mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 16:29:59 +00:00
![Mark Rutland](/assets/img/avatar_default.png)
Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
226 lines
5.9 KiB
C
226 lines
5.9 KiB
C
/*
|
|
* llc_input.c - Minimal input path for LLC
|
|
*
|
|
* Copyright (c) 1997 by Procom Technology, Inc.
|
|
* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
|
|
*
|
|
* This program can be redistributed or modified under the terms of the
|
|
* GNU General Public License as published by the Free Software Foundation.
|
|
* This program is distributed without any warranty or implied warranty
|
|
* of merchantability or fitness for a particular purpose.
|
|
*
|
|
* See the GNU General Public License for more details.
|
|
*/
|
|
#include <linux/netdevice.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/export.h>
|
|
#include <net/net_namespace.h>
|
|
#include <net/llc.h>
|
|
#include <net/llc_pdu.h>
|
|
#include <net/llc_sap.h>
|
|
|
|
#if 0
|
|
#define dprintk(args...) printk(KERN_DEBUG args)
|
|
#else
|
|
#define dprintk(args...)
|
|
#endif
|
|
|
|
/*
|
|
* Packet handler for the station, registerable because in the minimal
|
|
* LLC core that is taking shape only the very minimal subset of LLC that
|
|
* is needed for things like IPX, Appletalk, etc will stay, with all the
|
|
* rest in the llc1 and llc2 modules.
|
|
*/
|
|
static void (*llc_station_handler)(struct sk_buff *skb);
|
|
|
|
/*
|
|
* Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
|
|
*/
|
|
static void (*llc_type_handlers[2])(struct llc_sap *sap,
|
|
struct sk_buff *skb);
|
|
|
|
void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
|
|
struct sk_buff *skb))
|
|
{
|
|
smp_wmb(); /* ensure initialisation is complete before it's called */
|
|
if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
|
|
llc_type_handlers[type - 1] = handler;
|
|
}
|
|
|
|
void llc_remove_pack(int type)
|
|
{
|
|
if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
|
|
llc_type_handlers[type - 1] = NULL;
|
|
synchronize_net();
|
|
}
|
|
|
|
void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
|
|
{
|
|
/* Ensure initialisation is complete before it's called */
|
|
if (handler)
|
|
smp_wmb();
|
|
|
|
llc_station_handler = handler;
|
|
|
|
if (!handler)
|
|
synchronize_net();
|
|
}
|
|
|
|
/**
|
|
* llc_pdu_type - returns which LLC component must handle for PDU
|
|
* @skb: input skb
|
|
*
|
|
* This function returns which LLC component must handle this PDU.
|
|
*/
|
|
static __inline__ int llc_pdu_type(struct sk_buff *skb)
|
|
{
|
|
int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
|
|
struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
|
|
|
|
if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
|
|
goto out;
|
|
switch (LLC_U_PDU_CMD(pdu)) {
|
|
case LLC_1_PDU_CMD_XID:
|
|
case LLC_1_PDU_CMD_UI:
|
|
case LLC_1_PDU_CMD_TEST:
|
|
type = LLC_DEST_SAP;
|
|
break;
|
|
case LLC_2_PDU_CMD_SABME:
|
|
case LLC_2_PDU_CMD_DISC:
|
|
case LLC_2_PDU_RSP_UA:
|
|
case LLC_2_PDU_RSP_DM:
|
|
case LLC_2_PDU_RSP_FRMR:
|
|
break;
|
|
default:
|
|
type = LLC_DEST_INVALID;
|
|
break;
|
|
}
|
|
out:
|
|
return type;
|
|
}
|
|
|
|
/**
|
|
* llc_fixup_skb - initializes skb pointers
|
|
* @skb: This argument points to incoming skb
|
|
*
|
|
* Initializes internal skb pointer to start of network layer by deriving
|
|
* length of LLC header; finds length of LLC control field in LLC header
|
|
* by looking at the two lowest-order bits of the first control field
|
|
* byte; field is either 3 or 4 bytes long.
