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xtensa: Emulate two-byte cmpxchg

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Xtensa has no two-byte atomic compare and swap, so the __cmpxchg()
switch lets case 2 fall through to __cmpxchg_called_with_bad_pointer(),
which is declared but never defined, so a two-byte cmpxchg() fails
at link time.

Route case 2 through the new cmpxchg_emu_u16(), which takes the
old and new values as unsigned long and narrows them itself, so
the call needs no extra casts.

Signed-off-by: Bradley Morgan <brads@mainlining.org>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Bradley Morgan 2026-10-05 12:07:00 +00:00 committed by Paul E. McKenney
parent 2213947c08
commit 558ccc91dd
1 changed files with 1 additions and 0 deletions
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1
arch/xtensa/include/asm/cmpxchg.h
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@ -76,6 +76,7 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
switch (size) {
case 1: return cmpxchg_emu_u8(ptr, old, new);
case 2: return cmpxchg_emu_u16(ptr, old, new);
case 4: return __cmpxchg_u32(ptr, old, new);
default: __cmpxchg_called_with_bad_pointer();
return old;