> On 1/21/25 10:27 PM, Avri Altman 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>
> > ---
> > drivers/ufs/core/ufshcd.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index f6c38cf10382..a778fc51ca2a 100644
> > --- 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),
>
> Has it been considered to move the spin_lock_init(&hba->clk_gating.lock)
> call from ufshcd_init_clk_gating() such that it occurs before its first use, e.g.
> just before the ufshcd_hba_init() call in ufshcd_init()?
While your suggestion has merit, it would unfortunately break the fundamental concept of concentrating the initialization logic in one place, which is essential for maintaining a clean and manageable codebase.
Will do that if you think it's better.
Thanks,
Avri
>
> Thanks,
>
> Bart.
