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net: dont hold rtnl mutex during netlink dump callbacks

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Four years ago, Patrick made a change to hold rtnl mutex during netlink
dump callbacks.

I believe it was a wrong move. This slows down concurrent dumps, making
good old /proc/net/ files faster than rtnetlink in some situations.

This occurred to me because one "ip link show dev ..." was _very_ slow
on a workload adding/removing network devices in background.

All dump callbacks are able to use RCU locking now, so this patch does
roughly a revert of commits :

1c2d670f36 : [RTNETLINK]: Hold rtnl_mutex during netlink dump callbacks
6313c1e099 : [RTNETLINK]: Remove unnecessary locking in dump callbacks

This let writers fight for rtnl mutex and readers going full speed.

It also takes care of phonet : phonet_route_get() is now called from rcu
read section. I renamed it to phonet_route_get_rcu()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2011-04-27 22:56:07 +00:00
committed by David S. Miller
parent dcfd9cdc12
commit e67f88dd12
8 changed files with 25 additions and 23 deletions
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2
include/net/phonet/pn_dev.h
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@@ -51,7 +51,7 @@ void phonet_address_notify(int event, struct net_device *dev, u8 addr);
int phonet_route_add(struct net_device *dev, u8 daddr);
int phonet_route_del(struct net_device *dev, u8 daddr);
void rtm_phonet_notify(int event, struct net_device *dev, u8 dst);
struct net_device *phonet_route_get(struct net *net, u8 daddr);
struct net_device *phonet_route_get_rcu(struct net *net, u8 daddr);
struct net_device *phonet_route_output(struct net *net, u8 daddr);
#define PN_NO_ADDR 0xff