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linux/include/net/dst.h
Eric Dumazet 6c1c509778 net: add atomic_long_t to net_device_stats fields 
Long standing KCSAN issues are caused by data-race around
some dev->stats changes.

Most performance critical paths already use per-cpu
variables, or per-queue ones.

It is reasonable (and more correct) to use atomic operations
for the slow paths.

This patch adds an union for each field of net_device_stats,
so that we can convert paths that are not yet protected
by a spinlock or a mutex.

netdev_stats_to_stats64() no longer has an #if BITS_PER_LONG==64

Note that the memcpy() we were using on 64bit arches
had no provision to avoid load-tearing,
while atomic_long_read() is providing the needed protection
at no cost.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-11-16 12:48:44 +00:00

561 lines
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/* SPDX-License-Identifier: GPL-2.0 */
/*
* net/dst.h Protocol independent destination cache definitions.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*
*/
#ifndef _NET_DST_H
#define _NET_DST_H
#include <net/dst_ops.h>
#include <linux/netdevice.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
#include <linux/bug.h>
#include <linux/jiffies.h>
#include <linux/refcount.h>
#include <net/neighbour.h>
#include <asm/processor.h>
#include <linux/indirect_call_wrapper.h>
struct sk_buff;
struct dst_entry {
struct net_device *dev;
struct dst_ops *ops;
unsigned long _metrics;
unsigned long expires;
#ifdef CONFIG_XFRM
struct xfrm_state *xfrm;
#else
void *__pad1;
#endif
int (*input)(struct sk_buff *);
int (*output)(struct net *net, struct sock *sk, struct sk_buff *skb);
unsigned short flags;
#define DST_NOXFRM 0x0002
#define DST_NOPOLICY 0x0004
#define DST_NOCOUNT 0x0008
#define DST_FAKE_RTABLE 0x0010
#define DST_XFRM_TUNNEL 0x0020
#define DST_XFRM_QUEUE 0x0040
#define DST_METADATA 0x0080
/* A non-zero value of dst->obsolete forces by-hand validation
* of the route entry. Positive values are set by the generic
* dst layer to indicate that the entry has been forcefully
* destroyed.
*
* Negative values are used by the implementation layer code to
* force invocation of the dst_ops->check() method.
*/
short obsolete;
#define DST_OBSOLETE_NONE 0
#define DST_OBSOLETE_DEAD 2
#define DST_OBSOLETE_FORCE_CHK -1
#define DST_OBSOLETE_KILL -2
unsigned short header_len; /* more space at head required */
unsigned short trailer_len; /* space to reserve at tail */
/*
* __refcnt wants to be on a different cache line from
* input/output/ops or performance tanks badly
*/
#ifdef CONFIG_64BIT
atomic_t __refcnt; /* 64-bit offset 64 */
#endif
int __use;
unsigned long lastuse;
struct lwtunnel_state *lwtstate;
struct rcu_head rcu_head;
short error;
short __pad;
__u32 tclassid;
#ifndef CONFIG_64BIT
atomic_t __refcnt; /* 32-bit offset 64 */
#endif
netdevice_tracker dev_tracker;
};
struct dst_metrics {
u32 metrics[RTAX_MAX];
refcount_t refcnt;
} __aligned(4); /* Low pointer bits contain DST_METRICS_FLAGS */
extern const struct dst_metrics dst_default_metrics;
u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
#define DST_METRICS_READ_ONLY 0x1UL
#define DST_METRICS_REFCOUNTED 0x2UL
#define DST_METRICS_FLAGS 0x3UL
#define __DST_METRICS_PTR(Y) \
((u32 *)((Y) & ~DST_METRICS_FLAGS))
#define DST_METRICS_PTR(X) __DST_METRICS_PTR((X)->_metrics)
static inline bool dst_metrics_read_only(const struct dst_entry *dst)
{
return dst->_metrics & DST_METRICS_READ_ONLY;
}
void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
{
unsigned long val = dst->_metrics;
if (!(val & DST_METRICS_READ_ONLY))
__dst_destroy_metrics_generic(dst, val);
}
static inline u32 *dst_metrics_write_ptr(struct dst_entry *dst)
{
unsigned long p = dst->_metrics;
BUG_ON(!p);
if (p & DST_METRICS_READ_ONLY)
return dst->ops->cow_metrics(dst, p);
return __DST_METRICS_PTR(p);
}
/* This may only be invoked before the entry has reached global
* visibility.
