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Instead of caching the PID which opened the bpf descriptor, continuously

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refresh the PID which has the descriptor open. The PID is refreshed in various
operations like ioctl(2), kevent(2) or poll(2). This produces more accurate
information about current bpf consumers. While we are here remove the bd_pcomm
member of the bpf stats structure because now that we have an accurate PID we
can lookup the via the kern.proc.pid sysctl variable. This is the trick that
NetBSD decided to use to deal with this issue.

Special care needs to be taken when MFC'ing this change, as we have made a
change to the bpf stats structure. What will end up happening is we will leave
the pcomm structure but just mark it as being un-used. This way we keep the ABI
in tact.

MFC after:	1 month
Discussed with:	Rui Paulo < rpaulo at NetBSD dot org >
This commit is contained in:
Christian S.J. Peron 2005-09-05 23:08:04 +00:00
parent d536ff2edb
commit b75a24a075
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=149809
2 changed files with 12 additions and 4 deletions
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14
sys/net/bpf.c
View File

@ -390,7 +390,6 @@ bpfopen(dev, flags, fmt, td)
d->bd_sig = SIGIO;
d->bd_seesent = 1;
d->bd_pid = td->td_proc->p_pid;
strlcpy(d->bd_pcomm, td->td_proc->p_comm, MAXCOMLEN);
#ifdef MAC
mac_init_bpfdesc(d);
mac_create_bpfdesc(td->td_ucred, d);
@ -694,6 +693,10 @@ bpfioctl(dev, cmd, addr, flags, td)
struct bpf_d *d = dev->si_drv1;
int error = 0;
/*
* Refresh PID associated with this descriptor.
*/
d->bd_pid = td->td_proc->p_pid;
BPFD_LOCK(d);
if (d->bd_state == BPF_WAITING)
callout_stop(&d->bd_callout);
@ -1141,6 +1144,10 @@ bpfpoll(dev, events, td)
if (d->bd_bif == NULL)
return (ENXIO);
/*
* Refresh PID associated with this descriptor.
*/
d->bd_pid = td->td_proc->p_pid;
revents = events & (POLLOUT | POLLWRNORM);
BPFD_LOCK(d);
if (events & (POLLIN | POLLRDNORM)) {
@ -1174,6 +1181,10 @@ bpfkqfilter(dev, kn)
if (kn->kn_filter != EVFILT_READ)
return (1);
/*
* Refresh PID associated with this descriptor.
*/
d->bd_pid = curthread->td_proc->p_pid;
kn->kn_fop = &bpfread_filtops;
kn->kn_hook = d;
knlist_add(&d->bd_sel.si_note, kn, 0);
@ -1724,7 +1735,6 @@ bpfstats_fill_xbpf(struct xbpf_d *d, struct bpf_d *bd)
d->bd_pid = bd->bd_pid;
strlcpy(d->bd_ifname,
bd->bd_bif->bif_ifp->if_xname, IFNAMSIZ);
strlcpy(d->bd_pcomm, bd->bd_pcomm, MAXCOMLEN);
d->bd_locked = bd->bd_locked;
}

2
sys/net/bpfdesc.h
View File

@ -95,7 +95,6 @@ struct bpf_d {
struct label *bd_label; /* MAC label for descriptor */
u_long bd_fcount; /* number of packets which matched filter */
pid_t bd_pid; /* PID which created descriptor */
char bd_pcomm[MAXCOMLEN + 1];
int bd_locked; /* true if descriptor is locked */
};
@ -148,7 +147,6 @@ struct xbpf_d {
int bd_bufsize;
pid_t bd_pid;
char bd_ifname[IFNAMSIZ];
char bd_pcomm[MAXCOMLEN + 1];
int bd_locked;
};