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freebsd-skq/sys/net/ifq.h
Sepherosa Ziehau 1321c5029e buf_ring/drbr: Add buf_ring_peek_clear_sc and use it in drbr_peek 
Unlike buf_ring_peek, it only supports single consumer mode, and it
clears the cons_head if DEBUG_BUFRING/INVARIANTS is defined.

The normal use case of drbr_peek for network drivers is:

m = drbr_peek(br);
err = hw_spec_encap(&m); /* could m_defrag/m_collapse */
(*)
if (err) {
    if (m == NULL)
        drbr_advance(br);
    else
        drbr_putback(br, m);
    /* break the loop */
}
drbr_advance(br);

The race is:
If hw_spec_encap() m_defrag or m_collapse the mbuf, i.e. the old mbuf
was freed, or like the Hyper-V's network driver, that transmission-
done does not even require the TX lock; then on the other CPU at the
(*) time, the freed mbuf could be recycled and being drbr_enqueue even
before the current CPU had the chance to call drbr_{advance,putback}.
This triggers a panic in drbr_enqueue duplicated element check, if
DEBUG_BUFRING/INVARIANTS is defined.

Use buf_ring_peek_clear_sc() in drbr_peek() to fix the above race.

This change is a NO-OP, if neither DEBUG_BUFRING nor INVARIANTS are
defined.

MFC after:	1 week
Sponsored by:	Microsoft OSTC
Differential Revision:	https://reviews.freebsd.org/D5416
2016-02-29 03:54:51 +00:00