*/
static inline void dst_init_metrics(struct dst_entry *dst,
const u32 *src_metrics,
bool read_only)
{
dst->_metrics = ((unsigned long) src_metrics) |
(read_only ? DST_METRICS_READ_ONLY : 0);
}
static inline void dst_copy_metrics(struct dst_entry *dest, const struct dst_entry *src)
{
u32 *dst_metrics = dst_metrics_write_ptr(dest);
if (dst_metrics) {
u32 *src_metrics = DST_METRICS_PTR(src);
memcpy(dst_metrics, src_metrics, RTAX_MAX * sizeof(u32));
}
}
static inline u32 *dst_metrics_ptr(struct dst_entry *dst)
{
return DST_METRICS_PTR(dst);
}
static inline u32
dst_metric_raw(const struct dst_entry *dst, const int metric)
{
u32 *p = DST_METRICS_PTR(dst);
return p[metric-1];
}
static inline u32
dst_metric(const struct dst_entry *dst, const int metric)
{
WARN_ON_ONCE(metric == RTAX_HOPLIMIT ||
metric == RTAX_ADVMSS ||
metric == RTAX_MTU);
return dst_metric_raw(dst, metric);
}
static inline u32
dst_metric_advmss(const struct dst_entry *dst)
{
u32 advmss = dst_metric_raw(dst, RTAX_ADVMSS);
if (!advmss)
advmss = dst->ops->default_advmss(dst);
return advmss;
}
static inline void dst_metric_set(struct dst_entry *dst, int metric, u32 val)
{
u32 *p = dst_metrics_write_ptr(dst);
if (p)
p[metric-1] = val;
}
/* Kernel-internal feature bits that are unallocated in user space. */
#define DST_FEATURE_ECN_CA (1U << 31)
#define DST_FEATURE_MASK (DST_FEATURE_ECN_CA)
#define DST_FEATURE_ECN_MASK (DST_FEATURE_ECN_CA | RTAX_FEATURE_ECN)
static inline u32
dst_feature(const struct dst_entry *dst, u32 feature)
{
return dst_metric(dst, RTAX_FEATURES) & feature;
}
INDIRECT_CALLABLE_DECLARE(unsigned int ip6_mtu(const struct dst_entry *));
INDIRECT_CALLABLE_DECLARE(unsigned int ipv4_mtu(const struct dst_entry *));
static inline u32 dst_mtu(const struct dst_entry *dst)
{
return INDIRECT_CALL_INET(dst->ops->mtu, ip6_mtu, ipv4_mtu, dst);
}
/* RTT metrics are stored in milliseconds for user ABI, but used as jiffies */
static inline unsigned long dst_metric_rtt(const struct dst_entry *dst, int metric)
{
return msecs_to_jiffies(dst_metric(dst, metric));
}
static inline u32
dst_allfrag(const struct dst_entry *dst)
{
int ret = dst_feature(dst, RTAX_FEATURE_ALLFRAG);
return ret;
}
static inline int
dst_metric_locked(const struct dst_entry *dst, int metric)
{
return dst_metric(dst, RTAX_LOCK) & (1 << metric);
}
static inline void dst_hold(struct dst_entry *dst)
{
/*
* If your kernel compilation stops here, please check
* the placement of __refcnt in struct dst_entry
*/
BUILD_BUG_ON(offsetof(struct dst_entry, __refcnt) & 63);
WARN_ON(atomic_inc_not_zero(&dst->__refcnt) == 0);
}
static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
{
if (unlikely(time != dst->lastuse)) {
dst->__use++;
dst->lastuse = time;
}
}
static inline struct dst_entry *dst_clone(struct dst_entry *dst)
{
if (dst)
dst_hold(dst);
return dst;
}
void dst_release(struct dst_entry *dst);
void dst_release_immediate(struct dst_entry *dst);
static inline void refdst_drop(unsigned long refdst)
{
if (!(refdst & SKB_DST_NOREF))
dst_release((struct dst_entry *)(refdst & SKB_DST_PTRMASK));
}
/**
* skb_dst_drop - drops skb dst
* @skb: buffer
*
* Drops dst reference count if a reference was taken.
