The following commit has been merged into the smp/core branch of tip:

Commit-ID:     9c91efd1d63e995bb0577fc1c5e909613dfe671d
Gitweb:        https://git.kernel.org/tip/9c91efd1d63e995bb0577fc1c5e909613dfe671d
Author:        Reinette Chatre <reinette.chatre@intel.com>
AuthorDate:    Wed, 03 Jun 2026 20:38:47 -07:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Thu, 04 Jun 2026 10:55:27 +02:00

cpu: Add lockdep_is_cpus_held()/lockdep_is_cpus_write_held() stubs for !CONFIG_HOTPLUG_CPU

lockdep_is_cpus_held() and lockdep_is_cpus_write_held() are undefined when
!CONFIG_HOTPLUG_CPU. This is ok because their few callers protect the calls
with a "if (IS_ENABLED(CONFIG_HOTPLUG_CPU) ..." check.

It is error prone to require callers to protect lockdep_is_cpus_held()
and lockdep_is_cpus_write_held() with an IS_ENABLED(CONFIG_HOTPLUG_CPU)
check while the custom for equivalent functions, for example the more
prevalent lockdep_is_held(), is to not require similar protection.
It is also inconsistent with CPU hotplug lockdep code self since related
call lockdep_assert_cpus_held() does not require protection.

Create stubs for lockdep_is_cpus_held() and lockdep_is_cpus_write_held()
that returns 1 (LOCK_STATE_UNKNOWN/LOCK_STATE_HELD) when !CONFIG_HOTPLUG_CPU.
This makes the CPU hotplug lockdep checks consistent while following
existing lockdep custom. Drop the "extern" from the function declaration
as part of the move to match kernel coding style.

Keep the IS_ENABLED(CONFIG_HOTPLUG_CPU) checks in existing users since
removing them would change the logic of these expressions.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/7484f0b58fd86153d445819cc4e172adba16cff9.1780543665.git.reinette.chatre@intel.com
Closes: https://sashiko.dev/#/patchset/cover.1780456704.git.reinette.chatre%40intel.com?part=1
---
 include/linux/cpuhplock.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/cpuhplock.h b/include/linux/cpuhplock.h
index 286b3ab..42f6a09 100644
--- a/include/linux/cpuhplock.h
+++ b/include/linux/cpuhplock.h
@@ -12,9 +12,6 @@
 
 struct device;
 
-extern int lockdep_is_cpus_held(void);
-extern int lockdep_is_cpus_write_held(void);
-
 #ifdef CONFIG_HOTPLUG_CPU
 void cpus_write_lock(void);
 void cpus_write_unlock(void);
@@ -22,6 +19,8 @@ void cpus_read_lock(void);
 void cpus_read_unlock(void);
 int  cpus_read_trylock(void);
 void lockdep_assert_cpus_held(void);
+int lockdep_is_cpus_held(void);
+int lockdep_is_cpus_write_held(void);
 void cpu_hotplug_disable_offlining(void);
 void cpu_hotplug_disable(void);
 void cpu_hotplug_enable(void);
@@ -38,6 +37,8 @@ static inline void cpus_read_lock(void) { }
 static inline void cpus_read_unlock(void) { }
 static inline int  cpus_read_trylock(void) { return true; }
 static inline void lockdep_assert_cpus_held(void) { }
+static inline int lockdep_is_cpus_held(void) { return 1; }
+static inline int lockdep_is_cpus_write_held(void) { return 1; }
 static inline void cpu_hotplug_disable_offlining(void) { }
 static inline void cpu_hotplug_disable(void) { }
 static inline void cpu_hotplug_enable(void) { }