linux-kernel - Re: [PATCH v5 3/4] scsi: ufs: core: Introduce a new clock

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Message-ID: <20250121124638.ess5iqn6weyw6jzg@thinkpad>
Date: Tue, 21 Jan 2025 18:16:38 +0530
From: Manivannan Sadhasivam <manisadhasivam.linux@...il.com>
To: Avri Altman <avri.altman@....com>
Cc: "Martin K . Petersen" <martin.petersen@...cle.com>,
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bart Van Assche <bvanassche@....org>, Bean Huo <beanhuo@...ron.com>,
	dmitry.baryshkov@...aro.org
Subject: Re: [PATCH v5 3/4] scsi: ufs: core: Introduce a new clock_gating lock

On Tue, Jan 21, 2025 at 06:12:23PM +0530, Manivannan Sadhasivam wrote:
> + Dmitry
> 

Oops. Missed CCing Dmitry. Added now.

- Mani

> On Sun, Nov 24, 2024 at 09:08:07AM +0200, Avri Altman wrote:
> 
> [...]
> 
> > @@ -9162,7 +9159,6 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
> >  	int ret = 0;
> >  	struct ufs_clk_info *clki;
> >  	struct list_head *head = &hba->clk_list_head;
> > -	unsigned long flags;
> >  	ktime_t start = ktime_get();
> >  	bool clk_state_changed = false;
> >  
> > @@ -9213,11 +9209,10 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
> >  				clk_disable_unprepare(clki->clk);
> >  		}
> >  	} else if (!ret && on) {
> > -		spin_lock_irqsave(hba->host->host_lock, flags);
> > -		hba->clk_gating.state = CLKS_ON;
> > +		scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
> 
> This triggers the following lockdep warning on Qualcomm boards as reported by
> Dmitry offline:
> 
> [    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
> 
> As lockdep found, clk_gating.lock is uninitialized when ufshcd_setup_clocks() is
> called for the first time. I looked into fixing it for a moment, but the overall
> locking for 'clk_gating.state' looks fragile i.e., there are instances where the
> code is not locked at all. So I'm just reporting to you here hoping that you'd
> have some idea to fix it.
> 
> While submitting the fix, please add the following reported by tag:
> 
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> 
> - Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்

-- 
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