*/
static inline void skb_dst_drop(struct sk_buff *skb)
{
if (skb->_skb_refdst) {
refdst_drop(skb->_skb_refdst);
skb->_skb_refdst = 0UL;
}
}
static inline void __skb_dst_copy(struct sk_buff *nskb, unsigned long refdst)
{
nskb->slow_gro |= !!refdst;
nskb->_skb_refdst = refdst;
if (!(nskb->_skb_refdst & SKB_DST_NOREF))
dst_clone(skb_dst(nskb));
}
static inline void skb_dst_copy(struct sk_buff *nskb, const struct sk_buff *oskb)
{
__skb_dst_copy(nskb, oskb->_skb_refdst);
}
/**
* dst_hold_safe - Take a reference on a dst if possible
* @dst: pointer to dst entry
*
* This helper returns false if it could not safely
* take a reference on a dst.
*/
static inline bool dst_hold_safe(struct dst_entry *dst)
{
return atomic_inc_not_zero(&dst->__refcnt);
}
/**
* skb_dst_force - makes sure skb dst is refcounted
* @skb: buffer
*
* If dst is not yet refcounted and not destroyed, grab a ref on it.
* Returns true if dst is refcounted.
*/
static inline bool skb_dst_force(struct sk_buff *skb)
{
if (skb_dst_is_noref(skb)) {
struct dst_entry *dst = skb_dst(skb);
WARN_ON(!rcu_read_lock_held());
if (!dst_hold_safe(dst))
dst = NULL;
skb->_skb_refdst = (unsigned long)dst;
skb->slow_gro |= !!dst;
}
return skb->_skb_refdst != 0UL;
}
/**
* __skb_tunnel_rx - prepare skb for rx reinsert
* @skb: buffer
* @dev: tunnel device
* @net: netns for packet i/o
*
* After decapsulation, packet is going to re-enter (netif_rx()) our stack,
* so make some cleanups. (no accounting done)
*/
static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
struct net *net)
{
skb->dev = dev;
/*
* Clear hash so that we can recalulate the hash for the
* encapsulated packet, unless we have already determine the hash
* over the L4 4-tuple.
*/
skb_clear_hash_if_not_l4(skb);
skb_set_queue_mapping(skb, 0);
skb_scrub_packet(skb, !net_eq(net, dev_net(dev)));
}
/**
* skb_tunnel_rx - prepare skb for rx reinsert
* @skb: buffer
* @dev: tunnel device
* @net: netns for packet i/o
*
* After decapsulation, packet is going to re-enter (netif_rx()) our stack,
* so make some cleanups, and perform accounting.
* Note: this accounting is not SMP safe.
*/
static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev,
struct net *net)
{
DEV_STATS_INC(dev, rx_packets);
DEV_STATS_ADD(dev, rx_bytes, skb->len);
__skb_tunnel_rx(skb, dev, net);
}
static inline u32 dst_tclassid(const struct sk_buff *skb)
{
#ifdef CONFIG_IP_ROUTE_CLASSID
const struct dst_entry *dst;
dst = skb_dst(skb);
if (dst)
return dst->tclassid;
#endif
return 0;
}
int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb);
static inline int dst_discard(struct sk_buff *skb)
{
return dst_discard_out(&init_net, skb->sk, skb);
}
void *dst_alloc(struct dst_ops *ops, struct net_device *dev, int initial_ref,
int initial_obsolete, unsigned short flags);
void dst_init(struct dst_entry *dst, struct dst_ops *ops,
struct net_device *dev, int initial_ref, int initial_obsolete,
unsigned short flags);
struct dst_entry *dst_destroy(struct dst_entry *dst);
void dst_dev_put(struct dst_entry *dst);
static inline void dst_confirm(struct dst_entry *dst)
{
}
static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
{
struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
return IS_ERR(n) ? NULL : n;
}
static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
struct sk_buff *skb)
{
struct neighbour *n;
if (WARN_ON_ONCE(!dst->ops->neigh_lookup))
return NULL;
n = dst->ops->neigh_lookup(dst, skb, NULL);
return IS_ERR(n) ? NULL : n;
}
static inline void dst_confirm_neigh(const struct dst_entry *dst,
const void *daddr)
{
if (dst->ops->confirm_neigh)
dst->ops->confirm_neigh(dst, daddr);
}
static inline void dst_link_failure(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
