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ipvs: fix overflow on dest weight multiply
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Schedulers such as lblc and lblcr require the weight to be as high as the
maximum number of active connections. In commit b552f7e
("ipvs: unify the formula to estimate the overhead of processing
connections"), the consideration of inactconns and activeconns was cleaned
up to always count activeconns as 256 times more important than inactconns.
In cases where 3000 or more connections are expected, a weight of 3000 *
256 * 3000 connections overflows the 32-bit signed result used to determine
if rescheduling is required.

On amd64, this merely changes the multiply and comparison instructions to
64-bit. On x86, a 64-bit result is already present from imull, so only
a few more comparison instructions are emitted.

Signed-off-by: Simon Kirby <sim@hostway.ca>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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Simon Kirby authored and Simon Horman committed Sep 18, 2013
1 parent 61c5923 commit c16526a
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Showing 6 changed files with 20 additions and 20 deletions.
2 changes: 1 addition & 1 deletion include/net/ip_vs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1649,7 +1649,7 @@ static inline void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
/* CONFIG_IP_VS_NFCT */
#endif

static inline unsigned int
static inline int
ip_vs_dest_conn_overhead(struct ip_vs_dest *dest)
{
/*
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4 changes: 2 additions & 2 deletions net/netfilter/ipvs/ip_vs_lblc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -443,8 +443,8 @@ __ip_vs_lblc_schedule(struct ip_vs_service *svc)
continue;

doh = ip_vs_dest_conn_overhead(dest);
if (loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight)) {
if ((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight)) {
least = dest;
loh = doh;
}
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12 changes: 6 additions & 6 deletions net/netfilter/ipvs/ip_vs_lblcr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -200,8 +200,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
continue;

doh = ip_vs_dest_conn_overhead(dest);
if ((loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight))
if (((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight))
&& (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
least = dest;
loh = doh;
Expand Down Expand Up @@ -246,8 +246,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
dest = rcu_dereference_protected(e->dest, 1);
doh = ip_vs_dest_conn_overhead(dest);
/* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
if ((moh * atomic_read(&dest->weight) <
doh * atomic_read(&most->weight))
if (((__s64)moh * atomic_read(&dest->weight) <
(__s64)doh * atomic_read(&most->weight))
&& (atomic_read(&dest->weight) > 0)) {
most = dest;
moh = doh;
Expand Down Expand Up @@ -611,8 +611,8 @@ __ip_vs_lblcr_schedule(struct ip_vs_service *svc)
continue;

doh = ip_vs_dest_conn_overhead(dest);
if (loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight)) {
if ((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight)) {
least = dest;
loh = doh;
}
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8 changes: 4 additions & 4 deletions net/netfilter/ipvs/ip_vs_nq.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@
#include <net/ip_vs.h>


static inline unsigned int
static inline int
ip_vs_nq_dest_overhead(struct ip_vs_dest *dest)
{
/*
Expand All @@ -59,7 +59,7 @@ ip_vs_nq_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
struct ip_vs_iphdr *iph)
{
struct ip_vs_dest *dest, *least = NULL;
unsigned int loh = 0, doh;
int loh = 0, doh;

IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);

Expand Down Expand Up @@ -92,8 +92,8 @@ ip_vs_nq_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
}

if (!least ||
(loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight))) {
((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight))) {
least = dest;
loh = doh;
}
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8 changes: 4 additions & 4 deletions net/netfilter/ipvs/ip_vs_sed.c
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@
#include <net/ip_vs.h>


static inline unsigned int
static inline int
ip_vs_sed_dest_overhead(struct ip_vs_dest *dest)
{
/*
Expand All @@ -63,7 +63,7 @@ ip_vs_sed_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
struct ip_vs_iphdr *iph)
{
struct ip_vs_dest *dest, *least;
unsigned int loh, doh;
int loh, doh;

IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);

Expand Down Expand Up @@ -99,8 +99,8 @@ ip_vs_sed_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
doh = ip_vs_sed_dest_overhead(dest);
if (loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight)) {
if ((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight)) {
least = dest;
loh = doh;
}
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6 changes: 3 additions & 3 deletions net/netfilter/ipvs/ip_vs_wlc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
struct ip_vs_iphdr *iph)
{
struct ip_vs_dest *dest, *least;
unsigned int loh, doh;
int loh, doh;

IP_VS_DBG(6, "ip_vs_wlc_schedule(): Scheduling...\n");

Expand Down Expand Up @@ -71,8 +71,8 @@ ip_vs_wlc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
doh = ip_vs_dest_conn_overhead(dest);
if (loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight)) {
if ((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight)) {
least = dest;
loh = doh;
}
Expand Down

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