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ipvs: separate destination availability state

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IPVS configuration paths update destination availability while connection
accounting updates destination overload state. The two independent states
share dest->flags, so their read-modify-write updates can race and lose one
another.

Keep OVERLOAD in flags, where the preceding patch serializes its updates
with dst_lock, and move AVAILABLE to cflags. This keeps configuration-
controlled availability out of the scheduler hot cacheline until a
scheduler needs to check it. It also prevents availability updates from
clobbering overload state.

The destination status bits are not exposed through the IPVS sockopt or
netlink interfaces, so keep their definitions in the internal IPVS header.

Readers can still observe stale destination state; this does not provide a
cross-field snapshot.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
Reported-by: Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn>
Reported-by: Ao Wang <wangao@seu.edu.cn>
Reported-by: Xuewei Feng <fengxw06@126.com>
Reported-by: Qi Li <qli01@tsinghua.edu.cn>
Reported-by: Ke Xu <xuke@tsinghua.edu.cn>
Link: https://lore.kernel.org/all/8913381c-1e02-35c7-0ec4-61de5a12fd35@ssi.bg/
Assisted-by: Claude-Code:GLM-5.2
Suggested-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Yizhou Zhao
2026-07-31 22:27:43 +08:00
committed by Pablo Neira Ayuso
parent 8f843441c4
commit cdcc4e4618
9 changed files with 23 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
include/net/ip_vs.h
View File

@@ -36,6 +36,12 @@
#define IP_VS_HDR_INVERSE 1
#define IP_VS_HDR_ICMP 2
/* Destination Server Flags */
#define IP_VS_DEST_F_OVERLOAD 0x0002 /* server is overloaded */
/* Destination Server Config Flags */
#define IP_VS_DEST_CF_AVAILABLE 0x0001 /* server is available */
/* conn_tab limits (as per Kconfig) */
#define IP_VS_CONN_TAB_MIN_BITS 8
#if BITS_PER_LONG > 32
@@ -976,6 +982,7 @@ struct ip_vs_dest {
volatile unsigned int flags; /* dest status flags */
atomic_t conn_flags; /* flags to copy to conn */
atomic_t weight; /* server weight */
unsigned long cflags; /* config flags */
atomic_t last_weight; /* server latest weight */
__u16 tun_type; /* tunnel type */
__be16 tun_port; /* tunnel port */

6
include/uapi/linux/ip_vs.h
View File

@@ -28,12 +28,6 @@
#define IP_VS_SVC_F_SCHED_SH_FALLBACK IP_VS_SVC_F_SCHED1 /* SH fallback */
#define IP_VS_SVC_F_SCHED_SH_PORT IP_VS_SVC_F_SCHED2 /* SH use port */
/*
* Destination Server Flags
*/
#define IP_VS_DEST_F_AVAILABLE 0x0001 /* server is available */
#define IP_VS_DEST_F_OVERLOAD 0x0002 /* server is overloaded */
/*
* IPVS sync daemon states
*/

4
net/netfilter/ipvs/ip_vs_conn.c
View File

@@ -1279,7 +1279,7 @@ int ip_vs_check_template(struct ip_vs_conn *ct, struct ip_vs_dest *cdest)
* Checking the dest server status.
*/
if ((dest == NULL) ||
!(dest->flags & IP_VS_DEST_F_AVAILABLE) ||
!(dest->cflags & IP_VS_DEST_CF_AVAILABLE) ||
expire_quiescent_template(ipvs, dest) ||
(cdest && (dest != cdest))) {
IP_VS_DBG_BUF(9, "check_template: dest not available for "
@@ -2020,7 +2020,7 @@ void ip_vs_expire_nodest_conn_flush(struct netns_ipvs *ipvs)
cp = ip_vs_hn0_to_conn(hn);
resched_score++;
dest = cp->dest;
if (!dest || (dest->flags & IP_VS_DEST_F_AVAILABLE))
if (!dest || (dest->cflags & IP_VS_DEST_CF_AVAILABLE))
continue;
if (atomic_read(&cp->n_control))

