Author: melifaro
Date: Fri Apr  6 06:53:58 2012
New Revision: 233937
URL: http://svn.freebsd.org/changeset/base/233937

Log:
  - Improve BPF locking model.
  
  Interface locks and descriptor locks are converted from mutex(9) to rwlock(9).
  This greately improves performance: in most common case we need to acquire 1
  reader lock instead of 2 mutexes.
  
  - Remove filter(descriptor) (reader) lock in bpf_mtap[2]
  This was suggested by glebius@. We protect filter by requesting interface
  writer lock on filter change.
  
  - Cover struct bpf_if under BPF_INTERNAL define. This permits including bpf.h
  without including rwlock stuff. However, this is is temporary solution,
  struct bpf_if should be made opaque for any external caller.
  
  Found by:       Dmitrij Tejblum <tejb...@yandex-team.ru>
  Sponsored by:   Yandex LLC
  
  Reviewed by:    glebius (previous version)
  Reviewed by:    silence on -net@
  Approved by:    (mentor)
  
  MFC after:      3 weeks

Modified:
  head/sys/kern/subr_witness.c
  head/sys/net/bpf.c
  head/sys/net/bpf.h
  head/sys/net/bpf_buffer.c
  head/sys/net/bpf_zerocopy.c
  head/sys/net/bpfdesc.h
  head/sys/security/mac/mac_net.c

Modified: head/sys/kern/subr_witness.c
==============================================================================
--- head/sys/kern/subr_witness.c        Fri Apr  6 06:40:17 2012        
(r233936)
+++ head/sys/kern/subr_witness.c        Fri Apr  6 06:53:58 2012        
(r233937)
@@ -563,8 +563,8 @@ static struct witness_order_list_entry o
         * BPF
         */
        { "bpf global lock", &lock_class_mtx_sleep },
-       { "bpf interface lock", &lock_class_mtx_sleep },
-       { "bpf cdev lock", &lock_class_mtx_sleep },
+       { "bpf interface lock", &lock_class_rw },
+       { "bpf cdev lock", &lock_class_rw },
        { NULL, NULL },
        /*
         * NFS server

Modified: head/sys/net/bpf.c
==============================================================================
--- head/sys/net/bpf.c  Fri Apr  6 06:40:17 2012        (r233936)
+++ head/sys/net/bpf.c  Fri Apr  6 06:53:58 2012        (r233937)
@@ -43,6 +43,8 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/param.h>
+#include <sys/lock.h>
+#include <sys/rwlock.h>
 #include <sys/systm.h>
 #include <sys/conf.h>
 #include <sys/fcntl.h>
@@ -66,6 +68,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/socket.h>
 
 #include <net/if.h>
+#define        BPF_INTERNAL
 #include <net/bpf.h>
 #include <net/bpf_buffer.h>
 #ifdef BPF_JITTER
@@ -207,7 +210,7 @@ bpf_append_bytes(struct bpf_d *d, caddr_
     u_int len)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
@@ -227,7 +230,7 @@ bpf_append_mbuf(struct bpf_d *d, caddr_t
     u_int len)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
@@ -249,7 +252,7 @@ static void
 bpf_buf_reclaimed(struct bpf_d *d)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_BUFFER:
@@ -290,7 +293,6 @@ bpf_canfreebuf(struct bpf_d *d)
 static int
 bpf_canwritebuf(struct bpf_d *d)
 {
-
        BPFD_LOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
@@ -309,7 +311,7 @@ static void
 bpf_buffull(struct bpf_d *d)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
@@ -325,7 +327,7 @@ void
 bpf_bufheld(struct bpf_d *d)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        switch (d->bd_bufmode) {
        case BPF_BUFMODE_ZBUF:
@@ -574,12 +576,12 @@ bpf_attachd(struct bpf_d *d, struct bpf_
         * Finally, point the driver's bpf cookie at the interface so
         * it will divert packets to bpf.
         */
-       BPFIF_LOCK(bp);
+       BPFIF_WLOCK(bp);
        d->bd_bif = bp;
        LIST_INSERT_HEAD(&bp->bif_dlist, d, bd_next);
 
        bpf_bpfd_cnt++;
-       BPFIF_UNLOCK(bp);
+       BPFIF_WUNLOCK(bp);
 
        EVENTHANDLER_INVOKE(bpf_track, bp->bif_ifp, bp->bif_dlt, 1);
 }
@@ -594,20 +596,24 @@ bpf_detachd(struct bpf_d *d)
        struct bpf_if *bp;
        struct ifnet *ifp;
 
