444 lines
12 KiB
C
444 lines
12 KiB
C
/*
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* llc_sap.c - driver routines for SAP component.
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*
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* Copyright (c) 1997 by Procom Technology, Inc.
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* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program can be redistributed or modified under the terms of the
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* GNU General Public License as published by the Free Software Foundation.
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* This program is distributed without any warranty or implied warranty
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* of merchantability or fitness for a particular purpose.
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*
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* See the GNU General Public License for more details.
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*/
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#include <net/llc.h>
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#include <net/llc_if.h>
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#include <net/llc_conn.h>
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#include <net/llc_pdu.h>
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#include <net/llc_sap.h>
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#include <net/llc_s_ac.h>
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#include <net/llc_s_ev.h>
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#include <net/llc_s_st.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <linux/llc.h>
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#include <linux/slab.h>
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static int llc_mac_header_len(unsigned short devtype)
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{
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switch (devtype) {
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case ARPHRD_ETHER:
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case ARPHRD_LOOPBACK:
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return sizeof(struct ethhdr);
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}
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return 0;
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}
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/**
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* llc_alloc_frame - allocates sk_buff for frame
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* @sk: socket to allocate frame to
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* @dev: network device this skb will be sent over
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* @type: pdu type to allocate
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* @data_size: data size to allocate
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*
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* Allocates an sk_buff for frame and initializes sk_buff fields.
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* Returns allocated skb or %NULL when out of memory.
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*/
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struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
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u8 type, u32 data_size)
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{
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int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
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struct sk_buff *skb;
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hlen += llc_mac_header_len(dev->type);
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skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
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if (skb) {
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skb_reset_mac_header(skb);
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skb_reserve(skb, hlen);
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skb_reset_network_header(skb);
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skb_reset_transport_header(skb);
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skb->protocol = htons(ETH_P_802_2);
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skb->dev = dev;
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if (sk != NULL)
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skb_set_owner_w(skb, sk);
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}
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return skb;
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}
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void llc_save_primitive(struct sock *sk, struct sk_buff *skb, u8 prim)
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{
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struct sockaddr_llc *addr;
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/* save primitive for use by the user. */
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addr = llc_ui_skb_cb(skb);
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memset(addr, 0, sizeof(*addr));
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addr->sllc_family = sk->sk_family;
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addr->sllc_arphrd = skb->dev->type;
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addr->sllc_test = prim == LLC_TEST_PRIM;
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addr->sllc_xid = prim == LLC_XID_PRIM;
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addr->sllc_ua = prim == LLC_DATAUNIT_PRIM;
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llc_pdu_decode_sa(skb, addr->sllc_mac);
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llc_pdu_decode_ssap(skb, &addr->sllc_sap);
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}
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/**
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* llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
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* @sap: pointer to SAP
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* @skb: received pdu
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*/
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void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
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switch (LLC_U_PDU_RSP(pdu)) {
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case LLC_1_PDU_CMD_TEST:
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ev->prim = LLC_TEST_PRIM; break;
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case LLC_1_PDU_CMD_XID:
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ev->prim = LLC_XID_PRIM; break;
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case LLC_1_PDU_CMD_UI:
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ev->prim = LLC_DATAUNIT_PRIM; break;
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}
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ev->ind_cfm_flag = LLC_IND;
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}
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/**
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* llc_find_sap_trans - finds transition for event
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* @sap: pointer to SAP
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* @skb: happened event
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*
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* This function finds transition that matches with happened event.
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* Returns the pointer to found transition on success or %NULL for
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* failure.
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*/
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static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
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struct sk_buff *skb)
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{
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int i = 0;
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struct llc_sap_state_trans *rc = NULL;
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struct llc_sap_state_trans **next_trans;
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struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
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/*
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* Search thru events for this state until list exhausted or until
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* its obvious the event is not valid for the current state
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*/
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for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
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if (!next_trans[i]->ev(sap, skb)) {
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rc = next_trans[i]; /* got event match; return it */
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break;
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}
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return rc;
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}
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/**
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* llc_exec_sap_trans_actions - execute actions related to event
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* @sap: pointer to SAP
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* @trans: pointer to transition that it's actions must be performed
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* @skb: happened event.
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*
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* This function executes actions that is related to happened event.
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* Returns 0 for success and 1 for failure of at least one action.