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/*-
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* From: @(#)if.h 8.1 (Berkeley) 6/10/93
* $FreeBSD$
*/
#ifndef _NET_IFQ_H_
#define _NET_IFQ_H_
#ifdef _KERNEL
#include <sys/mbuf.h> /* ifqueue only? */
#include <sys/buf_ring.h>
#include <net/vnet.h>
#endif /* _KERNEL */
#include <sys/lock.h> /* XXX */
#include <sys/mutex.h> /* struct ifqueue */
/*
* Couple of ugly extra definitions that are required since ifq.h
* is splitted from if_var.h.
*/
#define IF_DUNIT_NONE -1
#include <net/altq/if_altq.h>
/*
* Structure defining a queue for a network interface.
*/
struct ifqueue {
struct mbuf *ifq_head;
struct mbuf *ifq_tail;
int ifq_len;
int ifq_maxlen;
struct mtx ifq_mtx;
};
#ifdef _KERNEL
/*
* Output queues (ifp->if_snd) and slow device input queues (*ifp->if_slowq)
* are queues of messages stored on ifqueue structures
* (defined above). Entries are added to and deleted from these structures
* by these macros.
*/
#define IF_LOCK(ifq) mtx_lock(&(ifq)->ifq_mtx)
#define IF_UNLOCK(ifq) mtx_unlock(&(ifq)->ifq_mtx)
#define IF_LOCK_ASSERT(ifq) mtx_assert(&(ifq)->ifq_mtx, MA_OWNED)
#define _IF_QFULL(ifq) ((ifq)->ifq_len >= (ifq)->ifq_maxlen)
#define _IF_QLEN(ifq) ((ifq)->ifq_len)
#define _IF_ENQUEUE(ifq, m) do { \
(m)->m_nextpkt = NULL; \
if ((ifq)->ifq_tail == NULL) \
(ifq)->ifq_head = m; \
else \
(ifq)->ifq_tail->m_nextpkt = m; \
(ifq)->ifq_tail = m; \
(ifq)->ifq_len++; \
} while (0)
#define IF_ENQUEUE(ifq, m) do { \
IF_LOCK(ifq); \
_IF_ENQUEUE(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define _IF_PREPEND(ifq, m) do { \
(m)->m_nextpkt = (ifq)->ifq_head; \
if ((ifq)->ifq_tail == NULL) \
(ifq)->ifq_tail = (m); \
(ifq)->ifq_head = (m); \
(ifq)->ifq_len++; \
} while (0)
#define IF_PREPEND(ifq, m) do { \
IF_LOCK(ifq); \
_IF_PREPEND(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define _IF_DEQUEUE(ifq, m) do { \
(m) = (ifq)->ifq_head; \
if (m) { \
if (((ifq)->ifq_head = (m)->m_nextpkt) == NULL) \
(ifq)->ifq_tail = NULL; \
(m)->m_nextpkt = NULL; \
(ifq)->ifq_len--; \
} \
} while (0)
#define IF_DEQUEUE(ifq, m) do { \
IF_LOCK(ifq); \
_IF_DEQUEUE(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define _IF_DEQUEUE_ALL(ifq, m) do { \
(m) = (ifq)->ifq_head; \
(ifq)->ifq_head = (ifq)->ifq_tail = NULL; \
(ifq)->ifq_len = 0; \
} while (0)
#define IF_DEQUEUE_ALL(ifq, m) do { \
IF_LOCK(ifq); \
_IF_DEQUEUE_ALL(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define _IF_POLL(ifq, m) ((m) = (ifq)->ifq_head)
#define IF_POLL(ifq, m) _IF_POLL(ifq, m)
#define _IF_DRAIN(ifq) do { \
struct mbuf *m; \
for (;;) { \
_IF_DEQUEUE(ifq, m); \
if (m == NULL) \
break; \
m_freem(m); \
} \
} while (0)
#define IF_DRAIN(ifq) do { \
IF_LOCK(ifq); \
_IF_DRAIN(ifq); \
IF_UNLOCK(ifq); \
} while(0)
int if_handoff(struct ifqueue *ifq, struct mbuf *m, struct ifnet *ifp,
int adjust);
#define IF_HANDOFF(ifq, m, ifp) \
if_handoff((struct ifqueue *)ifq, m, ifp, 0)
#define IF_HANDOFF_ADJ(ifq, m, ifp, adj) \
if_handoff((struct ifqueue *)ifq, m, ifp, adj)
void if_start(struct ifnet *);
#define IFQ_ENQUEUE(ifq, m, err) \
do { \
IF_LOCK(ifq); \
if (ALTQ_IS_ENABLED(ifq)) \
ALTQ_ENQUEUE(ifq, m, NULL, err); \
else { \
if (_IF_QFULL(ifq)) { \
m_freem(m); \
(err) = ENOBUFS; \
} else { \