+       BPF_LOCK_ASSERT();
+
        bp = d->bd_bif;
-       BPFIF_LOCK(bp);
-       BPFD_LOCK(d);
-       ifp = d->bd_bif->bif_ifp;
+       BPFIF_WLOCK(bp);
+       BPFD_WLOCK(d);
 
        /*
         * Remove d from the interface's descriptor list.
         */
        LIST_REMOVE(d, bd_next);
 
-       bpf_bpfd_cnt--;
+       ifp = bp->bif_ifp;
        d->bd_bif = NULL;
-       BPFD_UNLOCK(d);
-       BPFIF_UNLOCK(bp);
+       BPFD_WUNLOCK(d);
+       BPFIF_WUNLOCK(bp);
+
+       /* We're already protected by global lock. */
+       bpf_bpfd_cnt--;
 
        EVENTHANDLER_INVOKE(bpf_track, ifp, bp->bif_dlt, 0);
 
@@ -642,16 +648,16 @@ bpf_dtor(void *data)
 {
        struct bpf_d *d = data;
 
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        funsetown(&d->bd_sigio);
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        if (d->bd_bif)
                bpf_detachd(d);
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
 #ifdef MAC
        mac_bpfdesc_destroy(d);
 #endif /* MAC */
@@ -689,14 +695,14 @@ bpfopen(struct cdev *dev, int flags, int
        d->bd_bufmode = BPF_BUFMODE_BUFFER;
        d->bd_sig = SIGIO;
        d->bd_direction = BPF_D_INOUT;
-       d->bd_pid = td->td_proc->p_pid;
+       BPF_PID_REFRESH(d, td);
 #ifdef MAC
        mac_bpfdesc_init(d);
        mac_bpfdesc_create(td->td_ucred, d);
 #endif
-       mtx_init(&d->bd_mtx, devtoname(dev), "bpf cdev lock", MTX_DEF);
-       callout_init_mtx(&d->bd_callout, &d->bd_mtx, 0);
-       knlist_init_mtx(&d->bd_sel.si_note, &d->bd_mtx);
+       rw_init(&d->bd_lock, "bpf cdev lock");
+       callout_init_rw(&d->bd_callout, &d->bd_lock, 0);
+       knlist_init_rw_reader(&d->bd_sel.si_note, &d->bd_lock);
 
        return (0);
 }
@@ -725,10 +731,10 @@ bpfread(struct cdev *dev, struct uio *ui
 
        non_block = ((ioflag & O_NONBLOCK) != 0);
 
-       BPFD_LOCK(d);
-       d->bd_pid = curthread->td_proc->p_pid;
+       BPFD_WLOCK(d);
+       BPF_PID_REFRESH_CUR(d);
        if (d->bd_bufmode != BPF_BUFMODE_BUFFER) {
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                return (EOPNOTSUPP);
        }
        if (d->bd_state == BPF_WAITING)
@@ -764,18 +770,18 @@ bpfread(struct cdev *dev, struct uio *ui
                 * it before using it again.
                 */
                if (d->bd_bif == NULL) {
-                       BPFD_UNLOCK(d);
+                       BPFD_WUNLOCK(d);
                        return (ENXIO);
                }
 
                if (non_block) {
-                       BPFD_UNLOCK(d);
+                       BPFD_WUNLOCK(d);
                        return (EWOULDBLOCK);
                }
-               error = msleep(d, &d->bd_mtx, PRINET|PCATCH,
+               error = rw_sleep(d, &d->bd_lock, PRINET|PCATCH,
                     "bpf", d->bd_rtout);
                if (error == EINTR || error == ERESTART) {
-                       BPFD_UNLOCK(d);
+                       BPFD_WUNLOCK(d);
                        return (error);
                }
                if (error == EWOULDBLOCK) {
@@ -793,7 +799,7 @@ bpfread(struct cdev *dev, struct uio *ui
                                break;
 
                        if (d->bd_slen == 0) {
-                               BPFD_UNLOCK(d);
+                               BPFD_WUNLOCK(d);
                                return (0);
                        }
                        ROTATE_BUFFERS(d);
@@ -803,7 +809,7 @@ bpfread(struct cdev *dev, struct uio *ui
        /*
         * At this point, we know we have something in the hold slot.
         */
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
 
        /*
         * Move data from hold buffer into user space.
@@ -816,12 +822,12 @@ bpfread(struct cdev *dev, struct uio *ui
         */
        error = bpf_uiomove(d, d->bd_hbuf, d->bd_hlen, uio);
 