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*/
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static int llc_exec_sap_trans_actions(struct llc_sap *sap,
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struct llc_sap_state_trans *trans,
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struct sk_buff *skb)
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{
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int rc = 0;
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const llc_sap_action_t *next_action = trans->ev_actions;
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for (; next_action && *next_action; next_action++)
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if ((*next_action)(sap, skb))
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rc = 1;
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return rc;
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}
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/**
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* llc_sap_next_state - finds transition, execs actions & change SAP state
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* @sap: pointer to SAP
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* @skb: happened event
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*
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* This function finds transition that matches with happened event, then
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* executes related actions and finally changes state of SAP. It returns
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* 0 on success and 1 for failure.
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*/
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static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
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{
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int rc = 1;
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struct llc_sap_state_trans *trans;
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if (sap->state > LLC_NR_SAP_STATES)
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goto out;
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trans = llc_find_sap_trans(sap, skb);
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if (!trans)
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goto out;
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/*
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* Got the state to which we next transition; perform the actions
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* associated with this transition before actually transitioning to the
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* next state
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*/
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rc = llc_exec_sap_trans_actions(sap, trans, skb);
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if (rc)
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goto out;
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/*
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* Transition SAP to next state if all actions execute successfully
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*/
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sap->state = trans->next_state;
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out:
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return rc;
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}
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/**
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* llc_sap_state_process - sends event to SAP state machine
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* @sap: sap to use
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* @skb: pointer to occurred event
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*
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* After executing actions of the event, upper layer will be indicated
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* if needed(on receiving an UI frame). sk can be null for the
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* datalink_proto case.
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*
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* This function always consumes a reference to the skb.
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*/
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static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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ev->ind_cfm_flag = 0;
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llc_sap_next_state(sap, skb);
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if (ev->ind_cfm_flag == LLC_IND && skb->sk->sk_state != TCP_LISTEN) {
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llc_save_primitive(skb->sk, skb, ev->prim);
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/* queue skb to the user. */
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if (sock_queue_rcv_skb(skb->sk, skb) == 0)
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return;
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}
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kfree_skb(skb);
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}
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/**
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* llc_build_and_send_test_pkt - TEST interface for upper layers.
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* @sap: sap to use
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* @skb: packet to send
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* @dmac: destination mac address
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* @dsap: destination sap
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*
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* This function is called when upper layer wants to send a TEST pdu.
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* Returns 0 for success, 1 otherwise.
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*/
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void llc_build_and_send_test_pkt(struct llc_sap *sap,
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struct sk_buff *skb, u8 *dmac, u8 dsap)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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ev->saddr.lsap = sap->laddr.lsap;
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ev->daddr.lsap = dsap;
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memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
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memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
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ev->type = LLC_SAP_EV_TYPE_PRIM;
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ev->prim = LLC_TEST_PRIM;
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ev->prim_type = LLC_PRIM_TYPE_REQ;
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llc_sap_state_process(sap, skb);
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}
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/**
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* llc_build_and_send_xid_pkt - XID interface for upper layers
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* @sap: sap to use
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* @skb: packet to send
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* @dmac: destination mac address
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* @dsap: destination sap
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*
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* This function is called when upper layer wants to send a XID pdu.
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* Returns 0 for success, 1 otherwise.
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*/
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void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
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u8 *dmac, u8 dsap)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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ev->saddr.lsap = sap->laddr.lsap;
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ev->daddr.lsap = dsap;
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memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
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memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
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ev->type = LLC_SAP_EV_TYPE_PRIM;
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ev->prim = LLC_XID_PRIM;
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ev->prim_type = LLC_PRIM_TYPE_REQ;
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llc_sap_state_process(sap, skb);
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}
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/**
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* llc_sap_rcv - sends received pdus to the sap state machine
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* @sap: current sap component structure.
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* @skb: received frame.
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* @sk: socket to associate to frame
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*
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* Sends received pdus to the sap state machine.
