linux-kernel - Re: [PATCH v3 1/2] scsi: ufs: core: Ensure clk_gating.lock is used only after initialization

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Message-ID: <CAMuHMdUrBf1YSLE-0Nz19HFyYpm=Pi0XW1vXkJZS8eE=7rhkyw@mail.gmail.com>
Date: Mon, 27 Jan 2025 10:54:32 +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>, 
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>, 
	Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] scsi: ufs: core: Ensure clk_gating.lock is used
 only after initialization

Hi Avri,

On Sun, 26 Jan 2025 at 07:48, 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`.
> Do that unconditionally as initializing a spinlock is a fast operation.
>
> 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>

Thank you, this fixes the similar BUG (s/ufs_qcom_probe/ufs_renesas_probe/)
I was seeing on the Renesas R-Car S4 Starter Kit.
Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>

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