Commit 622c508b authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

cpu: Provide lockdep check for CPU hotplug lock write-held 



cpuset modifies partitions, including isolated, while holding the cpu
hotplug lock read-held.

This means that write-holding the CPU hotplug lock is safe to
synchronize against housekeeping cpumask changes.

Provide a lockdep check to validate that.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Cc: Marco Crivellari <marco.crivellari@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: linux-kernel@vger.kernel.org
parent b5de34ed

include/linux/cpuhplock.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
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);

include/linux/percpu-rwsem.h

+1 −0
Original line number Diff line number Diff line
@@ -161,6 +161,7 @@ extern void percpu_free_rwsem(struct percpu_rw_semaphore *); 
	__percpu_init_rwsem(sem, #sem, &rwsem_key);		\

})



#define percpu_rwsem_is_write_held(sem)	lockdep_is_held_type(sem, 0)

#define percpu_rwsem_is_held(sem)	lockdep_is_held(sem)

#define percpu_rwsem_assert_held(sem)	lockdep_assert_held(sem)

kernel/cpu.c

+5 −0
Original line number Diff line number Diff line
@@ -534,6 +534,11 @@ int lockdep_is_cpus_held(void) 
{

	return percpu_rwsem_is_held(&cpu_hotplug_lock);

}



int lockdep_is_cpus_write_held(void)

{

	return percpu_rwsem_is_write_held(&cpu_hotplug_lock);

}

#endif



static void lockdep_acquire_cpus_lock(void)