queue.h: Define {LIST,TAILQ}_REMOVE_HEAD
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Authored by cperciva on Jul 19 2023, 12:58 AM.

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jhb
emaste

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rG79fafc09740a: queue.h: Define {LIST,TAILQ}_REMOVE_HEAD

Summary

The LIST and TAILQ structures have fast _REMOVE macros (since each
element has a pointer to the previous element); we implement the
_REMOVE_HEAD macros for them by simply finding the first element and
then removing it.

Sponsored by: https://www.patreon.com/cperciva

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rG FreeBSD src repository

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Event Timeline

cperciva created this revision.Jul 19 2023, 12:58 AM

Herald added a subscriber: imp. · View Herald TranscriptJul 19 2023, 12:58 AM

cperciva requested review of this revision.Jul 19 2023, 12:58 AM

Harbormaster completed remote builds in B52696: Diff 124818.Jul 19 2023, 12:58 AM

cperciva added a child revision: D41073: Add <sys/queue_mergesort.h>.Jul 19 2023, 12:59 AM

I wonder why these were never implemented before.
FWIW I found one LIST_REMOVE(LIST_FIRST... in the tree, in sys/dev/neta/if_mvneta.c

In D41072#935530, @emaste wrote:

I wonder why these were never implemented before.

Probably because _REMOVE was considered the "first class citizen" and _REMOVE_HEAD was only provided as an alternative for list types which didn't have _REMOVE.