if (dst && dst->ops && dst->ops->link_failure)
dst->ops->link_failure(skb);
}
static inline void dst_set_expires(struct dst_entry *dst, int timeout)
{
unsigned long expires = jiffies + timeout;
if (expires == 0)
expires = 1;
if (dst->expires == 0 || time_before(expires, dst->expires))
dst->expires = expires;
}
INDIRECT_CALLABLE_DECLARE(int ip6_output(struct net *, struct sock *,
struct sk_buff *));
INDIRECT_CALLABLE_DECLARE(int ip_output(struct net *, struct sock *,
struct sk_buff *));
/* Output packet to network from transport. */
static inline int dst_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
return INDIRECT_CALL_INET(skb_dst(skb)->output,
ip6_output, ip_output,
net, sk, skb);
}
INDIRECT_CALLABLE_DECLARE(int ip6_input(struct sk_buff *));
INDIRECT_CALLABLE_DECLARE(int ip_local_deliver(struct sk_buff *));
/* Input packet from network to transport. */
static inline int dst_input(struct sk_buff *skb)
{
return INDIRECT_CALL_INET(skb_dst(skb)->input,
ip6_input, ip_local_deliver, skb);
}
INDIRECT_CALLABLE_DECLARE(struct dst_entry *ip6_dst_check(struct dst_entry *,
u32));
INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
u32));
static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie)
{
if (dst->obsolete)
dst = INDIRECT_CALL_INET(dst->ops->check, ip6_dst_check,
ipv4_dst_check, dst, cookie);
return dst;
}
/* Flags for xfrm_lookup flags argument. */
enum {
XFRM_LOOKUP_ICMP = 1 << 0,
XFRM_LOOKUP_QUEUE = 1 << 1,
XFRM_LOOKUP_KEEP_DST_REF = 1 << 2,
};
struct flowi;
#ifndef CONFIG_XFRM
static inline struct dst_entry *xfrm_lookup(struct net *net,
struct dst_entry *dst_orig,
const struct flowi *fl,
const struct sock *sk,
int flags)
{
return dst_orig;
}
static inline struct dst_entry *
xfrm_lookup_with_ifid(struct net *net, struct dst_entry *dst_orig,
const struct flowi *fl, const struct sock *sk,
int flags, u32 if_id)
{
return dst_orig;
}
static inline struct dst_entry *xfrm_lookup_route(struct net *net,
struct dst_entry *dst_orig,
const struct flowi *fl,
const struct sock *sk,
int flags)
{
return dst_orig;
}
static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
{
return NULL;
}
#else
struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
const struct flowi *fl, const struct sock *sk,
int flags);
struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
struct dst_entry *dst_orig,
const struct flowi *fl,
const struct sock *sk, int flags,
u32 if_id);
struct dst_entry *xfrm_lookup_route(struct net *net, struct dst_entry *dst_orig,
const struct flowi *fl, const struct sock *sk,
int flags);
/* skb attached with this dst needs transformation if dst->xfrm is valid */
static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst)
{
return dst->xfrm;
}
#endif
static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu)
{
struct dst_entry *dst = skb_dst(skb);
if (dst && dst->ops->update_pmtu)
dst->ops->update_pmtu(dst, NULL, skb, mtu, true);
}
/* update dst pmtu but not do neighbor confirm */
static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu)
{
struct dst_entry *dst = skb_dst(skb);
if (dst && dst->ops->update_pmtu)
dst->ops->update_pmtu(dst, NULL, skb, mtu, false);
}
struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie);
void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb, u32 mtu, bool confirm_neigh);
void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
struct sk_buff *skb);
u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old);
struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst,
struct sk_buff *skb,
const void *daddr);
unsigned int dst_blackhole_mtu(const struct dst_entry *dst);
#endif /* _NET_DST_H */
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