On Mon, 29 Jan 2024, Warner Losh wrote:
The branch main has been updated by imp:
URL:
https://cgit.FreeBSD.org/src/commit/?id=3be59adbb5a2ae7600d46432d3bc82286e507e95
commit 3be59adbb5a2ae7600d46432d3bc82286e507e95
Author: Warner Losh <[email protected]>
AuthorDate: 2024-01-29 05:08:55 +0000
Commit: Warner Losh <[email protected]>
CommitDate: 2024-01-29 05:08:55 +0000
vtnet: Adjust for ethernet alignment.
If the header that we add to the packet's size is 0 % 4 and we're
strictly aligning, then we need to adjust where we store the header so
the packet that follows will have it's struct ip header properly
aligned. We do this on allocation (and when we check the length of the
mbufs in the lro_nomrg case). We can't just adjust the clustersz in the
softc, because it's also used to allocate the mbufs and it needs to be
the proper size for that. Since we otherwise use the size of the mbuf
(or sometimes the smaller size of the received packet) to compute how
much we can buffer, this ensures no overflows. The 2 byte adjustment
also does not affect how many packets we can receive in the lro_nomrg
case.
Doesn't this still include at least these two un-asserted/un-documented
asumptions:
(a) mbuf space is large enough to hold 2 extra bytes? Is this always
the case?
(b) the struct sizes assigned to vtnet_hdr_size are not odd numbers of
bytes? Could add comments or CTASSERTs?
PR: 271288
Sponsored by: Netflix
Reviewed by: bryanv
Differential Revision: https://reviews.freebsd.org/D43224
--
Bjoern A. Zeeb r15:7