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        d->bd_fbuf = d->bd_hbuf;
        d->bd_hbuf = NULL;
        d->bd_hlen = 0;
        bpf_buf_reclaimed(d);
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
 
        return (error);
 }
@@ -833,7 +839,7 @@ static __inline void
 bpf_wakeup(struct bpf_d *d)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
        if (d->bd_state == BPF_WAITING) {
                callout_stop(&d->bd_callout);
                d->bd_state = BPF_IDLE;
@@ -851,7 +857,7 @@ bpf_timed_out(void *arg)
 {
        struct bpf_d *d = (struct bpf_d *)arg;
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        if (callout_pending(&d->bd_callout) || !callout_active(&d->bd_callout))
                return;
@@ -866,7 +872,7 @@ static int
 bpf_ready(struct bpf_d *d)
 {
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        if (!bpf_canfreebuf(d) && d->bd_hlen != 0)
                return (1);
@@ -889,7 +895,7 @@ bpfwrite(struct cdev *dev, struct uio *u
        if (error != 0)
                return (error);
 
-       d->bd_pid = curthread->td_proc->p_pid;
+       BPF_PID_REFRESH_CUR(d);
        d->bd_wcount++;
        if (d->bd_bif == NULL) {
                d->bd_wdcount++;
@@ -937,11 +943,11 @@ bpfwrite(struct cdev *dev, struct uio *u
 
        CURVNET_SET(ifp->if_vnet);
 #ifdef MAC
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        mac_bpfdesc_create_mbuf(d, m);
        if (mc != NULL)
                mac_bpfdesc_create_mbuf(d, mc);
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
 #endif
 
        error = (*ifp->if_output)(ifp, m, &dst, NULL);
@@ -970,7 +976,7 @@ static void
 reset_d(struct bpf_d *d)
 {
 
-       mtx_assert(&d->bd_mtx, MA_OWNED);
+       BPFD_WLOCK_ASSERT(d);
 
        if ((d->bd_hbuf != NULL) &&
            (d->bd_bufmode != BPF_BUFMODE_ZBUF || bpf_canfreebuf(d))) {
@@ -1037,12 +1043,12 @@ bpfioctl(struct cdev *dev, u_long cmd, c
        /*
         * Refresh PID associated with this descriptor.
         */
-       BPFD_LOCK(d);
-       d->bd_pid = td->td_proc->p_pid;
+       BPFD_WLOCK(d);
+       BPF_PID_REFRESH(d, td);
        if (d->bd_state == BPF_WAITING)
                callout_stop(&d->bd_callout);
        d->bd_state = BPF_IDLE;
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
 
        if (d->bd_locked == 1) {
                switch (cmd) {
@@ -1108,11 +1114,11 @@ bpfioctl(struct cdev *dev, u_long cmd, c
                {
                        int n;
 
-                       BPFD_LOCK(d);
+                       BPFD_WLOCK(d);
                        n = d->bd_slen;
                        if (d->bd_hbuf)
                                n += d->bd_hlen;
-                       BPFD_UNLOCK(d);
+                       BPFD_WUNLOCK(d);
 
                        *(int *)addr = n;
                        break;
@@ -1163,9 +1169,9 @@ bpfioctl(struct cdev *dev, u_long cmd, c
         * Flush read packet buffer.
         */
        case BIOCFLUSH:
-               BPFD_LOCK(d);
+               BPFD_WLOCK(d);
                reset_d(d);
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                break;
 
        /*
@@ -1488,15 +1494,15 @@ bpfioctl(struct cdev *dev, u_long cmd, c
                        return (EINVAL);
                }
 
-               BPFD_LOCK(d);
+               BPFD_WLOCK(d);
                if (d->bd_sbuf != NULL || d->bd_hbuf != NULL ||
                    d->bd_fbuf != NULL || d->bd_bif != NULL) {
-                       BPFD_UNLOCK(d);
+                       BPFD_WUNLOCK(d);
                        CURVNET_RESTORE();
                        return (EBUSY);
                }
                d->bd_bufmode = *(u_int *)addr;
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                break;
 
