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Add a comment and KASSERT that a M_NOFREE mbuf has always EXT_EXTREF ext.

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Submitted by:	kmacy
This commit is contained in:
Gleb Smirnoff 2016-05-17 23:15:16 +00:00
parent f59d975e10
commit 17cd649f4a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=300097
1 changed files with 9 additions and 2 deletions
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11
sys/kern/kern_mbuf.c
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@ -638,9 +638,16 @@ mb_free_ext(struct mbuf *m)
* Check if the header is embedded in the cluster. It is
* important that we can't touch any of the mbuf fields
* after we have freed the external storage, since mbuf
* could have been embedded in it.
* could have been embedded in it. For now, the mbufs
* embedded into the cluster are always of type EXT_EXTREF,
* and for this type we won't free the mref.
*/
freembuf = (m->m_flags & M_NOFREE) ? 0 : 1;
if (m->m_flags & M_NOFREE) {
freembuf = 0;
KASSERT(m->m_ext.ext_type == EXT_EXTREF,
("%s: no-free mbuf %p has wrong type", __func__, m));
} else
freembuf = 1;
/* Free attached storage if this mbuf is the only reference to it. */
if (*refcnt == 1 || atomic_fetchadd_int(refcnt, -1) == 1) {