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Rather than calling mircotime() in catchpacket(), make catchpacket()

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take a timeval indicating when the packet was captured. Move
microtime() to the calling functions and grab the timestamp as soon
as we know that we're going to call catchpacket at least once.

This means that we call microtime() once per matched packet, as
opposed to once per matched packet per bpf listener. It also means
that we return the same timestamp to all bpf listeners, rather than
slightly different ones.

It would be more accurate to call microtime() even earlier for all
packets, as you have to grab (1+#listener) locks before you can
determine if the packet will be logged. You could always grab a
timestamp before the locks, but microtime() can be costly, so this
didn't seem like a good idea.

(I guess most ethernet interfaces will have a bpf listener these
days because of dhclient. That means that we could be doing two bpf
locks on most packets going through the interface.)

PR:		71711
This commit is contained in:
David Malone 2006-07-24 15:42:04 +00:00
parent b0668f7151
commit 91433904b5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=160620
1 changed files with 30 additions and 6 deletions
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36
sys/net/bpf.c
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@ -103,7 +103,8 @@ static void bpf_timed_out(void *);
static __inline void
bpf_wakeup(struct bpf_d *);
static void catchpacket(struct bpf_d *, u_char *, u_int,
u_int, void (*)(const void *, void *, size_t));
u_int, void (*)(const void *, void *, size_t),
struct timeval *);
static void reset_d(struct bpf_d *);
static int bpf_setf(struct bpf_d *, struct bpf_program *, u_long cmd);
static int bpf_getdltlist(struct bpf_d *, struct bpf_dltlist *);
@ -1199,7 +1200,10 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
{
struct bpf_d *d;
u_int slen;
int gottime;
struct timeval tv;
gottime = 0;
BPFIF_LOCK(bp);
LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
BPFD_LOCK(d);
@ -1212,10 +1216,14 @@ bpf_tap(struct bpf_if *bp, u_char *pkt, u_int pktlen)
slen = bpf_filter(d->bd_rfilter, pkt, pktlen, pktlen);
if (slen != 0) {
d->bd_fcount++;
if (!gottime) {
microtime(&tv);
gottime = 1;
}
#ifdef MAC
if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
#endif
catchpacket(d, pkt, pktlen, slen, bcopy);
catchpacket(d, pkt, pktlen, slen, bcopy, &tv);
}
BPFD_UNLOCK(d);
}
@ -1254,6 +1262,10 @@ bpf_mtap(struct bpf_if *bp, struct mbuf *m)
{
struct bpf_d *d;
u_int pktlen, slen;
int gottime;
struct timeval tv;
gottime = 0;
pktlen = m_length(m, NULL);
@ -1274,11 +1286,15 @@ bpf_mtap(struct bpf_if *bp, struct mbuf *m)
slen = bpf_filter(d->bd_rfilter, (u_char *)m, pktlen, 0);
if (slen != 0) {
d->bd_fcount++;
if (!gottime) {
microtime(&tv);
gottime = 1;
}
#ifdef MAC
if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
#endif
catchpacket(d, (u_char *)m, pktlen, slen,
bpf_mcopy);
bpf_mcopy, &tv);
}
BPFD_UNLOCK(d);
}
@ -1295,6 +1311,10 @@ bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m)
struct mbuf mb;
struct bpf_d *d;
u_int pktlen, slen;
int gottime;
struct timeval tv;
gottime = 0;
pktlen = m_length(m, NULL);
/*
@ -1316,11 +1336,15 @@ bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m)
slen = bpf_filter(d->bd_rfilter, (u_char *)&mb, pktlen, 0);
if (slen != 0) {
d->bd_fcount++;
if (!gottime) {
microtime(&tv);
gottime = 1;
}
#ifdef MAC
if (mac_check_bpfdesc_receive(d, bp->bif_ifp) == 0)
#endif
catchpacket(d, (u_char *)&mb, pktlen, slen,
bpf_mcopy);
bpf_mcopy, &tv);
}
BPFD_UNLOCK(d);
}
@ -1336,7 +1360,7 @@ bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m)
*/
static void
catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
void (*cpfn)(const void *, void *, size_t))
void (*cpfn)(const void *, void *, size_t), struct timeval *tv)
{
struct bpf_hdr *hp;
int totlen, curlen;
@ -1388,7 +1412,7 @@ catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
* Append the bpf header.
*/
hp = (struct bpf_hdr *)(d->bd_sbuf + curlen);
microtime(&hp->bh_tstamp);
hp->bh_tstamp = *tv;
hp->bh_datalen = pktlen;
hp->bh_hdrlen = hdrlen;
/*