Re: [PATCH] devtmpfs: Add missing lockdep annotation

From: Greg Kroah-Hartman
Date: Sat Aug 12 2023 - 07:11:25 EST


On Fri, Aug 11, 2023 at 06:02:29PM +0200, Helge Deller wrote:
> Add the lockdep annotation to the setup_done completer to avoid this
> kernel warning:
>
> Backtrace:
> [<000000004030bcd0>] show_stack+0x74/0xb0
> [<000000004146c63c>] dump_stack_lvl+0x104/0x180
> [<000000004146c6ec>] dump_stack+0x34/0x48
> [<000000004040e5b4>] register_lock_class+0xd24/0xd30
> [<000000004040c21c>] __lock_acquire.isra.0+0xb4/0xac8
> [<000000004040cd60>] lock_acquire+0x130/0x298
> [<000000004147095c>] _raw_spin_lock_irq+0x60/0xb8
> [<0000000041474a4c>] wait_for_completion+0xa0/0x2d0
> [<000000004015d9f4>] devtmpfs_init+0x1e0/0x2b8
> [<000000004015d0e4>] driver_init+0x68/0x1b8
> [<0000000040102b68>] kernel_init_freeable+0x4ac/0x7f0
> [<000000004146df68>] kernel_init+0x64/0x3a8
> [<0000000040302020>] ret_from_kernel_thread+0x20/0x28
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
>
> diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
> index b848764ef018..f98d58b0225c 100644
> --- a/drivers/base/devtmpfs.c
> +++ b/drivers/base/devtmpfs.c
> @@ -462,6 +462,7 @@ int __init devtmpfs_init(void)
> return err;
> }
>
> + init_completion(&setup_done);
> thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
> if (!IS_ERR(thread)) {
> wait_for_completion(&setup_done);

What changed to required this now? What commit id does this fix? Why
doesn't the declaration of DECLARE_COMPLETION() initialize this properly
for us already?

thanks,

greg k-h