Commit-ID: f1b2f6eccf99fc457221cc84c7550a8e3b17d4df Gitweb: https://git.kernel.org/tip/f1b2f6eccf99fc457221cc84c7550a8e3b17d4df Author: Peter Zijlstra <[email protected]> AuthorDate: Tue, 11 Sep 2018 11:51:27 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 11 Sep 2018 12:37:00 +0200
locking/lockdep, cpu/hotplug: Annotate AP thread 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 <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Fixes: cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/cpu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index 0097acec1c71..08c168b159da 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -616,6 +616,12 @@ 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. + */ + rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_); cpuhp_lock_acquire(bringup); if (st->single) { @@ -661,6 +667,7 @@ static void cpuhp_thread_fun(unsigned int cpu) } cpuhp_lock_release(bringup); + rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_); if (!st->should_run) complete_ap_thread(st, bringup);
