2cde6acd49
__netpoll_rcu_free is used to free netpoll structures when the rtnl_lock is already held. The mechanism is used to asynchronously call __netpoll_cleanup outside of the holding of the rtnl_lock, so as to avoid deadlock. Unfortunately, __netpoll_cleanup modifies pointers (dev->np), which means the rtnl_lock must be held while calling it. Further, it cannot be held, because rcu callbacks may be issued in softirq contexts, which cannot sleep. Fix this by converting the rcu callback to a work queue that is guaranteed to get scheduled in process context, so that we can hold the rtnl properly while calling __netpoll_cleanup Tested successfully by myself. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> CC: "David S. Miller" <davem@davemloft.net> CC: Cong Wang <amwang@redhat.com> CC: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
181 lines
4 KiB
C
181 lines
4 KiB
C
/*
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* Common code for low-level network console, dump, and debugger code
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*
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* Derived from netconsole, kgdb-over-ethernet, and netdump patches
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*/
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#ifndef _LINUX_NETPOLL_H
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#define _LINUX_NETPOLL_H
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#include <linux/netdevice.h>
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#include <linux/interrupt.h>
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#include <linux/rcupdate.h>
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#include <linux/list.h>
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union inet_addr {
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__u32 all[4];
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__be32 ip;
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__be32 ip6[4];
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struct in_addr in;
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struct in6_addr in6;
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};
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struct netpoll {
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struct net_device *dev;
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char dev_name[IFNAMSIZ];
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const char *name;
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void (*rx_hook)(struct netpoll *, int, char *, int);
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union inet_addr local_ip, remote_ip;
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bool ipv6;
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u16 local_port, remote_port;
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u8 remote_mac[ETH_ALEN];
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struct list_head rx; /* rx_np list element */
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struct work_struct cleanup_work;
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};
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struct netpoll_info {
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atomic_t refcnt;
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unsigned long rx_flags;
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spinlock_t rx_lock;
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struct mutex dev_lock;
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struct list_head rx_np; /* netpolls that registered an rx_hook */
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struct sk_buff_head neigh_tx; /* list of neigh requests to reply to */
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struct sk_buff_head txq;
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struct delayed_work tx_work;
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struct netpoll *netpoll;
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struct rcu_head rcu;
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};
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#ifdef CONFIG_NETPOLL
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extern int netpoll_rx_disable(struct net_device *dev);
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extern void netpoll_rx_enable(struct net_device *dev);
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#else
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static inline int netpoll_rx_disable(struct net_device *dev) { return 0; }
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static inline void netpoll_rx_enable(struct net_device *dev) { return; }
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#endif
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void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
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void netpoll_print_options(struct netpoll *np);
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int netpoll_parse_options(struct netpoll *np, char *opt);
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int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp);
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int netpoll_setup(struct netpoll *np);
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int netpoll_trap(void);
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void netpoll_set_trap(int trap);
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void __netpoll_cleanup(struct netpoll *np);
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void __netpoll_free_async(struct netpoll *np);
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void netpoll_cleanup(struct netpoll *np);
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int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo);
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void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
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struct net_device *dev);
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static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
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{
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unsigned long flags;
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local_irq_save(flags);
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netpoll_send_skb_on_dev(np, skb, np->dev);
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local_irq_restore(flags);
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}
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#ifdef CONFIG_NETPOLL
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static inline bool netpoll_rx_on(struct sk_buff *skb)
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{
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struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo);
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return npinfo && (!list_empty(&npinfo->rx_np) || npinfo->rx_flags);
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}
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static inline bool netpoll_rx(struct sk_buff *skb)
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{
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struct netpoll_info *npinfo;
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unsigned long flags;
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bool ret = false;
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local_irq_save(flags);
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if (!netpoll_rx_on(skb))
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goto out;
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npinfo = rcu_dereference_bh(skb->dev->npinfo);
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spin_lock(&npinfo->rx_lock);
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/* check rx_flags again with the lock held */
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if (npinfo->rx_flags && __netpoll_rx(skb, npinfo))
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ret = true;
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spin_unlock(&npinfo->rx_lock);
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out:
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local_irq_restore(flags);
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return ret;
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}
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static inline int netpoll_receive_skb(struct sk_buff *skb)
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{
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if (!list_empty(&skb->dev->napi_list))
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return netpoll_rx(skb);
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return 0;
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}
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static inline void *netpoll_poll_lock(struct napi_struct *napi)
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{
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struct net_device *dev = napi->dev;
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if (dev && dev->npinfo) {
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spin_lock(&napi->poll_lock);
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napi->poll_owner = smp_processor_id();
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return napi;
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}
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return NULL;
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}
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static inline void netpoll_poll_unlock(void *have)
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{
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struct napi_struct *napi = have;
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if (napi) {
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napi->poll_owner = -1;
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spin_unlock(&napi->poll_lock);
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}
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}
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static inline bool netpoll_tx_running(struct net_device *dev)
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{
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return irqs_disabled();
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}
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#else
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static inline bool netpoll_rx(struct sk_buff *skb)
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{
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return false;
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}
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static inline bool netpoll_rx_on(struct sk_buff *skb)
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{
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return false;
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}
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static inline int netpoll_receive_skb(struct sk_buff *skb)
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{
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return 0;
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}
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static inline void *netpoll_poll_lock(struct napi_struct *napi)
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{
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return NULL;
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}
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static inline void netpoll_poll_unlock(void *have)
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{
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}
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static inline void netpoll_netdev_init(struct net_device *dev)
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{
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}
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static inline bool netpoll_tx_running(struct net_device *dev)
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{
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return false;
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}
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#endif
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#endif
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