> Hi Avri,
>
> Thanks for your patch!
>
> On Sun, 26 Jan 2025 at 07:48, Avri Altman <avri.altman@xxxxxxx> wrote:
> > This commit addresses an issue where `clk_gating.state` is being
> > toggled in `ufshcd_setup_clocks` even if clock gating is not allowed.
> > This can lead to a crash with the following error:
> >
> > 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
>
> Note that after "[PATCH v3 1/2] scsi: ufs: core: Ensure clk_gating.lock is used
> only after initialization", I no longer see the above BUG(), so I don't think it's
> a good idea to include this log.
Done. Will remove.
>
> > The root cause of the issue is that `clk_gating.state` is being
> > toggled even if clock gating is not allowed. This can lead to the
> > spinlock being used before it is properly initialized.
>
> Which doesn't mean the underlying issue no longer exists...
Done. Will rephrase.
Thanks,
Avri
>
> > The fix is to add a check for `hba->clk_gating.is_initialized` before
> > toggling `clk_gating.state` in `ufshcd_setup_clocks`. Since
> > `clk_gating.lock` is now initialized unconditionally, this is for
> > documentation purposes, to ensure clarity in the code. The primary fix
> > remains to prevent toggling the `clk_gating.state` if clock gating is
> > not allowed.
> >
> > Fixes: 1ab27c9cf8b6 ("ufs: Add support for clock gating")
> > Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
>
> Seems to work fine on R-Car S4 SK, so
> Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> 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
