locking/lockdep, cpu/hotplug: Annotate AP thread (cb92173d) · Commits · 戴 / test

Anybody trying to assert the cpu_hotplug_lock is held (lockdep_assert_cpus_held()) from AP callbacks will fail, because the lock is held by the BP. Stick in an explicit annotation in cpuhp_thread_fun() to make this work. Reported-by:

Ingo Molnar <mingo@kernel.org> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-tip-commits@vger.kernel.org Fixes: ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations") Link: http://lkml.kernel.org/r/20180911095127.GT24082@hirez.programming.kicks-ass.net Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/cpu.c

+28 −0

Original line number	Diff line number	Diff line
		@@ -315,6 +315,16 @@ void lockdep_assert_cpus_held(void)
		percpu_rwsem_assert_held(&cpu_hotplug_lock);
		}

		static void lockdep_acquire_cpus_lock(void)
		{
		rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
		}

		static void lockdep_release_cpus_lock(void)
		{
		rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_);
		}

		/*
		* Wait for currently running CPU hotplug operations to complete (if any) and
		* disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
		@@ -344,6 +354,17 @@ void cpu_hotplug_enable(void)
		cpu_maps_update_done();
		}
		EXPORT_SYMBOL_GPL(cpu_hotplug_enable);

		#else

		static void lockdep_acquire_cpus_lock(void)
		{
		}

		static void lockdep_release_cpus_lock(void)
		{
		}

		#endif /* CONFIG_HOTPLUG_CPU */

		#ifdef CONFIG_HOTPLUG_SMT
		@@ -616,6 +637,12 @@ static void cpuhp_thread_fun(unsigned int cpu)
		*/
		smp_mb();

		/*
		* The BP holds the hotplug lock, but we're now running on the AP,
		* ensure that anybody asserting the lock is held, will actually find
		* it so.
		*/
		lockdep_acquire_cpus_lock();
		cpuhp_lock_acquire(bringup);

		if (st->single) {
		@@ -661,6 +688,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
		}

		cpuhp_lock_release(bringup);
		lockdep_release_cpus_lock();

		if (!st->should_run)
		complete_ap_thread(st, bringup);

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