RE: [PATCH v5 3/4] scsi: ufs: core: Introduce a new clock_gating lock

[Avri Altman]

> > > @@ -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.
Thanks for reporting this.
How about just:
+++ b/drivers/ufs/core/ufshcd.c
@@ -9166,7 +9166,7 @@ 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),

What do you think?

Thanks,
Avri

> >
> > While submitting the fix, please add the following reported by tag:
> >
> > Reported-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> >
> > - Mani
> >
> > --
> > மணிவண்ணன் சதாசிவம்
> 
> --
> மணிவண்ணன் சதாசிவம்