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Liu 2013-05-02 00:43:58 +00:00 committed by David S. Miller
parent ac69c26e7a
commit 59ccb4ebbc
1 changed files with 14 additions and 2 deletions
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16
drivers/net/xen-netback/netback.c
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@ -934,11 +934,14 @@ static int netbk_count_requests(struct xenvif *vif,
RING_IDX cons = vif->tx.req_cons;
int slots = 0;
int drop_err = 0;
int more_data;
if (!(first->flags & XEN_NETTXF_more_data))
return 0;
do {
struct xen_netif_tx_request dropped_tx = { 0 };
if (slots >= work_to_do) {
netdev_err(vif->dev,
"Asked for %d slots but exceeds this limit\n",
@ -972,6 +975,9 @@ static int netbk_count_requests(struct xenvif *vif,
drop_err = -E2BIG;
}
if (drop_err)
txp = &dropped_tx;
memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
sizeof(*txp));
@ -1001,7 +1007,13 @@ static int netbk_count_requests(struct xenvif *vif,
netbk_fatal_tx_err(vif);
return -EINVAL;
}
} while ((txp++)->flags & XEN_NETTXF_more_data);
more_data = txp->flags & XEN_NETTXF_more_data;
if (!drop_err)
txp++;
} while (more_data);
if (drop_err) {
netbk_tx_err(vif, first, cons + slots);
@ -1408,7 +1420,7 @@ static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
!list_empty(&netbk->net_schedule_list)) {
struct xenvif *vif;
struct xen_netif_tx_request txreq;
struct xen_netif_tx_request txfrags[max_skb_slots];
struct xen_netif_tx_request txfrags[XEN_NETIF_NR_SLOTS_MIN];
struct page *page;
struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
u16 pending_idx;