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alistair23-linux/include/linux/atmdev.h
David Woodhouse 9bbe60a67b atm: Preserve value of skb->truesize when accounting to vcc 
ATM accounts for in-flight TX packets in sk_wmem_alloc of the VCC on
which they are to be sent. But it doesn't take ownership of those
packets from the sock (if any) which originally owned them. They should
remain owned by their actual sender until they've left the box.

There's a hack in pskb_expand_head() to avoid adjusting skb->truesize
for certain skbs, precisely to avoid messing up sk_wmem_alloc
accounting. Ideally that hack would cover the ATM use case too, but it
doesn't — skbs which aren't owned by any sock, for example PPP control
frames, still get their truesize adjusted when the low-level ATM driver
adds headroom.

This has always been an issue, it seems. The truesize of a packet
increases, and sk_wmem_alloc on the VCC goes negative. But this wasn't
for normal traffic, only for control frames. So I think we just got away
with it, and we probably needed to send 2GiB of LCP echo frames before
the misaccounting would ever have caused a problem and caused
atm_may_send() to start refusing packets.

Commit 14afee4b60 ("net: convert sock.sk_wmem_alloc from atomic_t to
refcount_t") did exactly what it was intended to do, and turned this
mostly-theoretical problem into a real one, causing PPPoATM to fail
immediately as sk_wmem_alloc underflows and atm_may_send() *immediately*
starts refusing to allow new packets.

The least intrusive solution to this problem is to stash the value of
skb->truesize that was accounted to the VCC, in a new member of the
ATM_SKB(skb) structure. Then in atm_pop_raw() subtract precisely that
value instead of the then-current value of skb->truesize.

Fixes: 158f323b98 ("net: adjust skb->truesize in pskb_expand_head()")
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Tested-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-17 08:27:01 +09:00

