linux/net/core
Eric Dumazet ef885afbf8 net: use rcu_barrier() in rollback_registered_many
netdev_wait_allrefs() waits that all references to a device vanishes.

It currently uses a _very_ pessimistic 250 ms delay between each probe.
Some users reported that no more than 4 devices can be dismantled per
second, this is a pretty serious problem for some setups.

Most of the time, a refcount is about to be released by an RCU callback,
that is still in flight because rollback_registered_many() uses a
synchronize_rcu() call instead of rcu_barrier(). Problem is visible if
number of online cpus is one, because synchronize_rcu() is then a no op.

time to remove 50 ipip tunnels on a UP machine :

before patch : real 11.910s
after patch : real 1.250s

Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reported-by: Octavian Purdila <opurdila@ixiacom.com>
Reported-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-09-14 14:27:29 -07:00
..
Makefile
datagram.c
dev.c net: use rcu_barrier() in rollback_registered_many 2010-09-14 14:27:29 -07:00
dev_addr_lists.c
drop_monitor.c
dst.c
ethtool.c
fib_rules.c
filter.c
flow.c
gen_estimator.c
gen_stats.c
iovec.c
kmap_skb.h
link_watch.c
neighbour.c
net-sysfs.c
net-sysfs.h
net-traces.c
net_namespace.c
netevent.c
netpoll.c
pktgen.c
request_sock.c
rtnetlink.c
scm.c
skbuff.c
sock.c
stream.c
sysctl_net_core.c
timestamping.c
user_dma.c
utils.c