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Introduce m_get3()

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Introduce m_get3() which is similar to m_get2(), but can allocate up to
MJUM16BYTES bytes (m_get2() can only allocate up to MJUMPAGESIZE).

This simplifies the bpf improvement in f13da24715.

Suggested by:	glebius
Differential Revision:	https://reviews.freebsd.org/D31455
This commit is contained in:
Kristof Provost 2021-08-07 20:02:21 +02:00
parent 66fa12d8fb
commit a051ca72e2
4 changed files with 50 additions and 9 deletions
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11
share/man/man9/mbuf.9
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd April 8, 2021
.Dd August 8, 2021
.Dt MBUF 9
.Os
.\"
@ -73,6 +73,8 @@
.Ft struct mbuf *
.Fn m_get2 "int size" "int how" "short type" "int flags"
.Ft struct mbuf *
.Fn m_get3 "int size" "int how" "short type" "int flags"
.Ft struct mbuf *
.Fn m_getm "struct mbuf *orig" "int len" "int how" "short type"
.Ft struct mbuf *
.Fn m_getjcl "int how" "short type" "int flags" "int size"
@ -577,6 +579,13 @@ with enough space to hold specified amount of data.
If the size is is larger than
.Dv MJUMPAGESIZE , NULL
will be returned.
.It Fn m_get3 size how type flags
Allocate an
.Vt mbuf
with enough space to hold specified amount of data.
If the size is is larger than
.Dv MJUM16BYTES, NULL
will be returned.
.It Fn m_getm orig len how type
Allocate
.Fa len

38
sys/kern/kern_mbuf.c
View File

@ -1371,6 +1371,44 @@ m_get2(int size, int how, short type, int flags)
return (m);
}
/*
* m_get3() allocates minimum mbuf that would fit "size" argument.
* Unlike m_get2() it can allocate clusters up to MJUM16BYTES.
*/
struct mbuf *
m_get3(int size, int how, short type, int flags)
{
struct mb_args args;
struct mbuf *m, *n;
uma_zone_t zone;
if (size <= MJUMPAGESIZE)
return (m_get2(size, how, type, flags));
if (size > MJUM16BYTES)
return (NULL);
args.flags = flags;
args.type = type;
m = uma_zalloc_arg(zone_mbuf, &args, how);
if (m == NULL)
return (NULL);
if (size <= MJUM9BYTES)
zone = zone_jumbo9;
else
zone = zone_jumbo16;
n = uma_zalloc_arg(zone_jumbop, m, how);
if (n == NULL) {
m_free_raw(m);
return (NULL);
}
return (m);
}
/*
* m_getjcl() returns an mbuf with a cluster of the specified size attached.
* For size it takes MCLBYTES, MJUMPAGESIZE, MJUM9BYTES, MJUM16BYTES.

9
sys/net/bpf.c
View File

@ -644,14 +644,7 @@ bpf_movein(struct uio *uio, int linktype, struct ifnet *ifp, struct mbuf **mp,
return (EMSGSIZE);
/* Allocate a mbuf for our write, since m_get2 fails if len >= to MJUMPAGESIZE, use m_getjcl for bigger buffers */
if (len < MJUMPAGESIZE)
m = m_get2(len, M_WAITOK, MT_DATA, M_PKTHDR);
else if (len <= MJUM9BYTES)
m = m_getjcl(M_WAITOK, MT_DATA, M_PKTHDR, MJUM9BYTES);
else if (len <= MJUM16BYTES)
m = m_getjcl(M_WAITOK, MT_DATA, M_PKTHDR, MJUM16BYTES);
else
m = NULL;
m = m_get3(len, M_WAITOK, MT_DATA, M_PKTHDR);
if (m == NULL)
return (EIO);
m->m_pkthdr.len = m->m_len = len;

1
sys/sys/mbuf.h
View File

@ -829,6 +829,7 @@ struct mbuf *m_fragment(struct mbuf *, int, int);
void m_freem(struct mbuf *);
void m_free_raw(struct mbuf *);
struct mbuf *m_get2(int, int, short, int);
struct mbuf *m_get3(int, int, short, int);
struct mbuf *m_getjcl(int, short, int, int);
struct mbuf *m_getm2(struct mbuf *, int, int, short, int);
struct mbuf *m_getptr(struct mbuf *, int, int *);