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genetlink: hold read cb_lock during iteration of genl_fam_idr in genl_bind() 

In genl_bind(), currently genl_lock and write cb_lock are taken
for iteration of genl_fam_idr and processing of static values
stored in struct genl_family. Take just read cb_lock for this task
as it is sufficient to guard the idr and the struct against
concurrent genl_register/unregister_family() calls.

This will allow to run genl command processing in genl_rcv() and
mnl_socket_setsockopt(.., NETLINK_ADD_MEMBERSHIP, ..) in parallel.

Reported-by: Vikas Gupta <vikas.gupta@broadcom.com>
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20220825081940.1283335-1-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jiri Pirko 2022-08-25 10:19:40 +02:00 committed by Jakub Kicinski
parent 0c1f77d87d
commit 8f1948bdcf
1 changed files with 2 additions and 2 deletions
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4
net/netlink/genetlink.c
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@ -1362,7 +1362,7 @@ static int genl_bind(struct net *net, int group)
unsigned int id;
int ret = 0;
genl_lock_all();
down_read(&cb_lock);
idr_for_each_entry(&genl_fam_idr, family, id) {
const struct genl_multicast_group *grp;
@ -1383,7 +1383,7 @@ static int genl_bind(struct net *net, int group)
break;
}
genl_unlock_all();
up_read(&cb_lock);
return ret;
}