|
|
*/
|
|
static inline int llc_fixup_skb(struct sk_buff *skb)
|
|
{
|
|
u8 llc_len = 2;
|
|
struct llc_pdu_un *pdu;
|
|
|
|
if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
|
|
return 0;
|
|
|
|
pdu = (struct llc_pdu_un *)skb->data;
|
|
if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
|
|
llc_len = 1;
|
|
llc_len += 2;
|
|
|
|
if (unlikely(!pskb_may_pull(skb, llc_len)))
|
|
return 0;
|
|
|
|
skb->transport_header += llc_len;
|
|
skb_pull(skb, llc_len);
|
|
if (skb->protocol == htons(ETH_P_802_2)) {
|
|
__be16 pdulen = eth_hdr(skb)->h_proto;
|
|
s32 data_size = ntohs(pdulen) - llc_len;
|
|
|
|
if (data_size < 0 ||
|
|
!pskb_may_pull(skb, data_size))
|
|
return 0;
|
|
if (unlikely(pskb_trim_rcsum(skb, data_size)))
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* llc_rcv - 802.2 entry point from net lower layers
|
|
* @skb: received pdu
|
|
* @dev: device that receive pdu
|
|
* @pt: packet type
|
|
*
|
|
* When the system receives a 802.2 frame this function is called. It
|
|
* checks SAP and connection of received pdu and passes frame to
|
|
* llc_{station,sap,conn}_rcv for sending to proper state machine. If
|
|
* the frame is related to a busy connection (a connection is sending
|
|
* data now), it queues this frame in the connection's backlog.
|
|
*/
|
|
int llc_rcv(struct sk_buff *skb, struct net_device *dev,
|
|
struct packet_type *pt, struct net_device *orig_dev)
|
|
{
|
|
struct llc_sap *sap;
|
|
struct llc_pdu_sn *pdu;
|
|
int dest;
|
|
int (*rcv)(struct sk_buff *, struct net_device *,
|
|
struct packet_type *, struct net_device *);
|
|
void (*sta_handler)(struct sk_buff *skb);
|
|
void (*sap_handler)(struct llc_sap *sap, struct sk_buff *skb);
|
|
|
|
if (!net_eq(dev_net(dev), &init_net))
|
|
goto drop;
|
|
|
|
/*
|
|
* When the interface is in promisc. mode, drop all the crap that it
|
|
* receives, do not try to analyse it.
|
|
*/
|
|
if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
|
|
dprintk("%s: PACKET_OTHERHOST\n", __func__);
|
|
goto drop;
|
|
}
|
|
skb = skb_share_check(skb, GFP_ATOMIC);
|
|
if (unlikely(!skb))
|
|
goto out;
|
|
if (unlikely(!llc_fixup_skb(skb)))
|
|
goto drop;
|
|
pdu = llc_pdu_sn_hdr(skb);
|
|
if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
|
|
goto handle_station;
|
|
sap = llc_sap_find(pdu->dsap);
|
|
if (unlikely(!sap)) {/* unknown SAP */
|
|
dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
|
|
pdu->dsap);
|
|
goto drop;
|
|
}
|
|
/*
|
|
* First the upper layer protocols that don't need the full
|
|
* LLC functionality
|
|
*/
|
|
rcv = rcu_dereference(sap->rcv_func);
|
|
dest = llc_pdu_type(skb);
|
|
sap_handler = dest ? READ_ONCE(llc_type_handlers[dest - 1]) : NULL;
|
|
if (unlikely(!sap_handler)) {
|
|
if (rcv)
|
|
rcv(skb, dev, pt, orig_dev);
|
|
else
|
|
kfree_skb(skb);
|
|
} else {
|
|
if (rcv) {
|
|
struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
|
|
if (cskb)
|
|
rcv(cskb, dev, pt, orig_dev);
|
|
}
|
|
sap_handler(sap, skb);
|
|
}
|
|
llc_sap_put(sap);
|
|
out:
|
|
return 0;
|
|
drop:
|
|
kfree_skb(skb);
|
|
goto out;
|
|
handle_station:
|
|
sta_handler = READ_ONCE(llc_station_handler);
|
|
if (!sta_handler)
|
|
goto drop;
|
|
sta_handler(skb);
|
|
goto out;
|
|
}
|
|
|
|
EXPORT_SYMBOL(llc_add_pack);
|
|
EXPORT_SYMBOL(llc_remove_pack);
|
|
EXPORT_SYMBOL(llc_set_station_handler);
|