linux/net/core/dev.h
Sebastian Andrzej Siewior ecefbc09e8 net: softnet_data: Make xmit per task.
Softirq is preemptible on PREEMPT_RT. Without a per-CPU lock in
local_bh_disable() there is no guarantee that only one device is
transmitting at a time.
With preemption and multiple senders it is possible that the per-CPU
`recursion' counter gets incremented by different threads and exceeds
XMIT_RECURSION_LIMIT leading to a false positive recursion alert.
The `more' member is subject to similar problems if set by one thread
for one driver and wrongly used by another driver within another thread.

Instead of adding a lock to protect the per-CPU variable it is simpler
to make xmit per-task. Sending and receiving skbs happens always
in thread context anyway.

Having a lock to protected the per-CPU counter would block/ serialize two
sending threads needlessly. It would also require a recursive lock to
ensure that the owner can increment the counter further.

Make the softnet_data.xmit a task_struct member on PREEMPT_RT. Add
needed wrapper.

Cc: Ben Segall <bsegall@google.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20240620132727.660738-9-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-24 16:41:23 -07:00

192 lines
5.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _NET_CORE_DEV_H
#define _NET_CORE_DEV_H
#include <linux/types.h>
#include <linux/rwsem.h>
#include <linux/netdevice.h>
struct net;
struct netlink_ext_ack;
struct cpumask;
/* Random bits of netdevice that don't need to be exposed */
#define FLOW_LIMIT_HISTORY (1 << 7) /* must be ^2 and !overflow buckets */
struct sd_flow_limit {
u64 count;
unsigned int num_buckets;
unsigned int history_head;
u16 history[FLOW_LIMIT_HISTORY];
u8 buckets[];
};
extern int netdev_flow_limit_table_len;
#ifdef CONFIG_PROC_FS
int __init dev_proc_init(void);
#else
#define dev_proc_init() 0
#endif
void linkwatch_init_dev(struct net_device *dev);
void linkwatch_run_queue(void);
void dev_addr_flush(struct net_device *dev);
int dev_addr_init(struct net_device *dev);
void dev_addr_check(struct net_device *dev);
/* sysctls not referred to from outside net/core/ */
extern int netdev_unregister_timeout_secs;
extern int weight_p;
extern int dev_weight_rx_bias;
extern int dev_weight_tx_bias;
extern struct rw_semaphore dev_addr_sem;
/* rtnl helpers */
extern struct list_head net_todo_list;
void netdev_run_todo(void);
/* netdev management, shared between various uAPI entry points */
struct netdev_name_node {
struct hlist_node hlist;
struct list_head list;
struct net_device *dev;
const char *name;
struct rcu_head rcu;
};
int netdev_get_name(struct net *net, char *name, int ifindex);
int dev_change_name(struct net_device *dev, const char *newname);
#define netdev_for_each_altname(dev, namenode) \
list_for_each_entry((namenode), &(dev)->name_node->list, list)
#define netdev_for_each_altname_safe(dev, namenode, next) \
list_for_each_entry_safe((namenode), (next), &(dev)->name_node->list, \
list)
int netdev_name_node_alt_create(struct net_device *dev, const char *name);
int netdev_name_node_alt_destroy(struct net_device *dev, const char *name);
int dev_validate_mtu(struct net_device *dev, int mtu,
struct netlink_ext_ack *extack);
int dev_set_mtu_ext(struct net_device *dev, int mtu,
struct netlink_ext_ack *extack);
int dev_get_phys_port_id(struct net_device *dev,
struct netdev_phys_item_id *ppid);
int dev_get_phys_port_name(struct net_device *dev,
char *name, size_t len);
int dev_change_proto_down(struct net_device *dev, bool proto_down);
void dev_change_proto_down_reason(struct net_device *dev, unsigned long mask,
u32 value);
typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
int fd, int expected_fd, u32 flags);
int dev_change_tx_queue_len(struct net_device *dev, unsigned long new_len);
void dev_set_group(struct net_device *dev, int new_group);
int dev_change_carrier(struct net_device *dev, bool new_carrier);
void __dev_set_rx_mode(struct net_device *dev);
void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
unsigned int gchanges, u32 portid,
const struct nlmsghdr *nlh);
void unregister_netdevice_many_notify(struct list_head *head,
u32 portid, const struct nlmsghdr *nlh);
static inline void netif_set_gso_max_size(struct net_device *dev,
unsigned int size)
{
/* dev->gso_max_size is read locklessly from sk_setup_caps() */
WRITE_ONCE(dev->gso_max_size, size);
if (size <= GSO_LEGACY_MAX_SIZE)
WRITE_ONCE(dev->gso_ipv4_max_size, size);
}
static inline void netif_set_gso_max_segs(struct net_device *dev,
unsigned int segs)
{
/* dev->gso_max_segs is read locklessly from sk_setup_caps() */
WRITE_ONCE(dev->gso_max_segs, segs);
}
static inline void netif_set_gro_max_size(struct net_device *dev,
unsigned int size)
{
/* This pairs with the READ_ONCE() in skb_gro_receive() */
WRITE_ONCE(dev->gro_max_size, size);
if (size <= GRO_LEGACY_MAX_SIZE)
WRITE_ONCE(dev->gro_ipv4_max_size, size);
}
static inline void netif_set_gso_ipv4_max_size(struct net_device *dev,
unsigned int size)
{
/* dev->gso_ipv4_max_size is read locklessly from sk_setup_caps() */
WRITE_ONCE(dev->gso_ipv4_max_size, size);
}
static inline void netif_set_gro_ipv4_max_size(struct net_device *dev,
unsigned int size)
{
/* This pairs with the READ_ONCE() in skb_gro_receive() */
WRITE_ONCE(dev->gro_ipv4_max_size, size);
}
int rps_cpumask_housekeeping(struct cpumask *mask);
#if defined(CONFIG_DEBUG_NET) && defined(CONFIG_BPF_SYSCALL)
void xdp_do_check_flushed(struct napi_struct *napi);
#else
static inline void xdp_do_check_flushed(struct napi_struct *napi) { }
#endif
struct napi_struct *napi_by_id(unsigned int napi_id);
void kick_defer_list_purge(struct softnet_data *sd, unsigned int cpu);
#define XMIT_RECURSION_LIMIT 8
#ifndef CONFIG_PREEMPT_RT
static inline bool dev_xmit_recursion(void)
{
return unlikely(__this_cpu_read(softnet_data.xmit.recursion) >
XMIT_RECURSION_LIMIT);
}
static inline void dev_xmit_recursion_inc(void)
{
__this_cpu_inc(softnet_data.xmit.recursion);
}
static inline void dev_xmit_recursion_dec(void)
{
__this_cpu_dec(softnet_data.xmit.recursion);
}
#else
static inline bool dev_xmit_recursion(void)
{
return unlikely(current->net_xmit.recursion > XMIT_RECURSION_LIMIT);
}
static inline void dev_xmit_recursion_inc(void)
{
current->net_xmit.recursion++;
}
static inline void dev_xmit_recursion_dec(void)
{
current->net_xmit.recursion--;
}
#endif
int dev_set_hwtstamp_phylib(struct net_device *dev,
struct kernel_hwtstamp_config *cfg,
struct netlink_ext_ack *extack);
#endif