Hi Avri,
On Wed, Jan 22, 2025 at 7:30 AM Avri Altman <avri.altman@xxxxxxx> wrote:
> This commit addresses a lockdep warning triggered by the use of the
> clk_gating.lock before it is properly initialized. The warning is as
> follows:
>
> [ 4.388838] INFO: trying to register non-static key.
> [ 4.395673] The code is fine but needs lockdep annotation, or maybe
> [ 4.402118] you didn't initialize this object before use?
> [ 4.407673] turning off the locking correctness validator.
> [ 4.413334] CPU: 5 UID: 0 PID: 58 Comm: kworker/u32:1 Not tainted 6.12-rc1 #185
> [ 4.413343] Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
> [ 4.413362] Call trace:
> [ 4.413364] show_stack+0x18/0x24 (C)
> [ 4.413374] dump_stack_lvl+0x90/0xd0
> [ 4.413384] dump_stack+0x18/0x24
> [ 4.413392] register_lock_class+0x498/0x4a8
> [ 4.413400] __lock_acquire+0xb4/0x1b90
> [ 4.413406] lock_acquire+0x114/0x310
> [ 4.413413] _raw_spin_lock_irqsave+0x60/0x88
> [ 4.413423] ufshcd_setup_clocks+0x2c0/0x490
> [ 4.413433] ufshcd_init+0x198/0x10ec
> [ 4.413437] ufshcd_pltfrm_init+0x600/0x7c0
> [ 4.413444] ufs_qcom_probe+0x20/0x58
> [ 4.413449] platform_probe+0x68/0xd8
> [ 4.413459] really_probe+0xbc/0x268
> [ 4.413466] __driver_probe_device+0x78/0x12c
> [ 4.413473] driver_probe_device+0x40/0x11c
> [ 4.413481] __device_attach_driver+0xb8/0xf8
> [ 4.413489] bus_for_each_drv+0x84/0xe4
> [ 4.413495] __device_attach+0xfc/0x18c
> [ 4.413502] device_initial_probe+0x14/0x20
> [ 4.413510] bus_probe_device+0xb0/0xb4
> [ 4.413517] deferred_probe_work_func+0x8c/0xc8
> [ 4.413524] process_scheduled_works+0x250/0x658
> [ 4.413534] worker_thread+0x15c/0x2c8
> [ 4.413542] kthread+0x134/0x200
> [ 4.413550] ret_from_fork+0x10/0x20
>
> To fix this issue, we use the existing `is_initialized` flag in the
> `clk_gating` structure to ensure that the spinlock is only used after it
> has been properly initialized. We check this flag before using the
> spinlock in the `ufshcd_setup_clocks` function.
>
> It was incorrect in the first place to call `setup_clocks()` before
> `ufshcd_init_clk_gating()`, and the introduction of the new lock
> unmasked this bug.
>
> Fixes: 209f4e43b806 ("scsi: ufs: core: Introduce a new clock_gating lock")
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
Thanks for your patch!
I just ran into the same issue on R-Car S4 (S4 Starter Kit).
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -9142,7 +9142,7 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
> if (!IS_ERR_OR_NULL(clki->clk) && clki->enabled)
> clk_disable_unprepare(clki->clk);
> }
> - } else if (!ret && on) {
> + } else if (!ret && on && hba->clk_gating.is_initialized) {
> scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
> hba->clk_gating.state = CLKS_ON;
> trace_ufshcd_clk_gating(dev_name(hba->dev),
This looks like a very fragile solution to me...
In addition, while this change does fix this particular spinlock
warning, it just BUGs in a different place later:
do_raw_spin_lock+0x34/0xb4
_raw_spin_lock_irqsave+0x1c/0x30
class_spinlock_irqsave_constructor+0x18/0x30
- ufshcd_setup_clocks+0x98/0x23c
- ufshcd_init+0x268/0xd2c
+ ufshcd_release+0x30/0x74
+ ufshcd_send_uic_cmd+0x70/0x90
+ ufshcd_link_startup.constprop.0+0x70/0x258
+ ufshcd_init+0xa38/0xd2c
ufshcd_pltfrm_init+0x618/0x738
ufs_renesas_probe+0x18/0x24
platform_probe+0x68/0xb8
I think you should initialize all your spinlocks (and mutexes) early
in ufshcd_init(), instead of sprinkled across various helper functions.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
