On 22.03.2018 12:44, Kirill Tkhai wrote:
> Commit 1215e51edad1 "ipv4: fix a deadlock in ip_ra_control"
> made rtnl_lock() be used in raw_close(). This function is called
> on every RAW socket destruction, so that rtnl_mutex is taken
> every time. This scales very sadly. I observe cleanup_net()
> spending a lot of time in rtnl_lock() and raw_close() is one
> of the biggest rtnl user (since we have percpu net->ipv4.icmp_sk).
>
> This patchset reworks the locking: reverts the problem commit
> and its descendant, and introduces rtnl-independent locking.
> This may have a continuation, and someone may work on killing
> rtnl_lock() in mrtsock_destruct() in the future.
>
> Thanks,
> Kirill
>
> ---
> v3: Change patches order: [2/5] and [3/5].
> v2: Fix sparse warning [4/5], as reported by kbuild test robot.
>
> ---
>
> Kirill Tkhai (5):
> net: Revert "ipv4: get rid of ip_ra_lock"
> net: Move IP_ROUTER_ALERT out of lock_sock(sk)
> net: Revert "ipv4: fix a deadlock in ip_ra_control"
> net: Make ip_ra_chain per struct net
> net: Replace ip_ra_lock with per-net mutex
>
>
> include/net/ip.h | 13 +++++++++++--
> include/net/netns/ipv4.h | 2 ++
> net/core/net_namespace.c | 1 +
> net/ipv4/ip_input.c | 5 ++---
> net/ipv4/ip_sockglue.c | 34 +++++++++++++---------------------
> net/ipv4/ipmr.c | 11 +++++++++--
> net/ipv4/raw.c | 2 --
> 7 files changed, 38 insertions(+), 30 deletions(-)
>
> --
> Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
JFI: I used the below program to test:
#define _GNU_SOURCE
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <linux/mroute.h>
#include <sched.h>
int main()
{
int sk, v, i = 0;
if (unshare(CLONE_NEWNET)) {
perror("unshare");
return 1;
}
sk = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
if (sk < 0) {
perror("socket");
return 1;
}
for (i = 0; i < 3; i++)
fork();
while (1) {
setsockopt(sk, IPPROTO_IP, MRT_INIT, (void *)&v, sizeof(v));
setsockopt(sk, IPPROTO_IP, MRT_DONE, (void *)&v, sizeof(v));
v = (i++)%2;
setsockopt(sk, IPPROTO_IP, IP_ROUTER_ALERT, (void *)&v,
sizeof(v));
}
return 0;
}