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/* SPDX-License-Identifier: GPL-2.0 */
/* atmdev.h - ATM device driver declarations and various related items */
#ifndef LINUX_ATMDEV_H
#define LINUX_ATMDEV_H
#include <linux/wait.h> /* wait_queue_head_t */
#include <linux/time.h> /* struct timeval */
#include <linux/net.h>
#include <linux/bug.h>
#include <linux/skbuff.h> /* struct sk_buff */
#include <linux/uio.h>
#include <net/sock.h>
#include <linux/atomic.h>
#include <linux/refcount.h>
#include <uapi/linux/atmdev.h>
#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
extern struct proc_dir_entry *atm_proc_root;
#endif
#ifdef CONFIG_COMPAT
#include <linux/compat.h>
struct compat_atm_iobuf {
int length;
compat_uptr_t buffer;
};
#endif
struct k_atm_aal_stats {
#define __HANDLE_ITEM(i) atomic_t i
__AAL_STAT_ITEMS
#undef __HANDLE_ITEM
};
struct k_atm_dev_stats {
struct k_atm_aal_stats aal0;
struct k_atm_aal_stats aal34;
struct k_atm_aal_stats aal5;
};
struct device;
enum {
ATM_VF_ADDR, /* Address is in use. Set by anybody, cleared
by device driver. */
ATM_VF_READY, /* VC is ready to transfer data. Set by device
driver, cleared by anybody. */
ATM_VF_PARTIAL, /* resources are bound to PVC (partial PVC
setup), controlled by socket layer */
ATM_VF_REGIS, /* registered with demon, controlled by SVC
socket layer */
ATM_VF_BOUND, /* local SAP is set, controlled by SVC socket
layer */
ATM_VF_RELEASED, /* demon has indicated/requested release,
controlled by SVC socket layer */
ATM_VF_HASQOS, /* QOS parameters have been set */
ATM_VF_LISTEN, /* socket is used for listening */
ATM_VF_META, /* SVC socket isn't used for normal data
traffic and doesn't depend on signaling
to be available */
ATM_VF_SESSION, /* VCC is p2mp session control descriptor */
ATM_VF_HASSAP, /* SAP has been set */
ATM_VF_CLOSE, /* asynchronous close - treat like VF_RELEASED*/
ATM_VF_WAITING, /* waiting for reply from sigd */
ATM_VF_IS_CLIP, /* in use by CLIP protocol */
};
#define ATM_VF2VS(flags) \
(test_bit(ATM_VF_READY,&(flags)) ? ATM_VS_CONNECTED : \
test_bit(ATM_VF_RELEASED,&(flags)) ? ATM_VS_CLOSING : \
test_bit(ATM_VF_LISTEN,&(flags)) ? ATM_VS_LISTEN : \
test_bit(ATM_VF_REGIS,&(flags)) ? ATM_VS_INUSE : \
test_bit(ATM_VF_BOUND,&(flags)) ? ATM_VS_BOUND : ATM_VS_IDLE)
enum {
ATM_DF_REMOVED, /* device was removed from atm_devs list */
};
#define ATM_PHY_SIG_LOST 0 /* no carrier/light */
#define ATM_PHY_SIG_UNKNOWN 1 /* carrier/light status is unknown */
#define ATM_PHY_SIG_FOUND 2 /* carrier/light okay */
#define ATM_ATMOPT_CLP 1 /* set CLP bit */
struct atm_vcc {
/* struct sock has to be the first member of atm_vcc */
struct sock sk;
unsigned long flags; /* VCC flags (ATM_VF_*) */
short vpi; /* VPI and VCI (types must be equal */
/* with sockaddr) */
int vci;
unsigned long aal_options; /* AAL layer options */
unsigned long atm_options; /* ATM layer options */
struct atm_dev *dev; /* device back pointer */
struct atm_qos qos; /* QOS */
struct atm_sap sap; /* SAP */
void (*release_cb)(struct atm_vcc *vcc); /* release_sock callback */
void (*push)(struct atm_vcc *vcc,struct sk_buff *skb);
void (*pop)(struct atm_vcc *vcc,struct sk_buff *skb); /* optional */
int (*push_oam)(struct atm_vcc *vcc,void *cell);
int (*send)(struct atm_vcc *vcc,struct sk_buff *skb);
void *dev_data; /* per-device data */
void *proto_data; /* per-protocol data */
struct k_atm_aal_stats *stats; /* pointer to AAL stats group */
struct module *owner; /* owner of ->push function */
/* SVC part --- may move later ------------------------------------- */
short itf; /* interface number */
struct sockaddr_atmsvc local;
struct sockaddr_atmsvc remote;
/* Multipoint part ------------------------------------------------- */
struct atm_vcc *session; /* session VCC descriptor */
/* Other stuff ----------------------------------------------------- */
void *user_back; /* user backlink - not touched by */
/* native ATM stack. Currently used */
/* by CLIP and sch_atm. */
};
static inline struct atm_vcc *atm_sk(struct sock *sk)
{
return (struct atm_vcc *)sk;
}
static inline struct atm_vcc *ATM_SD(struct socket *sock)
{
return atm_sk(sock->sk);
}
static inline struct sock *sk_atm(struct atm_vcc *vcc)
{
return (struct sock *)vcc;
}
struct atm_dev_addr {
struct sockaddr_atmsvc addr; /* ATM address */
struct list_head entry; /* next address */
};
enum atm_addr_type_t { ATM_ADDR_LOCAL, ATM_ADDR_LECS };
struct atm_dev {
const struct atmdev_ops *ops; /* device operations; NULL if unused */
const struct atmphy_ops *phy; /* PHY operations, may be undefined */
/* (NULL) */
const char *type; /* device type name */
int number; /* device index */
void *dev_data; /* per-device data */
void *phy_data; /* private PHY date */
unsigned long flags; /* device flags (ATM_DF_*) */
struct list_head local; /* local ATM addresses */
struct list_head lecs; /* LECS ATM addresses learned via ILMI */
unsigned char esi[ESI_LEN]; /* ESI ("MAC" addr) */
struct atm_cirange ci_range; /* VPI/VCI range */
struct k_atm_dev_stats stats; /* statistics */
char signal; /* signal status (ATM_PHY_SIG_*) */
