ca99ca14c9
Ivan Vercera was recently backporting commit
9c13cb8bb4 to a RHEL kernel, and I noticed that,
while this patch protects the tg3 driver from having its ndo_poll_controller
routine called during device initalization, it does nothing for the driver
during shutdown. I.e. it would be entirely possible to have the
ndo_poll_controller method (or subsequently the ndo_poll) routine called for a
driver in the netpoll path on CPU A while in parallel on CPU B, the ndo_close or
ndo_open routine could be called. Given that the two latter routines tend to
initizlize and free many data structures that the former two rely on, the result
can easily be data corruption or various other crashes. Furthermore, it seems
that this is potentially a problem with all net drivers that support netpoll,
and so this should ideally be fixed in a common path.
As Ben H Pointed out to me, we can't preform dev_open/dev_close in atomic
context, so I've come up with this solution. We can use a mutex to sleep in
open/close paths and just do a mutex_trylock in the napi poll path and abandon
the poll attempt if we're locked, as we'll just retry the poll on the next send
anyway.
I've tested this here by flooding netconsole with messages on a system whos nic
driver I modfied to periodically return NETDEV_TX_BUSY, so that the netpoll tx
workqueue would be forced to send frames and poll the device. While this was
going on I rapidly ifdown/up'ed the interface and watched for any problems.
I've not found any.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Ivan Vecera <ivecera@redhat.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Ben Hutchings <bhutchings@solarflare.com>
CC: Francois Romieu <romieu@fr.zoreil.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 rcu_head rcu;
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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_rcu(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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