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author | Florian Zumbiehl <florz@florz.de> | 2007-04-20 16:57:27 -0700 |
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committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:29:19 -0700 |
commit | 74b885cf86def9bc836772e3c1788c00b72a35c9 (patch) | |
tree | 2397bcd487363cdda290c71856af59f0e6cf2ffe /drivers/net/pppoe.c | |
parent | bfafb26e11849fe99e03cc1902a91f7f65354e47 (diff) | |
download | linux-stable-74b885cf86def9bc836772e3c1788c00b72a35c9.tar.gz linux-stable-74b885cf86def9bc836772e3c1788c00b72a35c9.tar.bz2 linux-stable-74b885cf86def9bc836772e3c1788c00b72a35c9.zip |
[PPPOE]: race between interface going down and connect()
below you find a patch that (hopefully) fixes a race between an interface
going down and a connect() to a peer on that interface. Before,
connect() would determine that an interface is up, then the interface
could go down and all entries referring to that interface in the
item_hash_table would be marked as ZOMBIEs and their references to
the device would be freed, and after that, connect() would put a new
entry into the hash table referring to the device that meanwhile is
down already - which also would cause unregister_netdevice() to wait
until the socket has been release()d.
This patch does not suffice if we are not allowed to accept connect()s
referring to a device that we already acked a NETDEV_GOING_DOWN for
(that is: all references are only guaranteed to be freed after
NETDEV_DOWN has been acknowledged, not necessarily after the
NETDEV_GOING_DOWN already). And if we are allowed to, we could avoid
looking through the hash table upon NETDEV_GOING_DOWN completely and
only do that once we get the NETDEV_DOWN ...
mostrows:
pppoe_flush_dev is called on NETDEV_GOING_DOWN and NETDEV_DOWN to deal with
this "late connect" issue. Ideally one would hope to notify users at the
"NETDEV_GOING_DOWN" phase (just to pretend to be nice). However, it is the
NETDEV_DOWN scan that takes all the responsibility for ensuring nobody is
hanging around at that time.
Signed-off-by: Florian Zumbiehl <florz@florz.de>
Acked-by: Michal Ostrowski <mostrows@earthlink.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/pppoe.c')
-rw-r--r-- | drivers/net/pppoe.c | 19 |
1 files changed, 6 insertions, 13 deletions
diff --git a/drivers/net/pppoe.c b/drivers/net/pppoe.c index f761a9aae4c8..bc4fc30bc85e 100644 --- a/drivers/net/pppoe.c +++ b/drivers/net/pppoe.c @@ -218,17 +218,6 @@ static inline struct pppox_sock *get_item_by_addr(struct sockaddr_pppox *sp) return get_item(sp->sa_addr.pppoe.sid, sp->sa_addr.pppoe.remote, ifindex); } -static inline int set_item(struct pppox_sock *po) -{ - int i; - - write_lock_bh(&pppoe_hash_lock); - i = __set_item(po); - write_unlock_bh(&pppoe_hash_lock); - - return i; -} - static inline struct pppox_sock *delete_item(unsigned long sid, char *addr, int ifindex) { struct pppox_sock *ret; @@ -595,14 +584,18 @@ static int pppoe_connect(struct socket *sock, struct sockaddr *uservaddr, po->pppoe_dev = dev; po->pppoe_ifindex = dev->ifindex; - if (!(dev->flags & IFF_UP)) + write_lock_bh(&pppoe_hash_lock); + if (!(dev->flags & IFF_UP)){ + write_unlock_bh(&pppoe_hash_lock); goto err_put; + } memcpy(&po->pppoe_pa, &sp->sa_addr.pppoe, sizeof(struct pppoe_addr)); - error = set_item(po); + error = __set_item(po); + write_unlock_bh(&pppoe_hash_lock); if (error < 0) goto err_put; |