Merge branch 'tcp-fix-dsack-bug-with-non-contiguous-ranges'

Eric Dumazet says:

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tcp: fix DSACK bug with non contiguous ranges

This series combines a fix from xin.guo and a new packetdrill test.
====================

Link: https://patch.msgid.link/20250626123420.1933835-1-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>