Merge branch 'gtp-fix-several-bugs'

Taehee Yoo says:

====================
gtp: fix several bugs

This patch series fixes several bugs in the gtp module.

First patch fixes suspicious RCU usage.
The problem is to use rcu_dereference_sk_user_data() outside of
RCU read critical section.

Second patch fixes use-after-free.
gtp_encap_destroy() is called twice.
gtp_encap_destroy() use both gtp->sk0 and gtp->sk1u.
these pointers can be freed in gtp_encap_destroy().
So, gtp_encap_destroy() should avoid using freed sk pointer.

Third patch removes duplicate code in gtp_dellink().
gtp_dellink() calls gtp_encap_disable() twice.
So, remove one of them.

Fourth patch fixes usage of GFP_KERNEL.
GFP_KERNEL can not be used in RCU read critical section.
This patch make ipv4_pdp_add() to use GFP_ATOMIC instead of GFP_KERNEL.

Fifth patch fixes use-after-free in gtp_newlink().
gtp_newlink() uses gtp_net which would be destroyed by the __exit_net
routine.
So, gtp_newlink should not be called after the __exit_net routine.

Sixth patch adds missing error handling routine in gtp_encap_enable().
gtp_encap_enable() will fail, if invalid role value is sent from
user-space. if so, gtp_encap_enable() should execute error handling
routine.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>