        case BIOCGETZMAX:
@@ -1556,7 +1562,12 @@ bpf_setf(struct bpf_d *d, struct bpf_pro
        if (fp->bf_insns == NULL) {
                if (fp->bf_len != 0)
                        return (EINVAL);
-               BPFD_LOCK(d);
+               /* 
+                * Protect filter change by interface lock, too.
+                * The same lock order is used by bpf_detachd().
+                */
+               BPFIF_WLOCK(d->bd_bif);
+               BPFD_WLOCK(d);
                if (wfilter)
                        d->bd_wfilter = NULL;
                else {
@@ -1567,7 +1578,8 @@ bpf_setf(struct bpf_d *d, struct bpf_pro
                        if (cmd == BIOCSETF)
                                reset_d(d);
                }
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
+               BPFIF_WUNLOCK(d->bd_bif);
                if (old != NULL)
                        free((caddr_t)old, M_BPF);
 #ifdef BPF_JITTER
@@ -1584,7 +1596,12 @@ bpf_setf(struct bpf_d *d, struct bpf_pro
        fcode = (struct bpf_insn *)malloc(size, M_BPF, M_WAITOK);
        if (copyin((caddr_t)fp->bf_insns, (caddr_t)fcode, size) == 0 &&
            bpf_validate(fcode, (int)flen)) {
-               BPFD_LOCK(d);
+               /* 
+                * Protect filter change by interface lock, too
+                * The same lock order is used by bpf_detachd().
+                */
+               BPFIF_WLOCK(d->bd_bif);
+               BPFD_WLOCK(d);
                if (wfilter)
                        d->bd_wfilter = fcode;
                else {
@@ -1595,7 +1612,8 @@ bpf_setf(struct bpf_d *d, struct bpf_pro
                        if (cmd == BIOCSETF)
                                reset_d(d);
                }
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
+               BPFIF_WUNLOCK(d->bd_bif);
                if (old != NULL)
                        free((caddr_t)old, M_BPF);
 #ifdef BPF_JITTER
@@ -1659,9 +1677,9 @@ bpf_setif(struct bpf_d *d, struct ifreq 
 
                bpf_attachd(d, bp);
        }
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        reset_d(d);
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        return (0);
 }
 
@@ -1685,8 +1703,8 @@ bpfpoll(struct cdev *dev, int events, st
         * Refresh PID associated with this descriptor.
         */
        revents = events & (POLLOUT | POLLWRNORM);
-       BPFD_LOCK(d);
-       d->bd_pid = td->td_proc->p_pid;
+       BPFD_WLOCK(d);
+       BPF_PID_REFRESH(d, td);
        if (events & (POLLIN | POLLRDNORM)) {
                if (bpf_ready(d))
                        revents |= events & (POLLIN | POLLRDNORM);
@@ -1700,7 +1718,7 @@ bpfpoll(struct cdev *dev, int events, st
                        }
                }
        }
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        return (revents);
 }
 
@@ -1720,12 +1738,12 @@ bpfkqfilter(struct cdev *dev, struct kno
        /*
         * Refresh PID associated with this descriptor.
         */
-       BPFD_LOCK(d);
-       d->bd_pid = curthread->td_proc->p_pid;
+       BPFD_WLOCK(d);
+       BPF_PID_REFRESH_CUR(d);
        kn->kn_fop = &bpfread_filtops;
        kn->kn_hook = d;
        knlist_add(&d->bd_sel.si_note, kn, 1);
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
 
        return (0);
 }
@@ -1744,7 +1762,7 @@ filt_bpfread(struct knote *kn, long hint
        struct bpf_d *d = (struct bpf_d *)kn->kn_hook;
        int ready;
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
        ready = bpf_ready(d);
        if (ready) {
                kn->kn_data = d->bd_slen;
@@ -1819,9 +1837,19 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, 
        int gottime;
 
        gottime = BPF_TSTAMP_NONE;
-       BPFIF_LOCK(bp);
+
+       BPFIF_RLOCK(bp);
+
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
-               BPFD_LOCK(d);
+               /*
+                * We are not using any locks for d here because:
+                * 1) any filter change is protected by interface
+                * write lock
+                * 2) destroying/detaching d is protected by interface
+                * write lock, too
+                */
+
+               /* XXX: Do not protect counter for the sake of performance. */
                ++d->bd_rcount;
                /*
                 * NB: We dont call BPF_CHECK_DIRECTION() here since there is no
@@ -1837,6 +1865,11 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, 
 #endif
                slen = bpf_filter(d->bd_rfilter, pkt, pktlen, pktlen);
                if (slen != 0) {
+                       /*
+                        * Filter matches. Let's to acquire write lock.
+                        */
+                       BPFD_WLOCK(d);
+
                        d->bd_fcount++;
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp, NULL);
@@ -1845,10 +1878,10 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, 
 #endif
                                catchpacket(d, pkt, pktlen, slen,
                                    bpf_append_bytes, &bt);
+                       BPFD_WUNLOCK(d);
                }
-               BPFD_UNLOCK(d);
        }
-       BPFIF_UNLOCK(bp);
+       BPFIF_RUNLOCK(bp);
 }
 
