Re: [PATCH v2 17/24] x86/cpu: Make sure play_dead() doesn't return

[Philippe Mathieu-Daudé]

On 14/2/23 08:05, Josh Poimboeuf wrote:

After commit 076cbf5d2163 ("x86/xen: don't let xen_pv_play_dead()
return"), play_dead() never returns.  Make that more explicit with a
BUG().

BUG() is preferable to unreachable() because BUG() is a more explicit
failure mode and avoids undefined behavior like falling off the edge of
the function into whatever code happens to be next.

Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
---
  arch/x86/include/asm/smp.h | 1 +
  1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index b4dbb20dab1a..8f628e08b25a 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -96,6 +96,7 @@ static inline void __cpu_die(unsigned int cpu)
  static inline void play_dead(void)
  {
        smp_ops.play_dead();
+       BUG();
  }

Similarly, smp_ops::play_dead() should be decorated noreturn first.