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f0b07bb151
rtnl_lock() is used everywhere, and contention is very high. When someone wants to iterate over alive net namespaces, he/she has no a possibility to do that without exclusive lock. But the exclusive rtnl_lock() in such places is overkill, and it just increases the contention. Yes, there is already for_each_net_rcu() in kernel, but it requires rcu_read_lock(), and this can't be sleepable. Also, sometimes it may be need really prevent net_namespace_list growth, so for_each_net_rcu() is not fit there. This patch introduces new rw_semaphore, which will be used instead of rtnl_mutex to protect net_namespace_list. It is sleepable and allows not-exclusive iterations over net namespaces list. It allows to stop using rtnl_lock() in several places (what is made in next patches) and makes less the time, we keep rtnl_mutex. Here we just add new lock, while the explanation of we can remove rtnl_lock() there are in next patches. Fine grained locks generally are better, then one big lock, so let's do that with net_namespace_list, while the situation allows that. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| include | ||
| ss | ||
| .gitignore | ||
| avc.c | ||
| exports.c | ||
| hooks.c | ||
| ibpkey.c | ||
| Kconfig | ||
| Makefile | ||
| netif.c | ||
| netlabel.c | ||
| netlink.c | ||
| netnode.c | ||
| netport.c | ||
| nlmsgtab.c | ||
| selinuxfs.c | ||
| xfrm.c | ||