 #define        BPF_CHECK_DIRECTION(d, r, i)                            \
@@ -1857,6 +1890,7 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, 
 
 /*
  * Incoming linkage from device drivers, when packet is in an mbuf chain.
+ * Locking model is explained in bpf_tap().
  */
 void
 bpf_mtap(struct bpf_if *bp, struct mbuf *m)
@@ -1876,13 +1910,13 @@ bpf_mtap(struct bpf_if *bp, struct mbuf 
        }
 
        pktlen = m_length(m, NULL);
-
        gottime = BPF_TSTAMP_NONE;
-       BPFIF_LOCK(bp);
+
+       BPFIF_RLOCK(bp);
+
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (BPF_CHECK_DIRECTION(d, m->m_pkthdr.rcvif, bp->bif_ifp))
                        continue;
-               BPFD_LOCK(d);
                ++d->bd_rcount;
 #ifdef BPF_JITTER
                bf = bpf_jitter_enable != 0 ? d->bd_bfilter : NULL;
@@ -1893,6 +1927,8 @@ bpf_mtap(struct bpf_if *bp, struct mbuf 
 #endif
                slen = bpf_filter(d->bd_rfilter, (u_char *)m, pktlen, 0);
                if (slen != 0) {
+                       BPFD_WLOCK(d);
+
                        d->bd_fcount++;
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp, m);
@@ -1901,10 +1937,10 @@ bpf_mtap(struct bpf_if *bp, struct mbuf 
 #endif
                                catchpacket(d, (u_char *)m, pktlen, slen,
                                    bpf_append_mbuf, &bt);
+                       BPFD_WUNLOCK(d);
                }
-               BPFD_UNLOCK(d);
        }
-       BPFIF_UNLOCK(bp);
+       BPFIF_RUNLOCK(bp);
 }
 
 /*
@@ -1938,14 +1974,17 @@ bpf_mtap2(struct bpf_if *bp, void *data,
        pktlen += dlen;
 
        gottime = BPF_TSTAMP_NONE;
-       BPFIF_LOCK(bp);
+
+       BPFIF_RLOCK(bp);
+
        LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
                if (BPF_CHECK_DIRECTION(d, m->m_pkthdr.rcvif, bp->bif_ifp))
                        continue;
-               BPFD_LOCK(d);
                ++d->bd_rcount;
                slen = bpf_filter(d->bd_rfilter, (u_char *)&mb, pktlen, 0);
                if (slen != 0) {
+                       BPFD_WLOCK(d);
+
                        d->bd_fcount++;
                        if (gottime < bpf_ts_quality(d->bd_tstamp))
                                gottime = bpf_gettime(&bt, d->bd_tstamp, m);
@@ -1954,10 +1993,10 @@ bpf_mtap2(struct bpf_if *bp, void *data,
 #endif
                                catchpacket(d, (u_char *)&mb, pktlen, slen,
                                    bpf_append_mbuf, &bt);
+                       BPFD_WUNLOCK(d);
                }
-               BPFD_UNLOCK(d);
        }
-       BPFIF_UNLOCK(bp);
+       BPFIF_RUNLOCK(bp);
 }
 
 #undef BPF_CHECK_DIRECTION
@@ -2049,7 +2088,7 @@ catchpacket(struct bpf_d *d, u_char *pkt
        int do_timestamp;
        int tstype;
 
-       BPFD_LOCK_ASSERT(d);
+       BPFD_WLOCK_ASSERT(d);
 
        /*
         * Detect whether user space has released a buffer back to us, and if
@@ -2196,7 +2235,7 @@ bpf_freed(struct bpf_d *d)
        }
        if (d->bd_wfilter != NULL)
                free((caddr_t)d->bd_wfilter, M_BPF);
-       mtx_destroy(&d->bd_mtx);
+       rw_destroy(&d->bd_lock);
 }
 
 /*
@@ -2228,13 +2267,13 @@ bpfattach2(struct ifnet *ifp, u_int dlt,
        LIST_INIT(&bp->bif_dlist);
        bp->bif_ifp = ifp;
        bp->bif_dlt = dlt;
-       mtx_init(&bp->bif_mtx, "bpf interface lock", NULL, MTX_DEF);
+       rw_init(&bp->bif_lock, "bpf interface lock");
        KASSERT(*driverp == NULL, ("bpfattach2: driverp already initialized"));
        *driverp = bp;
 
