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authorEric Dumazet <edumazet@google.com>2019-06-18 21:08:59 +0300
committerDavid S. Miller <davem@davemloft.net>2019-06-19 18:37:47 +0300
commitd7d99872c144a2c2f5d9c9d83627fa833836cba5 (patch)
treef3a83dacc74fbe6c81665fb4c46ac2572173fcc8 /include
parent2a54003e7af1eaddc05848dac14f7bcd77301478 (diff)
downloadlinux-d7d99872c144a2c2f5d9c9d83627fa833836cba5.tar.xz
netns: add pre_exit method to struct pernet_operations
Current struct pernet_operations exit() handlers are highly discouraged to call synchronize_rcu(). There are cases where we need them, and exit_batch() does not help the common case where a single netns is dismantled. This patch leverages the existing synchronize_rcu() call in cleanup_net() Calling optional ->pre_exit() method before ->exit() or ->exit_batch() allows to benefit from a single synchronize_rcu() call. Note that the synchronize_rcu() calls added in this patch are only in error paths or slow paths. Tested: $ time for i in {1..1000}; do unshare -n /bin/false;done real 0m2.612s user 0m0.171s sys 0m2.216s Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/net_namespace.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index abb4f92456e1..ad9243afac67 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -355,8 +355,13 @@ struct pernet_operations {
* synchronize_rcu() related to these pernet_operations,
* instead of separate synchronize_rcu() for every net.
* Please, avoid synchronize_rcu() at all, where it's possible.
+ *
+ * Note that a combination of pre_exit() and exit() can
+ * be used, since a synchronize_rcu() is guaranteed between
+ * the calls.
*/
int (*init)(struct net *net);
+ void (*pre_exit)(struct net *net);
void (*exit)(struct net *net);
void (*exit_batch)(struct list_head *net_exit_list);
unsigned int *id;