linux-kernel - Re: [PATCH] drm/hisilicon: Fix rmmod hibmc

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Message-ID: <3f32c165-9a83-6238-46dd-9ace8280b584@suse.de>
Date:   Tue, 15 Dec 2020 08:53:16 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Tian Tao <tiantao6@...ilicon.com>, airlied@...ux.ie,
        daniel@...ll.ch, kraxel@...hat.com, alexander.deucher@....com,
        tglx@...utronix.de, dri-devel@...ts.freedesktop.org,
        xinliang.liu@...aro.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/hisilicon: Fix rmmod hibmc_drm failed

Hi Tian

Am 15.12.20 um 04:01 schrieb Tian Tao:
> drm_irq_uninstall should be called before pci_disable_msi, if use
> devm_drm_irq_install to register the interrupt, the system will
> call pci_disable_msi first and then call drm_irq_uninstall, which
>   will result in the following callstack.
> 
> kernel BUG at drivers/pci/msi.c:376!
> Internal error: Oops - BUG: 0 [#1] SMP
> CPU: 93 PID: 173814 Comm: rmmod Tainted:
> pstate: a0400009 (NzCv daif +PAN -UAO -TCO BTYPE=--)
> pc : free_msi_irqs+0x17c/0x1a0
> lr : free_msi_irqs+0x16c/0x1a0
> sp : ffff2028157f7bd0
> x29: ffff2028157f7bd0 x28: ffff202849edab00
> x27: 0000000000000000 x26: 0000000000000000
> x25: 0000000000000000 x24: 0000000000000000
> x23: ffff0020851da000 x22: ffff0020851da2d8
> x21: ffff0020cc829000 x20: 0000000000000000
> x19: ffff0020d6714800 x18: 0000000000000010
> x17: 0000000000000000 x16: 0000000000000000
> x15: ffffffffffffffff x14: ffff2028957f77df
> x13: ffff2028157f77ed x12: 0000000000000000
> x11: 0000000000000040 x10: ffff800011b2f8e0
> x9 : ffff800011b2f8d8 x8 : ffff2020203fc458
> x7 : 0000000000000000 x6 : 0000000000000000
> x5 : ffff2020203fc430 x4 : ffff2020203fc4a0
> x3 : 0000000000000000 x2 : 0000000000000000
> x1 : 00000000000002c9 x0 : ffff0020d6719500
> Call trace:
>   free_msi_irqs+0x17c/0x1a0
>   pci_disable_msi+0xe4/0x118
>   hibmc_unload+0x44/0x80 [hibmc_drm]
>   hibmc_pci_remove+0x2c/0x38 [hibmc_drm]
>   pci_device_remove+0x48/0x108
>   device_release_driver_internal+0x118/0x1f0
>   driver_detach+0x6c/0xe0
>   bus_remove_driver+0x74/0x100
>   driver_unregister+0x34/0x60
>   pci_unregister_driver+0x24/0xd8
>   hibmc_pci_driver_exit+0x14/0xe768 [hibmc_drm]
>   __arm64_sys_delete_module+0x1fc/0x2d0
>   el0_svc_common.constprop.3+0xa8/0x188
>   do_el0_svc+0x80/0xa0
>   el0_sync_handler+0x8c/0xb0
>   el0_sync+0x15c/0x180
> Code: f940b400 b4ffff00 a903e7b8 f90013b5 (d4210000)
> ---[ end trace 310d94ee8abef44f ]---
> Kernel panic - not syncing: Oops - BUG: Fatal exception
> 
> Signed-off-by: Tian Tao <tiantao6@...ilicon.com>
> ---
>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> index e3ab765b..02f3bd1 100644
> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> @@ -251,6 +251,10 @@ static int hibmc_hw_init(struct hibmc_drm_private *priv)
>   static int hibmc_unload(struct drm_device *dev)
>   {
>   	drm_atomic_helper_shutdown(dev);
> +
> +	if (dev->irq_enabled)
> +		drm_irq_uninstall(dev);
> +
>   	pci_disable_msi(dev->pdev);

We're trying to move towards managed driver releases; and this feels 
like a step backwards.

I looked through the PCI-device release code in pcim_release() and it 
already disables MSI automatically. [1] You can enable the PCI device 
with pcim_enable_device() instead of pci_enable_device() to use the 
automatic release. No more need to disable MSI manually.

If this does not work, could you provide a managed version of 
pci_disable_msi() that solves the problem?

Best regards
Thomas

[1] https://elixir.bootlin.com/linux/latest/source/drivers/pci/pci.c#L1976


>   
>   	return 0;
> @@ -286,7 +290,7 @@ static int hibmc_load(struct drm_device *dev)
>   	if (ret) {
>   		drm_warn(dev, "enabling MSI failed: %d\n", ret);
>   	} else {
> -		ret = devm_drm_irq_install(dev, dev->pdev->irq);
> +		ret = drm_irq_install(dev, dev->pdev->irq);
>   		if (ret)
>   			drm_warn(dev, "install irq failed: %d\n", ret);
>   	}
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer



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