_IF_ENQUEUE(ifq, m); \
(err) = 0; \
} \
} \
IF_UNLOCK(ifq); \
} while (0)
#define IFQ_DEQUEUE_NOLOCK(ifq, m) \
do { \
if (TBR_IS_ENABLED(ifq)) \
(m) = tbr_dequeue_ptr(ifq, ALTDQ_REMOVE); \
else if (ALTQ_IS_ENABLED(ifq)) \
ALTQ_DEQUEUE(ifq, m); \
else \
_IF_DEQUEUE(ifq, m); \
} while (0)
#define IFQ_DEQUEUE(ifq, m) \
do { \
IF_LOCK(ifq); \
IFQ_DEQUEUE_NOLOCK(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define IFQ_POLL_NOLOCK(ifq, m) \
do { \
if (TBR_IS_ENABLED(ifq)) \
(m) = tbr_dequeue_ptr(ifq, ALTDQ_POLL); \
else if (ALTQ_IS_ENABLED(ifq)) \
ALTQ_POLL(ifq, m); \
else \
_IF_POLL(ifq, m); \
} while (0)
#define IFQ_POLL(ifq, m) \
do { \
IF_LOCK(ifq); \
IFQ_POLL_NOLOCK(ifq, m); \
IF_UNLOCK(ifq); \
} while (0)
#define IFQ_PURGE_NOLOCK(ifq) \
do { \
if (ALTQ_IS_ENABLED(ifq)) { \
ALTQ_PURGE(ifq); \
} else \
_IF_DRAIN(ifq); \
} while (0)
#define IFQ_PURGE(ifq) \
do { \
IF_LOCK(ifq); \
IFQ_PURGE_NOLOCK(ifq); \
IF_UNLOCK(ifq); \
} while (0)
#define IFQ_SET_READY(ifq) \
do { ((ifq)->altq_flags |= ALTQF_READY); } while (0)
#define IFQ_LOCK(ifq) IF_LOCK(ifq)
#define IFQ_UNLOCK(ifq) IF_UNLOCK(ifq)
#define IFQ_LOCK_ASSERT(ifq) IF_LOCK_ASSERT(ifq)
#define IFQ_IS_EMPTY(ifq) ((ifq)->ifq_len == 0)
#define IFQ_INC_LEN(ifq) ((ifq)->ifq_len++)
#define IFQ_DEC_LEN(ifq) (--(ifq)->ifq_len)
#define IFQ_SET_MAXLEN(ifq, len) ((ifq)->ifq_maxlen = (len))
/*
* The IFF_DRV_OACTIVE test should really occur in the device driver, not in
* the handoff logic, as that flag is locked by the device driver.
*/
#define IFQ_HANDOFF_ADJ(ifp, m, adj, err) \
do { \
int len; \
short mflags; \
\
len = (m)->m_pkthdr.len; \
mflags = (m)->m_flags; \
IFQ_ENQUEUE(&(ifp)->if_snd, m, err); \
if ((err) == 0) { \
if_inc_counter((ifp), IFCOUNTER_OBYTES, len + (adj)); \
if (mflags & M_MCAST) \
if_inc_counter((ifp), IFCOUNTER_OMCASTS, 1); \
if (((ifp)->if_drv_flags & IFF_DRV_OACTIVE) == 0) \
if_start(ifp); \
} else \
if_inc_counter((ifp), IFCOUNTER_OQDROPS, 1); \
} while (0)
#define IFQ_HANDOFF(ifp, m, err) \
IFQ_HANDOFF_ADJ(ifp, m, 0, err)
#define IFQ_DRV_DEQUEUE(ifq, m) \
do { \
(m) = (ifq)->ifq_drv_head; \
if (m) { \
if (((ifq)->ifq_drv_head = (m)->m_nextpkt) == NULL) \
(ifq)->ifq_drv_tail = NULL; \
(m)->m_nextpkt = NULL; \
(ifq)->ifq_drv_len--; \
} else { \
IFQ_LOCK(ifq); \
IFQ_DEQUEUE_NOLOCK(ifq, m); \
while ((ifq)->ifq_drv_len < (ifq)->ifq_drv_maxlen) { \
struct mbuf *m0; \
IFQ_DEQUEUE_NOLOCK(ifq, m0); \
if (m0 == NULL) \
break; \
m0->m_nextpkt = NULL; \
if ((ifq)->ifq_drv_tail == NULL) \
(ifq)->ifq_drv_head = m0; \
else \
(ifq)->ifq_drv_tail->m_nextpkt = m0; \
(ifq)->ifq_drv_tail = m0; \
(ifq)->ifq_drv_len++; \
} \
IFQ_UNLOCK(ifq); \
} \
} while (0)
#define IFQ_DRV_PREPEND(ifq, m) \
do { \
(m)->m_nextpkt = (ifq)->ifq_drv_head; \
if ((ifq)->ifq_drv_tail == NULL) \
(ifq)->ifq_drv_tail = (m); \
(ifq)->ifq_drv_head = (m); \
(ifq)->ifq_drv_len++; \
} while (0)
#define IFQ_DRV_IS_EMPTY(ifq) \
(((ifq)->ifq_drv_len == 0) && ((ifq)->ifq_len == 0))
#define IFQ_DRV_PURGE(ifq) \
do { \
struct mbuf *m, *n = (ifq)->ifq_drv_head; \
while((m = n) != NULL) { \
n = m->m_nextpkt; \
m_freem(m); \
} \
(ifq)->ifq_drv_head = (ifq)->ifq_drv_tail = NULL; \
(ifq)->ifq_drv_len = 0; \
IFQ_PURGE(ifq); \
} while (0)
static __inline int
drbr_enqueue(struct ifnet *ifp, struct buf_ring *br, struct mbuf *m)