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        LIST_INSERT_HEAD(&bpf_iflist, bp, bif_next);
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
 
        bp->bif_hdrlen = hdrlen;
 
@@ -2261,14 +2300,14 @@ bpfdetach(struct ifnet *ifp)
 
        /* Find all bpf_if struct's which reference ifp and detach them. */
        do {
-               mtx_lock(&bpf_mtx);
+               BPF_LOCK();
                LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                        if (ifp == bp->bif_ifp)
                                break;
                }
                if (bp != NULL)
                        LIST_REMOVE(bp, bif_next);
-               mtx_unlock(&bpf_mtx);
+               BPF_UNLOCK();
 
                if (bp != NULL) {
 #ifdef INVARIANTS
@@ -2276,11 +2315,11 @@ bpfdetach(struct ifnet *ifp)
 #endif
                        while ((d = LIST_FIRST(&bp->bif_dlist)) != NULL) {
                                bpf_detachd(d);
-                               BPFD_LOCK(d);
+                               BPFD_WLOCK(d);
                                bpf_wakeup(d);
-                               BPFD_UNLOCK(d);
+                               BPFD_WUNLOCK(d);
                        }
-                       mtx_destroy(&bp->bif_mtx);
+                       rw_destroy(&bp->bif_lock);
                        free(bp, M_BPF);
                }
        } while (bp != NULL);
@@ -2304,13 +2343,13 @@ bpf_getdltlist(struct bpf_d *d, struct b
        ifp = d->bd_bif->bif_ifp;
        n = 0;
        error = 0;
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                if (bp->bif_ifp != ifp)
                        continue;
                if (bfl->bfl_list != NULL) {
                        if (n >= bfl->bfl_len) {
-                               mtx_unlock(&bpf_mtx);
+                               BPF_UNLOCK();
                                return (ENOMEM);
                        }
                        error = copyout(&bp->bif_dlt,
@@ -2318,7 +2357,7 @@ bpf_getdltlist(struct bpf_d *d, struct b
                }
                n++;
        }
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
        bfl->bfl_len = n;
        return (error);
 }
@@ -2336,19 +2375,19 @@ bpf_setdlt(struct bpf_d *d, u_int dlt)
        if (d->bd_bif->bif_dlt == dlt)
                return (0);
        ifp = d->bd_bif->bif_ifp;
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
                if (bp->bif_ifp == ifp && bp->bif_dlt == dlt)
                        break;
        }
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
        if (bp != NULL) {
                opromisc = d->bd_promisc;
                bpf_detachd(d);
                bpf_attachd(d, bp);
-               BPFD_LOCK(d);
+               BPFD_WLOCK(d);
                reset_d(d);
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                if (opromisc) {
                        error = ifpromisc(bp->bif_ifp, 1);
                        if (error)
@@ -2386,22 +2425,22 @@ bpf_zero_counters(void)
        struct bpf_if *bp;
        struct bpf_d *bd;
 
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
-               BPFIF_LOCK(bp);
+               BPFIF_RLOCK(bp);
                LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
-                       BPFD_LOCK(bd);
+                       BPFD_WLOCK(bd);
                        bd->bd_rcount = 0;
                        bd->bd_dcount = 0;
                        bd->bd_fcount = 0;
                        bd->bd_wcount = 0;
                        bd->bd_wfcount = 0;
                        bd->bd_zcopy = 0;
-                       BPFD_UNLOCK(bd);
+                       BPFD_WUNLOCK(bd);
                }
-               BPFIF_UNLOCK(bp);
+               BPFIF_RUNLOCK(bp);
        }
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
 }
 
