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

[Zytaruk, Kelly]

Thanks Guchun.

Tag is okay.

Kelly

-----Original Message-----
From: Chen, Guchun <guchun.c...@amd.com> 
Sent: January 10, 2022 10:01 PM
To: Zytaruk, Kelly <kelly.zyta...@amd.com>; amd-gfx@lists.freedesktop.org; 
Deucher, Alexander <alexander.deuc...@amd.com>; Koenig, Christian 
<christian.koe...@amd.com>; Pan, Xinhui <xinhui....@amd.com>; Huang, Qiliang 
(Warden) <qiliang.hu...@amd.com>; Zhang, Bokun <bokun.zh...@amd.com>
Subject: RE: [PATCH] drm/amdgpu: use spin_lock_irqsave to avoid deadlock by 
local interrupt

[Public]

Thanks Kelly. I will push this patch with a tag like "Tested-by: Zytaruk, Kelly 
<kelly.zyta...@amd.com>". Pls let me know if you have any concern.

Regards,
Guchun

-----Original Message-----
From: Zytaruk, Kelly <kelly.zyta...@amd.com> 
Sent: Monday, January 10, 2022 11:42 PM
To: Chen, Guchun <guchun.c...@amd.com>; amd-gfx@lists.freedesktop.org; Deucher, 
Alexander <alexander.deuc...@amd.com>; Koenig, Christian 
<christian.koe...@amd.com>; Pan, Xinhui <xinhui....@amd.com>; Huang, Qiliang 
(Warden) <qiliang.hu...@amd.com>; Zhang, Bokun <bokun.zh...@amd.com>
Subject: RE: [PATCH] drm/amdgpu: use spin_lock_irqsave to avoid deadlock by 
local interrupt

I can confirm that the fault no longer occurs when the patch is implemented.

Thanks,
Kelly

-----Original Message-----
From: Chen, Guchun <guchun.c...@amd.com> 
Sent: January 10, 2022 12:14 AM
To: amd-gfx@lists.freedesktop.org; Deucher, Alexander 
<alexander.deuc...@amd.com>; Koenig, Christian <christian.koe...@amd.com>; Pan, 
Xinhui <xinhui....@amd.com>; Zytaruk, Kelly <kelly.zyta...@amd.com>; Huang, 
Qiliang (Warden) <qiliang.hu...@amd.com>; Zhang, Bokun <bokun.zh...@amd.com>
Cc: Chen, Guchun <guchun.c...@amd.com>
Subject: [PATCH] drm/amdgpu: use spin_lock_irqsave to avoid deadlock by local 
interrupt

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.c...@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) {
-               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;
        }
--
2.17.1