linux/include
Eric Dumazet d7d99872c1 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>
2019-06-19 11:37:47 -04:00
..
acpi treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
asm-generic treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
clocksource treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 335 2019-06-05 17:37:06 +02:00
drm meson: A few G12A fixes across the driver (Neil) 2019-06-14 11:36:30 +02:00
dt-bindings Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 20:20:36 -07:00
keys treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
kvm treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 342 2019-06-05 17:37:07 +02:00
linux flow_dissector: add support for ingress ifindex dissection 2019-06-19 10:09:21 -04:00
math-emu math-emu: Use statement expressions to fix Wshift-count-overflow warning 2019-05-31 15:23:25 +08:00
media treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 316 2019-06-05 17:37:05 +02:00
memory
misc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
net netns: add pre_exit method to struct pernet_operations 2019-06-19 11:37:47 -04:00
pcmcia
ras
rdma SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
scsi treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 335 2019-06-05 17:37:06 +02:00
soc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 399 2019-06-05 17:37:12 +02:00
sound sound fixes for 5.2-rc5 2019-06-14 05:37:06 -10:00
target
trace page_pool: add tracepoints for page_pool with details need by XDP 2019-06-19 11:23:13 -04:00
uapi act_ctinfo: Don't use BIT() in UAPI headers. 2019-06-19 10:12:58 -04:00
video treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428 2019-06-05 17:37:16 +02:00
xen