 static void
@@ -2472,24 +2511,24 @@ bpf_stats_sysctl(SYSCTL_HANDLER_ARGS)
        if (bpf_bpfd_cnt == 0)
                return (SYSCTL_OUT(req, 0, 0));
        xbdbuf = malloc(req->oldlen, M_BPF, M_WAITOK);
-       mtx_lock(&bpf_mtx);
+       BPF_LOCK();
        if (req->oldlen < (bpf_bpfd_cnt * sizeof(*xbd))) {
-               mtx_unlock(&bpf_mtx);
+               BPF_UNLOCK();
                free(xbdbuf, M_BPF);
                return (ENOMEM);
        }
        index = 0;
        LIST_FOREACH(bp, &bpf_iflist, bif_next) {
-               BPFIF_LOCK(bp);
+               BPFIF_RLOCK(bp);
                LIST_FOREACH(bd, &bp->bif_dlist, bd_next) {
                        xbd = &xbdbuf[index++];
-                       BPFD_LOCK(bd);
+                       BPFD_RLOCK(bd);
                        bpfstats_fill_xbpf(xbd, bd);
-                       BPFD_UNLOCK(bd);
+                       BPFD_RUNLOCK(bd);
                }
-               BPFIF_UNLOCK(bp);
+               BPFIF_RUNLOCK(bp);
        }
-       mtx_unlock(&bpf_mtx);
+       BPF_UNLOCK();
        error = SYSCTL_OUT(req, xbdbuf, index * sizeof(*xbd));
        free(xbdbuf, M_BPF);
        return (error);

Modified: head/sys/net/bpf.h
==============================================================================
--- head/sys/net/bpf.h  Fri Apr  6 06:40:17 2012        (r233936)
+++ head/sys/net/bpf.h  Fri Apr  6 06:53:58 2012        (r233937)
@@ -1092,14 +1092,19 @@ SYSCTL_DECL(_net_bpf);
 
 /*
  * Descriptor associated with each attached hardware interface.
+ * FIXME: this structure is exposed to external callers to speed up
+ * bpf_peers_present() call. However we cover all fields not needed by
+ * this function via BPF_INTERNAL define
  */
 struct bpf_if {
        LIST_ENTRY(bpf_if)      bif_next;       /* list of all interfaces */
        LIST_HEAD(, bpf_d)      bif_dlist;      /* descriptor list */
+#ifdef BPF_INTERNAL
        u_int bif_dlt;                          /* link layer type */
        u_int bif_hdrlen;               /* length of link header */
        struct ifnet *bif_ifp;          /* corresponding interface */
-       struct mtx      bif_mtx;        /* mutex for interface */
+       struct rwlock bif_lock;         /* interface lock */
+#endif
 };
 
 void    bpf_bufheld(struct bpf_d *d);

Modified: head/sys/net/bpf_buffer.c
==============================================================================
--- head/sys/net/bpf_buffer.c   Fri Apr  6 06:40:17 2012        (r233936)
+++ head/sys/net/bpf_buffer.c   Fri Apr  6 06:53:58 2012        (r233937)
@@ -184,9 +184,9 @@ bpf_buffer_ioctl_sblen(struct bpf_d *d, 
 {
        u_int size;
 
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        if (d->bd_bif != NULL) {
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                return (EINVAL);
        }
        size = *i;
@@ -195,7 +195,7 @@ bpf_buffer_ioctl_sblen(struct bpf_d *d, 
        else if (size < BPF_MINBUFSIZE)
                *i = size = BPF_MINBUFSIZE;
        d->bd_bufsize = size;
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        return (0);
 }
 

Modified: head/sys/net/bpf_zerocopy.c
==============================================================================
--- head/sys/net/bpf_zerocopy.c Fri Apr  6 06:40:17 2012        (r233936)
+++ head/sys/net/bpf_zerocopy.c Fri Apr  6 06:53:58 2012        (r233937)
@@ -515,14 +515,14 @@ bpf_zerocopy_ioctl_rotzbuf(struct thread
        struct zbuf *bzh;
 
        bzero(bz, sizeof(*bz));
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        if (d->bd_hbuf == NULL && d->bd_slen != 0) {
                ROTATE_BUFFERS(d);
                bzh = (struct zbuf *)d->bd_hbuf;
                bz->bz_bufa = (void *)bzh->zb_uaddr;
                bz->bz_buflen = d->bd_hlen;
        }
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        return (0);
 }
 
@@ -570,10 +570,10 @@ bpf_zerocopy_ioctl_setzbuf(struct thread
         * We only allow buffers to be installed once, so atomically check
         * that no buffers are currently installed and install new buffers.
         */
-       BPFD_LOCK(d);
+       BPFD_WLOCK(d);
        if (d->bd_hbuf != NULL || d->bd_sbuf != NULL || d->bd_fbuf != NULL ||
            d->bd_bif != NULL) {
-               BPFD_UNLOCK(d);
+               BPFD_WUNLOCK(d);
                zbuf_free(zba);
                zbuf_free(zbb);
                return (EINVAL);
@@ -593,6 +593,6 @@ bpf_zerocopy_ioctl_setzbuf(struct thread
         * shared management region.
         */
        d->bd_bufsize = bz->bz_buflen - sizeof(struct bpf_zbuf_header);
-       BPFD_UNLOCK(d);
+       BPFD_WUNLOCK(d);
        return (0);
 }

