diff options
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/kern/uipc_mbuf.c | 8 | ||||
| -rw-r--r-- | sys/sys/mbuf.h | 9 |
2 files changed, 16 insertions, 1 deletions
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c index 98ec889..8e278a4 100644 --- a/sys/kern/uipc_mbuf.c +++ b/sys/kern/uipc_mbuf.c @@ -85,6 +85,14 @@ SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW, #endif /* + * Ensure the correct size of various mbuf parameters. It could be off due + * to compiler-induced padding and alignment artifacts. + */ +CTASSERT(sizeof(struct mbuf) == MSIZE); +CTASSERT(MSIZE - offsetof(struct mbuf, m_dat) == MLEN); +CTASSERT(MSIZE - offsetof(struct mbuf, m_pktdat) == MHLEN); + +/* * m_get2() allocates minimum mbuf that would fit "size" argument. */ struct mbuf * diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h index ce19715..7e8f427 100644 --- a/sys/sys/mbuf.h +++ b/sys/sys/mbuf.h @@ -53,6 +53,10 @@ * externally and attach it to the mbuf in a way similar to that of mbuf * clusters. * + * NB: These calculation do not take actual compiler-induced alignment and + * padding inside the complete struct mbuf into account. Appropriate + * attention is required when changing members of struct mbuf. + * * MLEN is data length in a normal mbuf. * MHLEN is data length in an mbuf with pktheader. * MINCLSIZE is a smallest amount of data that should be put into cluster. @@ -84,7 +88,7 @@ struct mb_args { /* * Header present at the beginning of every mbuf. - * Size ILP32: 20 + * Size ILP32: 24 * LP64: 32 */ struct m_hdr { @@ -94,6 +98,9 @@ struct m_hdr { int32_t mh_len; /* amount of data in this mbuf */ uint32_t mh_type:8, /* type of data in this mbuf */ mh_flags:24; /* flags; see below */ +#if !defined(__LP64__) + uint32_t mh_pad; /* pad for 64bit alignment */ +#endif }; /* |
