linux-kernel - Re: [PATCH v2] scsi: ufs: core: Ensure clk_gating.lock is used only after initialization

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Message-ID: <CAMuHMdUnjKJHtWoNfxTTtm2HD3h3wXbpYPbBsky-PcD+yQTqOw@mail.gmail.com>
Date: Fri, 24 Jan 2025 11:00:45 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Avri Altman <avri.altman@....com>
Cc: "Martin K . Petersen" <martin.petersen@...cle.com>, linux-scsi@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Manivannan Sadhasivam <manisadhasivam.linux@...il.com>, Bart Van Assche <bvanassche@....org>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
	Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v2] scsi: ufs: core: Ensure clk_gating.lock is used only
 after initialization

Hi Avri,

On Fri, Jan 24, 2025 at 8:36 AM Avri Altman <avri.altman@....com> 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, ensure that the spinlock is only used after it
> has been properly initialized before using it in `ufshcd_setup_clocks`.
>
> Fixes: 209f4e43b806 ("scsi: ufs: core: Introduce a new clock_gating lock")
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Avri Altman <avri.altman@....com>
>
> ---
> Changes since v1:
>  - move the spin_lock_init(&hba->clk_gating.lock) call from
>    ufshcd_init_clk_gating() just before the ufshcd_hba_init() call in
>    ufshcd_init() (Bart)

Thanks for the update!

On Renesas R-Car S4 Starter Kit:

    BUG: spinlock bad magic on CPU#6, swapper/0/1
     lock: 0xffffff84443014e8, .magic: 00000000, .owner: <none>/-1,
.owner_cpu: 0
    CPU: 6 UID: 0 PID: 1 Comm: swapper/0 Not tainted
6.13.0-rcar3-initrd-08318-g75abbef32a94 #896
    Hardware name: R-Car S4 Starter Kit board (DT)
    Call trace:
     show_stack+0x18/0x24 (C)
     dump_stack_lvl+0x60/0x80
     dump_stack+0x18/0x24
     spin_bug+0x7c/0xa0
     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+0x288/0xd38
     ufshcd_pltfrm_init+0x618/0x738
     ufs_renesas_probe+0x18/0x24
     platform_probe+0x68/0xb8
     really_probe+0x138/0x268
     __driver_probe_device+0xf4/0x10c
     driver_probe_device+0x3c/0xf8
     __driver_attach+0xf0/0x100
     bus_for_each_dev+0x84/0xdc
     driver_attach+0x24/0x30
     bus_add_driver+0xe8/0x1dc
     driver_register+0xbc/0xf8
     __platform_driver_register+0x24/0x30
     ufs_renesas_platform_init+0x1c/0x28
     do_one_initcall+0x84/0x1f4
     kernel_init_freeable+0x238/0x23c
     kernel_init+0x20/0x120
     ret_from_fork+0x10/0x20

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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