[PATCH v2 -next] arch_topology: Provide a stub topology_core_has_smt() for !CONFIG_GENERIC_ARCH_TOPOLOGY

[Yicong Yang]

The arm_pmu driver is using topology_core_has_smt() for retrieving
the SMT implementation which depends on CONFIG_GENERIC_ARCH_TOPOLOGY.
The config is optional on arm platforms so provide a
!CONFIG_GENERIC_ARCH_TOPOLOGY stub for topology_core_has_smt().

Fixes: c3d78c34ad00 ("perf: arm_pmuv3: Don't use PMCCNTR_EL0 on SMT cores")
Reported-by: kernel test robot <lkp at intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511041757.vuCGOmFc-lkp@intel.com/
Suggested-by: Will Deacon <will at kernel.org>
Signed-off-by: Yicong Yang <yangyccccc at gmail.com>
---
Change since v1:
- use a stub rather than guard the user with #ifdef block.
Link: https://lore.kernel.org/all/20251104134004.6964-1-yangyccccc@gmail.com/

 include/linux/arch_topology.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index daa1af2e8204..0c2a8b846c20 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -100,6 +100,10 @@ static inline bool topology_core_has_smt(int cpu)
 	return cpu_topology[cpu].thread_id != -1;
 }
 
-#endif
+#else
+
+static inline bool topology_core_has_smt(int cpu) { return false; }
+
+#endif /* CONFIG_GENERIC_ARCH_TOPOLOGY */
 
 #endif /* _LINUX_ARCH_TOPOLOGY_H_ */
-- 
2.50.1 (Apple Git-155)