int link_rate; /* link rate (default: OC3) */
refcount_t refcnt; /* reference count */
spinlock_t lock; /* protect internal members */
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *proc_entry; /* proc entry */
char *proc_name; /* proc entry name */
#endif
struct device class_dev; /* sysfs device */
struct list_head dev_list; /* linkage */
};
/* OF: send_Oam Flags */
#define ATM_OF_IMMED 1 /* Attempt immediate delivery */
#define ATM_OF_INRATE 2 /* Attempt in-rate delivery */
/*
* ioctl, getsockopt, and setsockopt are optional and can be set to NULL.
*/
struct atmdev_ops { /* only send is required */
void (*dev_close)(struct atm_dev *dev);
int (*open)(struct atm_vcc *vcc);
void (*close)(struct atm_vcc *vcc);
int (*ioctl)(struct atm_dev *dev,unsigned int cmd,void __user *arg);
#ifdef CONFIG_COMPAT
int (*compat_ioctl)(struct atm_dev *dev,unsigned int cmd,
void __user *arg);
#endif
int (*getsockopt)(struct atm_vcc *vcc,int level,int optname,
void __user *optval,int optlen);
int (*setsockopt)(struct atm_vcc *vcc,int level,int optname,
void __user *optval,unsigned int optlen);
int (*send)(struct atm_vcc *vcc,struct sk_buff *skb);
int (*send_oam)(struct atm_vcc *vcc,void *cell,int flags);
void (*phy_put)(struct atm_dev *dev,unsigned char value,
unsigned long addr);
unsigned char (*phy_get)(struct atm_dev *dev,unsigned long addr);
int (*change_qos)(struct atm_vcc *vcc,struct atm_qos *qos,int flags);
int (*proc_read)(struct atm_dev *dev,loff_t *pos,char *page);
struct module *owner;
};
struct atmphy_ops {
int (*start)(struct atm_dev *dev);
int (*ioctl)(struct atm_dev *dev,unsigned int cmd,void __user *arg);
void (*interrupt)(struct atm_dev *dev);
int (*stop)(struct atm_dev *dev);
};
struct atm_skb_data {
struct atm_vcc *vcc; /* ATM VCC */
unsigned long atm_options; /* ATM layer options */
unsigned int acct_truesize; /* truesize accounted to vcc */
};
#define VCC_HTABLE_SIZE 32
extern struct hlist_head vcc_hash[VCC_HTABLE_SIZE];
extern rwlock_t vcc_sklist_lock;
#define ATM_SKB(skb) (((struct atm_skb_data *) (skb)->cb))
struct atm_dev *atm_dev_register(const char *type, struct device *parent,
const struct atmdev_ops *ops,
int number, /* -1 == pick first available */
unsigned long *flags);
struct atm_dev *atm_dev_lookup(int number);
void atm_dev_deregister(struct atm_dev *dev);
/* atm_dev_signal_change
*
* Propagate lower layer signal change in atm_dev->signal to netdevice.
* The event will be sent via a notifier call chain.
*/
void atm_dev_signal_change(struct atm_dev *dev, char signal);
void vcc_insert_socket(struct sock *sk);
void atm_dev_release_vccs(struct atm_dev *dev);
static inline void atm_account_tx(struct atm_vcc *vcc, struct sk_buff *skb)
{
/*
* Because ATM skbs may not belong to a sock (and we don't
* necessarily want to), skb->truesize may be adjusted,
* escaping the hack in pskb_expand_head() which avoids
* doing so for some cases. So stash the value of truesize
* at the time we accounted it, and atm_pop_raw() can use
* that value later, in case it changes.
*/
refcount_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
ATM_SKB(skb)->acct_truesize = skb->truesize;
ATM_SKB(skb)->atm_options = vcc->atm_options;
}
static inline void atm_force_charge(struct atm_vcc *vcc,int truesize)
{
atomic_add(truesize, &sk_atm(vcc)->sk_rmem_alloc);
}
static inline void atm_return(struct atm_vcc *vcc,int truesize)
{
atomic_sub(truesize, &sk_atm(vcc)->sk_rmem_alloc);
}
static inline int atm_may_send(struct atm_vcc *vcc,unsigned int size)
{
return (size + refcount_read(&sk_atm(vcc)->sk_wmem_alloc)) <
sk_atm(vcc)->sk_sndbuf;
}
static inline void atm_dev_hold(struct atm_dev *dev)
{
refcount_inc(&dev->refcnt);
}
static inline void atm_dev_put(struct atm_dev *dev)
{
if (refcount_dec_and_test(&dev->refcnt)) {
BUG_ON(!test_bit(ATM_DF_REMOVED, &dev->flags));
if (dev->ops->dev_close)
dev->ops->dev_close(dev);
put_device(&dev->class_dev);
}
}
int atm_charge(struct atm_vcc *vcc,int truesize);
struct sk_buff *atm_alloc_charge(struct atm_vcc *vcc,int pdu_size,
gfp_t gfp_flags);
int atm_pcr_goal(const struct atm_trafprm *tp);
void vcc_release_async(struct atm_vcc *vcc, int reply);
struct atm_ioctl {
struct module *owner;
/* A module reference is kept if appropriate over this call.
* Return -ENOIOCTLCMD if you don't handle it. */
int (*ioctl)(struct socket *, unsigned int cmd, unsigned long arg);
struct list_head list;
};
/**
* register_atm_ioctl - register handler for ioctl operations
*
* Special (non-device) handlers of ioctl's should
* register here. If you're a normal device, you should
* set .ioctl in your atmdev_ops instead.
*/
void register_atm_ioctl(struct atm_ioctl *);
/**
* deregister_atm_ioctl - remove the ioctl handler
*/
void deregister_atm_ioctl(struct atm_ioctl *);
/* register_atmdevice_notifier - register atm_dev notify events
*
* Clients like br2684 will register notify events
* Currently we notify of signal found/lost
*/
int register_atmdevice_notifier(struct notifier_block *nb);
void unregister_atmdevice_notifier(struct notifier_block *nb);
#endif
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