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*/
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static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
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struct sock *sk)
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{
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struct llc_sap_state_ev *ev = llc_sap_ev(skb);
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ev->type = LLC_SAP_EV_TYPE_PDU;
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ev->reason = 0;
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skb_orphan(skb);
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sock_hold(sk);
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skb->sk = sk;
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skb->destructor = sock_efree;
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llc_sap_state_process(sap, skb);
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}
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static inline bool llc_dgram_match(const struct llc_sap *sap,
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const struct llc_addr *laddr,
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const struct sock *sk,
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const struct net *net)
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{
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struct llc_sock *llc = llc_sk(sk);
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return sk->sk_type == SOCK_DGRAM &&
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net_eq(sock_net(sk), net) &&
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llc->laddr.lsap == laddr->lsap &&
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ether_addr_equal(llc->laddr.mac, laddr->mac);
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}
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/**
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* llc_lookup_dgram - Finds dgram socket for the local sap/mac
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* @sap: SAP
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* @laddr: address of local LLC (MAC + SAP)
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* @net: netns to look up a socket in
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*
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* Search socket list of the SAP and finds connection using the local
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* mac, and local sap. Returns pointer for socket found, %NULL otherwise.
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*/
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static struct sock *llc_lookup_dgram(struct llc_sap *sap,
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const struct llc_addr *laddr,
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const struct net *net)
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{
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struct sock *rc;
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struct hlist_nulls_node *node;
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int slot = llc_sk_laddr_hashfn(sap, laddr);
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struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
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rcu_read_lock_bh();
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again:
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sk_nulls_for_each_rcu(rc, node, laddr_hb) {
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if (llc_dgram_match(sap, laddr, rc, net)) {
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/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
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if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
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goto again;
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if (unlikely(llc_sk(rc)->sap != sap ||
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!llc_dgram_match(sap, laddr, rc, net))) {
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sock_put(rc);
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continue;
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}
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goto found;
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}
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}
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rc = NULL;
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/*
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* if the nulls value we got at the end of this lookup is
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* not the expected one, we must restart lookup.
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* We probably met an item that was moved to another chain.
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*/
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if (unlikely(get_nulls_value(node) != slot))
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goto again;
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found:
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rcu_read_unlock_bh();
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return rc;
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}
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static inline bool llc_mcast_match(const struct llc_sap *sap,
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const struct llc_addr *laddr,
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const struct sk_buff *skb,
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const struct sock *sk)
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{
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struct llc_sock *llc = llc_sk(sk);
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return sk->sk_type == SOCK_DGRAM &&
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llc->laddr.lsap == laddr->lsap &&
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llc->dev == skb->dev;
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}
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static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
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struct sock **stack, int count)
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{
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struct sk_buff *skb1;
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int i;
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for (i = 0; i < count; i++) {
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skb1 = skb_clone(skb, GFP_ATOMIC);
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if (!skb1) {
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sock_put(stack[i]);
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continue;
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}
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llc_sap_rcv(sap, skb1, stack[i]);
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sock_put(stack[i]);
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}
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}
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/**
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* llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
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* @sap: SAP
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* @laddr: address of local LLC (MAC + SAP)
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* @skb: PDU to deliver
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*
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* Search socket list of the SAP and finds connections with same sap.
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* Deliver clone to each.
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*/
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static void llc_sap_mcast(struct llc_sap *sap,
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const struct llc_addr *laddr,
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struct sk_buff *skb)
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{
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int i = 0;
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struct sock *sk;
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struct sock *stack[256 / sizeof(struct sock *)];
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struct llc_sock *llc;
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struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
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spin_lock_bh(&sap->sk_lock);
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hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
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sk = &llc->sk;
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if (!llc_mcast_match(sap, laddr, skb, sk))
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continue;
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sock_hold(sk);
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if (i < ARRAY_SIZE(stack))
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stack[i++] = sk;
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else {
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llc_do_mcast(sap, skb, stack, i);
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i = 0;
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}
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}
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spin_unlock_bh(&sap->sk_lock);
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llc_do_mcast(sap, skb, stack, i);
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}
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void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
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{
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struct llc_addr laddr;
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llc_pdu_decode_da(skb, laddr.mac);
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llc_pdu_decode_dsap(skb, &laddr.lsap);
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if (is_multicast_ether_addr(laddr.mac)) {
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llc_sap_mcast(sap, &laddr, skb);
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kfree_skb(skb);
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} else {
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struct sock *sk = llc_lookup_dgram(sap, &laddr, dev_net(skb->dev));
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if (sk) {
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llc_sap_rcv(sap, skb, sk);
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sock_put(sk);
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} else
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kfree_skb(skb);
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}
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}
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