6
net/netfilter/ipvs/ip_vs_core.c
View File

@@ -302,7 +302,7 @@ ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
struct ip_vs_dest *dest = cp->dest;
struct netns_ipvs *ipvs = cp->ipvs;
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
if (dest && (dest->cflags & IP_VS_DEST_CF_AVAILABLE)) {
struct ip_vs_cpu_stats *s;
struct ip_vs_service *svc;
@@ -338,7 +338,7 @@ ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb)
struct ip_vs_dest *dest = cp->dest;
struct netns_ipvs *ipvs = cp->ipvs;
if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
if (dest && (dest->cflags & IP_VS_DEST_CF_AVAILABLE)) {
struct ip_vs_cpu_stats *s;
struct ip_vs_service *svc;
@@ -2210,7 +2210,7 @@ ip_vs_in_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *state
}
/* Check the server status */
if (cp && cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) {
if (cp && cp->dest && !(cp->dest->cflags & IP_VS_DEST_CF_AVAILABLE)) {
/* the destination server is not available */
if (sysctl_expire_nodest_conn(ipvs)) {
bool old_ct = ip_vs_conn_uses_old_conntrack(cp, skb);

4
net/netfilter/ipvs/ip_vs_ctl.c
View File

@@ -1402,7 +1402,7 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
}
/* set the dest status flags */
dest->flags |= IP_VS_DEST_F_AVAILABLE;
dest->cflags |= IP_VS_DEST_CF_AVAILABLE;
if (READ_ONCE(dest->u_threshold) != udest->u_threshold ||
READ_ONCE(dest->l_threshold) != udest->l_threshold) {
@@ -1662,7 +1662,7 @@ static void __ip_vs_unlink_dest(struct ip_vs_service *svc,
struct ip_vs_dest *dest,
int svcupd)
{
dest->flags &= ~IP_VS_DEST_F_AVAILABLE;
dest->cflags &= ~IP_VS_DEST_CF_AVAILABLE;
spin_lock_bh(&dest->dst_lock);
__ip_vs_dst_cache_reset(dest);

4
net/netfilter/ipvs/ip_vs_dh.c
View File

@@ -219,8 +219,8 @@ ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
s = (struct ip_vs_dh_state *) svc->sched_data;
dest = ip_vs_dh_get(svc->af, s, &iph->daddr);
if (!dest
|| !(dest->flags & IP_VS_DEST_F_AVAILABLE)
if (!dest ||
!(dest->cflags & IP_VS_DEST_CF_AVAILABLE)
|| atomic_read(&dest->weight) <= 0
|| is_overloaded(dest)) {
ip_vs_scheduler_err(svc, "no destination available");

2
net/netfilter/ipvs/ip_vs_lblc.c
View File

@@ -502,7 +502,7 @@ ip_vs_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
*/
dest = en->dest;
if ((dest->flags & IP_VS_DEST_F_AVAILABLE) &&
if ((dest->cflags & IP_VS_DEST_CF_AVAILABLE) &&
atomic_read(&dest->weight) > 0 && !is_overloaded(dest, svc))
goto out;
}

8
net/netfilter/ipvs/ip_vs_lblcr.c
View File

@@ -169,8 +169,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
if (least->flags & IP_VS_DEST_F_OVERLOAD)
continue;
if ((atomic_read(&least->weight) > 0)
&& (least->flags & IP_VS_DEST_F_AVAILABLE)) {
if ((atomic_read(&least->weight) > 0) &&
(least->cflags & IP_VS_DEST_CF_AVAILABLE)) {
loh = ip_vs_dest_conn_overhead(least);
goto nextstage;
}
@@ -186,8 +186,8 @@ static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
doh = ip_vs_dest_conn_overhead(dest);
if (((__s64)loh * atomic_read(&dest->weight) >
(__s64)doh * atomic_read(&least->weight))
&& (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
(__s64)doh * atomic_read(&least->weight)) &&
(dest->cflags & IP_VS_DEST_CF_AVAILABLE)) {
least = dest;
loh = doh;
}

4
net/netfilter/ipvs/ip_vs_xmit.c
View File

@@ -351,7 +351,7 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
* stored in dest_trash.
*/
if (!rt_dev_is_down(dst_dev_rcu(&rt->dst)) &&
dest->flags & IP_VS_DEST_F_AVAILABLE)
dest->cflags & IP_VS_DEST_CF_AVAILABLE)
__ip_vs_dst_set(dest, dest_dst, &rt->dst, 0);
else
noref = 0;
@@ -530,7 +530,7 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
* stored in dest_trash.
*/
if (!rt_dev_is_down(dst_dev_rcu(&rt->dst)) &&
dest->flags & IP_VS_DEST_F_AVAILABLE)
dest->cflags & IP_VS_DEST_CF_AVAILABLE)
__ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
else
noref = 0;