Re: [PATCH v2 04/27] locking/atomic: make atomic*_{cmp,}xchg optional

[Guenter Roeck]

Hi,

On Mon, Jun 05, 2023 at 08:01:01AM +0100, Mark Rutland wrote:
> Most architectures define the atomic/atomic64 xchg and cmpxchg
> operations in terms of arch_xchg and arch_cmpxchg respectfully.
> 
> Add fallbacks for these cases and remove the trivial cases from arch
> code. On some architectures the existing definitions are kept as these
> are used to build other arch_atomic*() operations.
> 
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>

This patch results in:

ERROR: modpost: "__xchg_called_with_bad_pointer" [lib/atomic64_test.ko] undefined!

when trying to build sparc64:allmodconfig.

Guenter

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# first bad commit: [d12157efc8e083c77d054675fcdd594f54cc7e2b] locking/atomic: make atomic*_{cmp,}xchg optional