[PATCH] drm/amdgpu: use spin_lock_irqsave to avoid deadlock by local interrupt

[Christian König]

Am 11.01.22 um 06:21 schrieb Guchun Chen:
> This is observed in SRIOV case with virtual KMS as display.
>
> _raw_spin_lock_irqsave+0x37/0x40
> drm_handle_vblank+0x69/0x350 [drm]
> ? try_to_wake_up+0x432/0x5c0
> ? amdgpu_vkms_prepare_fb+0x1c0/0x1c0 [amdgpu]
> drm_crtc_handle_vblank+0x17/0x20 [drm]
> amdgpu_vkms_vblank_simulate+0x4d/0x80 [amdgpu]
> __hrtimer_run_queues+0xfb/0x230
> hrtimer_interrupt+0x109/0x220
> __sysvec_apic_timer_interrupt+0x64/0xe0
> asm_call_irq_on_stack+0x12/0x20
>
> Fixes: ba5317109d0c("drm/amdgpu: create amdgpu_vkms (v4)")
> Signed-off-by: Guchun Chen <guchun.chen at amd.com>
> Acked-by: Alex Deucher <alexander.deucher at amd.com>
> Tested-by: Kelly Zytaruk <kelly.zytaruk at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> index 2dcc68e04e84..d99c8779b51e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vkms.c
> @@ -144,15 +144,16 @@ static void amdgpu_vkms_crtc_atomic_disable(struct drm_crtc *crtc,
>   static void amdgpu_vkms_crtc_atomic_flush(struct drm_crtc *crtc,
>   					  struct drm_atomic_state *state)
>   {
> +	unsigned long flags;
>   	if (crtc->state->event) {

Please add an empty line between decleration and code, apart from that 
feel free to add an Acked-by: Christian König <christian.koenig at amd.com> 
to the patch as well.

Regards,
Christian.

> -		spin_lock(&crtc->dev->event_lock);
> +		spin_lock_irqsave(&crtc->dev->event_lock, flags);
>   
>   		if (drm_crtc_vblank_get(crtc) != 0)
>   			drm_crtc_send_vblank_event(crtc, crtc->state->event);
>   		else
>   			drm_crtc_arm_vblank_event(crtc, crtc->state->event);
>   
> -		spin_unlock(&crtc->dev->event_lock);
> +		spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
>   
>   		crtc->state->event = NULL;
>   	}