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Do not allocate the buffers at opening of the descriptor, because once

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the buffer is allocated we are committed to a particular buffer method
(BPF_BUFMODE_BUFFER in this case).

If we are using zero-copy buffers, the userland program must register its
buffers before set the interface.

If we are using kernel memory buffers, we can allocate the buffer at the
time that the interface is being set.

This fix allows the usage of BIOCSETBUFMODE after r235746.

Update the comments to reflect the recent changes.

MFC after:	2 weeks
Sponsored by:	Rubicon Communications (Netgate)
This commit is contained in:
Luiz Otavio O Souza 2015-07-31 20:02:12 +00:00
parent 2deb37542b
commit 4f42daa4a3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=286139
1 changed files with 30 additions and 13 deletions
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43
sys/net/bpf.c
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@ -862,7 +862,7 @@ static int
bpfopen(struct cdev *dev, int flags, int fmt, struct thread *td)
{
struct bpf_d *d;
int error, size;
int error;
d = malloc(sizeof(*d), M_BPF, M_WAITOK | M_ZERO);
error = devfs_set_cdevpriv(d, bpf_dtor);
@ -892,10 +892,6 @@ bpfopen(struct cdev *dev, int flags, int fmt, struct thread *td)
callout_init_mtx(&d->bd_callout, &d->bd_lock, 0);
knlist_init_mtx(&d->bd_sel.si_note, &d->bd_lock);
/* Allocate default buffers */
size = d->bd_bufsize;
bpf_buffer_ioctl_sblen(d, &size);
return (0);
}
@ -1472,10 +1468,33 @@ bpfioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
* Set interface.
*/
case BIOCSETIF:
BPF_LOCK();
error = bpf_setif(d, (struct ifreq *)addr);
BPF_UNLOCK();
break;
{
int alloc_buf, size;
/*
* Behavior here depends on the buffering model. If
* we're using kernel memory buffers, then we can
* allocate them here. If we're using zero-copy,
* then the user process must have registered buffers
* by the time we get here.
*/
alloc_buf = 0;
BPFD_LOCK(d);
if (d->bd_bufmode == BPF_BUFMODE_BUFFER &&
d->bd_sbuf == NULL)
alloc_buf = 1;
BPFD_UNLOCK(d);
if (alloc_buf) {
size = d->bd_bufsize;
error = bpf_buffer_ioctl_sblen(d, &size);
if (error != 0)
break;
}
BPF_LOCK();
error = bpf_setif(d, (struct ifreq *)addr);
BPF_UNLOCK();
break;
}
/*
* Set read timeout.
@ -1912,10 +1931,8 @@ bpf_setif(struct bpf_d *d, struct ifreq *ifr)
BPFIF_RUNLOCK(bp);
/*
* Behavior here depends on the buffering model. If we're using
* kernel memory buffers, then we can allocate them here. If we're
* using zero-copy, then the user process must have registered
* buffers by the time we get here. If not, return an error.
* At this point, we expect the buffer is already allocated. If not,
* return an error.
*/
switch (d->bd_bufmode) {
case BPF_BUFMODE_BUFFER: