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Clarify some comments, fix some types, and rename ZBUF_FLAG_IMMUTABLE to

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ZBUF_FLAG_ASSIGNED to make it clear why the buffer can't be written to:
it is assigned to userspace.
This commit is contained in:
Robert Watson 2009-03-07 10:21:37 +00:00
parent 6affafd098
commit 784cd896fc
1 changed files with 18 additions and 18 deletions
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36
sys/net/bpf_zerocopy.c
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@ -91,7 +91,7 @@ __FBSDID("$FreeBSD$");
* knows that the space is not available.
*/
struct zbuf {
vm_offset_t zb_uaddr; /* User address, may be stale. */
vm_offset_t zb_uaddr; /* User address at time of setup. */
size_t zb_size; /* Size of buffer, incl. header. */
u_int zb_numpages; /* Number of pages. */
int zb_flags; /* Flags on zbuf. */
@ -104,7 +104,7 @@ struct zbuf {
* buffer may remain in the store position as a result of the user process
* not yet having acknowledged the buffer in the hold position yet.
*/
#define ZBUF_FLAG_IMMUTABLE 0x00000001 /* Set when owned by user. */
#define ZBUF_FLAG_ASSIGNED 0x00000001 /* Set when owned by user. */
/*
* Release a page we've previously wired.
@ -262,8 +262,8 @@ bpf_zerocopy_append_bytes(struct bpf_d *d, caddr_t buf, u_int offset,
src_bytes = (u_char *)src;
zb = (struct zbuf *)buf;
KASSERT((zb->zb_flags & ZBUF_FLAG_IMMUTABLE) == 0,
("bpf_zerocopy_append_bytes: ZBUF_FLAG_IMMUTABLE"));
KASSERT((zb->zb_flags & ZBUF_FLAG_ASSIGNED) == 0,
("bpf_zerocopy_append_bytes: ZBUF_FLAG_ASSIGNED"));
/*
* Scatter-gather copy to user pages mapped into kernel address space
@ -314,8 +314,8 @@ bpf_zerocopy_append_mbuf(struct bpf_d *d, caddr_t buf, u_int offset,
m = (struct mbuf *)src;
zb = (struct zbuf *)buf;
KASSERT((zb->zb_flags & ZBUF_FLAG_IMMUTABLE) == 0,
("bpf_zerocopy_append_mbuf: ZBUF_FLAG_IMMUTABLE"));
KASSERT((zb->zb_flags & ZBUF_FLAG_ASSIGNED) == 0,
("bpf_zerocopy_append_mbuf: ZBUF_FLAG_ASSIGNED"));
/*
* Scatter gather both from an mbuf chain and to a user page set
@ -374,8 +374,8 @@ bpf_zerocopy_buffull(struct bpf_d *d)
zb = (struct zbuf *)d->bd_sbuf;
KASSERT(zb != NULL, ("bpf_zerocopy_buffull: zb == NULL"));
if ((zb->zb_flags & ZBUF_FLAG_IMMUTABLE) == 0) {
zb->zb_flags |= ZBUF_FLAG_IMMUTABLE;
if ((zb->zb_flags & ZBUF_FLAG_ASSIGNED) == 0) {
zb->zb_flags |= ZBUF_FLAG_ASSIGNED;
zb->zb_header->bzh_kernel_len = d->bd_slen;
atomic_add_rel_int(&zb->zb_header->bzh_kernel_gen, 1);
}
@ -384,9 +384,8 @@ bpf_zerocopy_buffull(struct bpf_d *d)
/*
* Notification from the BPF framework that a buffer has moved into the held
* slot on a descriptor. Zero-copy BPF will update the shared page to let
* the user process know and flag the buffer as immutable if it hasn't
* already been marked immutable due to filling while it was in the store
* position.
* the user process know and flag the buffer as assigned if it hasn't already
* been marked assigned due to filling while it was in the store position.
*
* Note: identical logic as in bpf_zerocopy_buffull(), except that we operate
* on bd_hbuf and bd_hlen.
@ -402,8 +401,8 @@ bpf_zerocopy_bufheld(struct bpf_d *d)
zb = (struct zbuf *)d->bd_hbuf;
KASSERT(zb != NULL, ("bpf_zerocopy_bufheld: zb == NULL"));
if ((zb->zb_flags & ZBUF_FLAG_IMMUTABLE) == 0) {
zb->zb_flags |= ZBUF_FLAG_IMMUTABLE;
if ((zb->zb_flags & ZBUF_FLAG_ASSIGNED) == 0) {
zb->zb_flags |= ZBUF_FLAG_ASSIGNED;
zb->zb_header->bzh_kernel_len = d->bd_hlen;
atomic_add_rel_int(&zb->zb_header->bzh_kernel_gen, 1);
}
@ -411,7 +410,8 @@ bpf_zerocopy_bufheld(struct bpf_d *d)
/*
* Notification from the BPF framework that the free buffer has been been
* re-assigned. This happens when the user ackknowledges the buffer.
* rotated out of the held position to the free position. This happens when
* the user acknowledges the held buffer.
*/
void
bpf_zerocopy_buf_reclaimed(struct bpf_d *d)
@ -422,9 +422,9 @@ bpf_zerocopy_buf_reclaimed(struct bpf_d *d)
("bpf_zerocopy_reclaim_buf: not in zbuf mode"));
KASSERT(d->bd_fbuf != NULL,
("bpf_zerocopy_buf_reclaimed: NULL free buff"));
("bpf_zerocopy_buf_reclaimed: NULL free buf"));
zb = (struct zbuf *)d->bd_fbuf;
zb->zb_flags &= ~ZBUF_FLAG_IMMUTABLE;
zb->zb_flags &= ~ZBUF_FLAG_ASSIGNED;
}
/*
@ -467,7 +467,7 @@ bpf_zerocopy_canwritebuf(struct bpf_d *d)
zb = (struct zbuf *)d->bd_sbuf;
KASSERT(zb != NULL, ("bpf_zerocopy_canwritebuf: bd_sbuf NULL"));
if (zb->zb_flags & ZBUF_FLAG_IMMUTABLE)
if (zb->zb_flags & ZBUF_FLAG_ASSIGNED)
return (0);
return (1);
}
@ -510,7 +510,7 @@ bpf_zerocopy_ioctl_getzmax(struct thread *td, struct bpf_d *d, size_t *i)
/*
* Ioctl to force rotation of the two buffers, if there's any data available.
* This can be used by user space to implement time outs when waiting for a
* This can be used by user space to implement timeouts when waiting for a
* buffer to fill.
*/
int