From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

[ Upstream commit bdf5eb306c4d07a3bfdd4e2ab8f2acc7ff824940 ]

The prototypes for get_topology_cpu_type_name() and
get_topology_cpu_type() take a pointer to struct cpuinfo_x86, but
asm/topology.h neither includes nor forward-declares the structure.
Including asm/topology.h, directly or indirectly, without including
asm/processor.h triggers a warning:

    ./arch/x86/include/asm/topology.h:159:47: error: ‘struct cpuinfo_x86’
    declared inside parameter list will not be visible outside of this
    definition or declaration [-Werror]
    159 | const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c);
        |                                               ^~~~~~~~~~~

Since only a pointer is needed, add a forward declaration of struct
cpuinfo_x86.

Additionally, sysctl_sched_itmt_enabled is declared in asm/topology.h with
the __read_mostly attribute, but the header does not include linux/cache.h.
This causes a build failure when including asm/topology.h but not linux/
cache.h:

     ./arch/x86/include/asm/topology.h:264:27: error: expected ‘=’, ‘,’,
     ‘;’, ‘asm’ or ‘__attribute__’ before ‘sysctl_sched_itmt_enabled’
     264 | extern bool __read_mostly sysctl_sched_itmt_enabled;
         |                           ^~~~~~~~~~~~~~~~~~~~~~~~~

Include the required header.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511181954.UMxCeTV1-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511190008.AA0NTn3G-lkp@intel.com/
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Dexuan Cui <dexuan@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

The background search finished: `git log --grep='missing struct
declaration'` only turned up an unrelated `drm/i915/perf` commit, and
nothing matched `attribute dependency`. That confirms the topology
header fix isn’t in this v6.18.44 tree yet, which matches the earlier
analysis — the buggy code is still present and the patch should be
backported.

**YES**

 arch/x86/include/asm/topology.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 21041898157a1..63489ec410320 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -156,6 +156,8 @@ extern unsigned int __max_threads_per_core;
 extern unsigned int __num_threads_per_package;
 extern unsigned int __num_cores_per_package;
 
+struct cpuinfo_x86;
+
 const char *get_topology_cpu_type_name(struct cpuinfo_x86 *c);
 enum x86_topology_cpu_type get_topology_cpu_type(struct cpuinfo_x86 *c);
 
@@ -259,6 +261,7 @@ extern bool x86_topology_update;
 
 #ifdef CONFIG_SCHED_MC_PRIO
 #include <asm/percpu.h>
+#include <linux/cache.h>
 
 DECLARE_PER_CPU_READ_MOSTLY(int, sched_core_priority);
 extern bool __read_mostly sysctl_sched_itmt_enabled;
-- 
2.53.0