linux-kernel - [PATCH v8 01/10] x86/topology: Add missing struct declaration and attribute dependency

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Message-Id: <20260107-rneri-wakeup-mailbox-v8-1-2f5b6785f2f5@linux.intel.com>
Date: Wed, 07 Jan 2026 13:44:37 -0800
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: x86@...nel.org, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Rob Herring <robh@...nel.org>, 
 "K. Y. Srinivasan" <kys@...rosoft.com>, 
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, 
 Dexuan Cui <decui@...rosoft.com>, Michael Kelley <mhklinux@...look.com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Saurabh Sengar <ssengar@...ux.microsoft.com>, 
 Chris Oo <cho@...rosoft.com>, "Kirill A. Shutemov" <kas@...nel.org>, 
 linux-hyperv@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ricardo Neri <ricardo.neri@...el.com>, kernel test robot <lkp@...el.com>, 
 Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Subject: [PATCH v8 01/10] x86/topology: Add missing struct declaration and
 attribute dependency

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@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511181954.UMxCeTV1-lkp@intel.com/
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511190008.AA0NTn3G-lkp@intel.com/
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
I independently found this issue when including asm/acpi.h to arch/x86/
hyperv/hv_vtl.c, which implicitly includes asm/topology.h but not asm/
processor.h nor linux/cache.h.
---
Changes in v8:
 - Added this patch.

Changes in v7:
 - N/A

Changes in v6:
 - N/A

Changes in v5:
 - N/A

Changes in v4:
 - N/A

Changes in v3:
 - N/A

Changes in v2:
 - N/A

Changes in v3:
 - N/A

Changes in v2:
 - N/A
---
 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 1fadf0cf520c..630521a03982 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;

-- 
2.43.0