Modified: head/sys/net/bpfdesc.h
==============================================================================
--- head/sys/net/bpfdesc.h      Fri Apr  6 06:40:17 2012        (r233936)
+++ head/sys/net/bpfdesc.h      Fri Apr  6 06:53:58 2012        (r233937)
@@ -87,7 +87,7 @@ struct bpf_d {
        int             bd_sig;         /* signal to send upon packet reception 
*/
        struct sigio *  bd_sigio;       /* information for async I/O */
        struct selinfo  bd_sel;         /* bsd select info */
-       struct mtx      bd_mtx;         /* mutex for this descriptor */
+       struct rwlock   bd_lock;        /* per-descriptor lock */
        struct callout  bd_callout;     /* for BPF timeouts with select */
        struct label    *bd_label;      /* MAC label for descriptor */
        u_int64_t       bd_fcount;      /* number of packets which matched 
filter */
@@ -106,10 +106,19 @@ struct bpf_d {
 #define BPF_WAITING    1               /* waiting for read timeout in select */
 #define BPF_TIMED_OUT  2               /* read timeout has expired in select */
 
-#define BPFD_LOCK(bd)          mtx_lock(&(bd)->bd_mtx)
-#define BPFD_UNLOCK(bd)                mtx_unlock(&(bd)->bd_mtx)
-#define BPFD_LOCK_ASSERT(bd)   mtx_assert(&(bd)->bd_mtx, MA_OWNED)
+#define BPFD_RLOCK(bd)         rw_rlock(&(bd)->bd_lock)
+#define BPFD_RUNLOCK(bd)       rw_runlock(&(bd)->bd_lock)
+#define BPFD_WLOCK(bd)         rw_wlock(&(bd)->bd_lock)
+#define BPFD_WUNLOCK(bd)       rw_wunlock(&(bd)->bd_lock)
+#define BPFD_WLOCK_ASSERT(bd)  rw_assert(&(bd)->bd_lock, RA_WLOCKED)
+#define BPFD_LOCK_ASSERT(bd)   rw_assert(&(bd)->bd_lock, RA_LOCKED)
 
+#define BPF_PID_REFRESH(bd, td)        (bd)->bd_pid = (td)->td_proc->p_pid
+#define BPF_PID_REFRESH_CUR(bd)        (bd)->bd_pid = curthread->td_proc->p_pid
+
+#define BPF_LOCK()             mtx_lock(&bpf_mtx)
+#define BPF_UNLOCK()           mtx_unlock(&bpf_mtx)
+#define BPF_LOCK_ASSERT()      mtx_assert(&bpf_mtx, MA_OWNED)
 /*
  * External representation of the bpf descriptor
  */
@@ -144,7 +153,9 @@ struct xbpf_d {
        u_int64_t       bd_spare[4];
 };
 
-#define BPFIF_LOCK(bif)                mtx_lock(&(bif)->bif_mtx)
-#define BPFIF_UNLOCK(bif)      mtx_unlock(&(bif)->bif_mtx)
+#define BPFIF_RLOCK(bif)       rw_rlock(&(bif)->bif_lock)
+#define BPFIF_RUNLOCK(bif)     rw_runlock(&(bif)->bif_lock)
+#define BPFIF_WLOCK(bif)       rw_wlock(&(bif)->bif_lock)
+#define BPFIF_WUNLOCK(bif)     rw_wunlock(&(bif)->bif_lock)
 
 #endif

Modified: head/sys/security/mac/mac_net.c
==============================================================================
--- head/sys/security/mac/mac_net.c     Fri Apr  6 06:40:17 2012        
(r233936)
+++ head/sys/security/mac/mac_net.c     Fri Apr  6 06:53:58 2012        
(r233937)
@@ -319,6 +319,7 @@ mac_bpfdesc_create_mbuf(struct bpf_d *d,
 {
        struct label *label;
 
+       /* Assume reader lock is enough. */
        BPFD_LOCK_ASSERT(d);
 
        if (mac_policy_count == 0)
@@ -354,6 +355,7 @@ mac_bpfdesc_check_receive(struct bpf_d *
 {
        int error;
 
+       /* Assume reader lock is enough. */
        BPFD_LOCK_ASSERT(d);
 
        if (mac_policy_count == 0)
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