CVS commit: src/sys/arch/mips

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Feb 27 19:22:03 UTC 2022

Modified Files:
        src/sys/arch/mips/include: asm.h
        src/sys/arch/mips/mips: lock_stubs_llsc.S

Log Message:
mips: Omit needless SYNC in mutex_exit.

This change deletes a memory barrier.  However, it should be safe:
The semantic requirement for this is already provided by the SYNC_REL
above, before the ll.  And as currently defined, SYNC_REL is at least
as strong as SYNC, so this change can't hurt correctness on its own
(barring CPU errata, which would apply to other users of SYNC_REL and
can be addressed in the definition of SYNC_REL).

Later, perhaps we can relax SYNC_REL to syncw on Octeon if we prove
that it is correct (e.g., if Octeon follows the SPARCv9 partial store
order semantics).

Nix now-unused SYNC macro in asm.h.


To generate a diff of this commit:
cvs rdiff -u -r1.66 -r1.67 src/sys/arch/mips/include/asm.h
cvs rdiff -u -r1.15 -r1.16 src/sys/arch/mips/mips/lock_stubs_llsc.S

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.