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netinet*: replace IP6_EXTHDR_GET()

Description

netinet*: replace IP6_EXTHDR_GET()

In a few places we have IP6_EXTHDR_GET() left in upper layer protocols.
The IP6_EXTHDR_GET() macro might perform an m_pulldown() in case the data
fragment is not contiguous.

Convert these last remaining instances into m_pullup()s instead.
In CARP, for example, we will a few lines later call m_pullup() anyway,
the IPsec code coming from OpenBSD would otherwise have done the m_pullup()
and are copying the data a bit later anyway, so pulling it in seems no
better or worse.

Note: this leaves very few m_pulldown() cases behind in the tree and we
might want to consider removing them as well to make mbuf management
easier again on a path to variable size mbufs, especially given
m_pulldown() still has an issue not re-checking M_WRITEABLE().

Reviewed by: gallatin
MFC after: 8 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D22335

Details

Committed
bzNov 15 2019, 9:44 PM
Reviewer
gallatin
Differential Revision
D22335: netinet*: replace IP6_EXTHDR_GET()
Parents
rS354748: netinet6: Remove PULLDOWN_TESTs.
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