{
int error = 0;
#ifdef ALTQ
if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
IFQ_ENQUEUE(&ifp->if_snd, m, error);
if (error)
if_inc_counter((ifp), IFCOUNTER_OQDROPS, 1);
return (error);
}
#endif
error = buf_ring_enqueue(br, m);
if (error)
m_freem(m);
return (error);
}
static __inline void
drbr_putback(struct ifnet *ifp, struct buf_ring *br, struct mbuf *new)
{
/*
* The top of the list needs to be swapped
* for this one.
*/
#ifdef ALTQ
if (ifp != NULL && ALTQ_IS_ENABLED(&ifp->if_snd)) {
/*
* Peek in altq case dequeued it
* so put it back.
*/
IFQ_DRV_PREPEND(&ifp->if_snd, new);
return;
}
#endif
buf_ring_putback_sc(br, new);
}
static __inline struct mbuf *
drbr_peek(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
struct mbuf *m;
if (ifp != NULL && ALTQ_IS_ENABLED(&ifp->if_snd)) {
/*
* Pull it off like a dequeue
* since drbr_advance() does nothing
* for altq and drbr_putback() will
* use the old prepend function.
*/
IFQ_DEQUEUE(&ifp->if_snd, m);
return (m);
}
#endif
return(buf_ring_peek_clear_sc(br));
}
static __inline void
drbr_flush(struct ifnet *ifp, struct buf_ring *br)
{
struct mbuf *m;
#ifdef ALTQ
if (ifp != NULL && ALTQ_IS_ENABLED(&ifp->if_snd))
IFQ_PURGE(&ifp->if_snd);
#endif
while ((m = buf_ring_dequeue_sc(br)) != NULL)
m_freem(m);
}
static __inline void
drbr_free(struct buf_ring *br, struct malloc_type *type)
{
drbr_flush(NULL, br);
buf_ring_free(br, type);
}
static __inline struct mbuf *
drbr_dequeue(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
struct mbuf *m;
if (ifp != NULL && ALTQ_IS_ENABLED(&ifp->if_snd)) {
IFQ_DEQUEUE(&ifp->if_snd, m);
return (m);
}
#endif
return (buf_ring_dequeue_sc(br));
}
static __inline void
drbr_advance(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
/* Nothing to do here since peek dequeues in altq case */
if (ifp != NULL && ALTQ_IS_ENABLED(&ifp->if_snd))
return;
#endif
return (buf_ring_advance_sc(br));
}
static __inline struct mbuf *
drbr_dequeue_cond(struct ifnet *ifp, struct buf_ring *br,
int (*func) (struct mbuf *, void *), void *arg)
{
struct mbuf *m;
#ifdef ALTQ
if (ALTQ_IS_ENABLED(&ifp->if_snd)) {
IFQ_LOCK(&ifp->if_snd);
IFQ_POLL_NOLOCK(&ifp->if_snd, m);
if (m != NULL && func(m, arg) == 0) {
IFQ_UNLOCK(&ifp->if_snd);
return (NULL);
}
IFQ_DEQUEUE_NOLOCK(&ifp->if_snd, m);
IFQ_UNLOCK(&ifp->if_snd);
return (m);
}
#endif
m = buf_ring_peek(br);
if (m == NULL || func(m, arg) == 0)
return (NULL);
return (buf_ring_dequeue_sc(br));
}
static __inline int
drbr_empty(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
if (ALTQ_IS_ENABLED(&ifp->if_snd))
return (IFQ_IS_EMPTY(&ifp->if_snd));
#endif
return (buf_ring_empty(br));
}
static __inline int
drbr_needs_enqueue(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
if (ALTQ_IS_ENABLED(&ifp->if_snd))
return (1);
#endif
return (!buf_ring_empty(br));
}
static __inline int
drbr_inuse(struct ifnet *ifp, struct buf_ring *br)
{
#ifdef ALTQ
if (ALTQ_IS_ENABLED(&ifp->if_snd))
return (ifp->if_snd.ifq_len);
#endif
return (buf_ring_count(br));
}
extern int ifqmaxlen;
void if_qflush(struct ifnet *);
void ifq_init(struct ifaltq *, struct ifnet *ifp);
void ifq_delete(struct ifaltq *);
#endif /* _KERNEL */
#endif /* !_NET_IFQ_H_ */
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