Subject: Re: [PATCH] powerpc/powermac: Add missing lockdep_register_key()

From: "Erhard F." <[email-masked]>
Date: Tue, 30 Nov 2021 14:53:18 +0100

On Tue, 30 Nov 2021 10:32:42 +0100
Christophe Leroy <[email-masked]> wrote:

> KeyWest i2c @0xf8001003 irq 42 /uni-n@f8000000/i2c@f8001000
> BUG: key c2d00cbc has not been registered!
> ------------[ cut here ]------------
> DEBUG_LOCKS_WARN_ON(1)
> WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:4801 lockdep_init_map_type+0x4c0/0xb4c
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.5-gentoo-PowerMacG4 #9
> NIP:  c01a9428 LR: c01a9428 CTR: 00000000
> REGS: e1033cf0 TRAP: 0700   Not tainted  (5.15.5-gentoo-PowerMacG4)
> MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 24002002  XER: 00000000
> 
> GPR00: c01a9428 e1033db0 c2d1cf20 00000016 00000004 00000001 c01c0630 e1033a73
> GPR08: 00000000 00000000 00000000 e1033db0 24002004 00000000 f8729377 00000003
> GPR16: c1829a9c 00000000 18305357 c1416fc0 c1416f80 c006ac60 c2d00ca8 c1416f00
> GPR24: 00000000 c21586f0 c2160000 00000000 c2d00cbc c2170000 c216e1a0 c2160000
> NIP [c01a9428] lockdep_init_map_type+0x4c0/0xb4c
> LR [c01a9428] lockdep_init_map_type+0x4c0/0xb4c
> Call Trace:
> [e1033db0] [c01a9428] lockdep_init_map_type+0x4c0/0xb4c (unreliable)
> [e1033df0] [c1c177b8] kw_i2c_add+0x334/0x424
> [e1033e20] [c1c18294] pmac_i2c_init+0x9ec/0xa9c
> [e1033e80] [c1c1a790] smp_core99_probe+0xbc/0x35c
> [e1033eb0] [c1c03cb0] kernel_init_freeable+0x190/0x5a4
> [e1033f10] [c000946c] kernel_init+0x28/0x154
> [e1033f30] [c0035148] ret_from_kernel_thread+0x14/0x1c
> 
> Add missing lockdep_register_key()
> 
> Reported-by: Erhard Furtner <[email-masked]>
> Signed-off-by: Christophe Leroy <[email-masked]>
> ---
>  arch/powerpc/platforms/powermac/low_i2c.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
> index f77a59b5c2e1..de34fa34c42d 100644
> --- a/arch/powerpc/platforms/powermac/low_i2c.c
> +++ b/arch/powerpc/platforms/powermac/low_i2c.c
> @@ -582,6 +582,7 @@ static void __init kw_i2c_add(struct pmac_i2c_host_kw *host,
>  	bus->close = kw_i2c_close;
>  	bus->xfer = kw_i2c_xfer;
>  	mutex_init(&bus->mutex);
> +	lockdep_register_key(&bus->lock_key);
>  	lockdep_set_class(&bus->mutex, &bus->lock_key);
>  	if (controller == busnode)
>  		bus->flags = pmac_i2c_multibus;
> -- 
> 2.33.1
> 

The patch applied on 5.15.5 but unfortunately was not enough to fix the lockdep bug.

Originally was bug #200055 (https://bugzilla.kernel.org/show_bug.cgi?id=200055).

Regards,
Erhard