Am 17.01.22 um 11:09 schrieb Somalapuram, Amaranath:

[AMD Official Use Only]



-----Original Message-----
From: Koenig, Christian <Christian.Koenig@amd.com>
Sent: Monday, January 17, 2022 3:33 PM
To: Somalapuram, Amaranath <Amaranath.Somalapuram@amd.com>; amd-gfx@lists.freedesktop.org
Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Sharma, Shashank <Shashank.Sharma@amd.com>
Subject: Re: [PATCH 2/2] drm/amdgpu: add AMDGPURESET uevent on AMD GPU reset

Am 17.01.22 um 11:01 schrieb Somalapuram, Amaranath:

[AMD Official Use Only]



-----Original Message-----
From: Koenig, Christian <Christian.Koenig@amd.com>
Sent: Monday, January 17, 2022 12:57 PM
To: Somalapuram, Amaranath <Amaranath.Somalapuram@amd.com>;
amd-gfx@lists.freedesktop.org
Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Sharma, Shashank
<Shashank.Sharma@amd.com>
Subject: Re: [PATCH 2/2] drm/amdgpu: add AMDGPURESET uevent on AMD GPU
reset

Am 17.01.22 um 07:33 schrieb Somalapuram Amaranath:

AMDGPURESET uevent added to notify userspace, collect dump_stack and
trace

Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram@amd.com>
---
    drivers/gpu/drm/amd/amdgpu/nv.c | 45 +++++++++++++++++++++++++++++++++
    1 file changed, 45 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/nv.c
b/drivers/gpu/drm/amd/amdgpu/nv.c index 2ec1ffb36b1f..b73147ae41fb
100644
--- a/drivers/gpu/drm/amd/amdgpu/nv.c
+++ b/drivers/gpu/drm/amd/amdgpu/nv.c
@@ -529,10 +529,55 @@ nv_asic_reset_method(struct amdgpu_device *adev)
        }
    }
    +/**
+ * drm_sysfs_reset_event - generate a DRM uevent
+ * @dev: DRM device
+ *
+ * Send a uevent for the DRM device specified by @dev.  Currently we
+only
+ * set AMDGPURESET=1 in the uevent environment, but this could be
+expanded to
+ * deal with other types of events.
+ *
+ * Any new uapi should be using the
+drm_sysfs_connector_status_event()
+ * for uevents on connector status change.
+ */
+void drm_sysfs_reset_event(struct drm_device *dev)

This should probably go directly into the DRM subsystem.

+{
+    char *event_string = "AMDGPURESET=1";
+    char *envp[2] = { event_string, NULL };
+
+    kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);

As I said this approach is a clear NAK. We can't allocate any memory when we do a reset.

Regards,
Christian.

Can I do something like this:

void drm_sysfs_reset_event(struct drm_device *dev)
   {
-       char *event_string = "AMDGPURESET=1";
-       char *envp[2] = { event_string, NULL };
+       char **envp;
+
+       envp = kcalloc(2,sizeof(char *), GFP_ATOMIC);
+       envp[0] = kcalloc(30, sizeof(char), GFP_ATOMIC);
+       envp[1] = kcalloc(30, sizeof(char), GFP_ATOMIC);

No, not really. kobject_uevent_env() will still allocate memory without GFP_ATOMIC.

I think the whole approach of using udev won't work for this.

Regards,
Christian.

I have tested it with sample applications:
Gpu reset:
sudo cat /sys/kernel/debug/dri/0/amdgpu_gpu_recover

And I never missed the AMDGPURESET=1 event in user space,

That's not the problem. Allocating memory when we need to do a reset can cause a *HARD* kernel deadlock.

This is absolutely not something we can do and Daniel even tried to add a few lockdep annotations for this.

So automated testing scripts will complain that this won't work.

Regards,
Christian.

Regards,

S.Amarnath

even with continues resets with sudo cat /sys/kernel/debug/dri/0/amdgpu_gpu_recover .

Regards,
S.Amarnath

+
+       strcpy(envp[0], "AMDGPURESET=1");
+       strcpy(envp[1], "");
+

          kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE,
envp);
+
+       kfree(envp[0]);
+       kfree(envp[1]);
+       kfree(envp);
   }

Regards,
S.Amarnath

+}
+
+void amdgpu_reset_dumps(struct amdgpu_device *adev) {
+    struct drm_device *ddev = adev_to_drm(adev);
+    int r = 0, i;
+
+    /* original raven doesn't have full asic reset */
+    if ((adev->apu_flags & AMD_APU_IS_RAVEN) &&
+        !(adev->apu_flags & AMD_APU_IS_RAVEN2))
+        return;
+    for (i = 0; i < adev->num_ip_blocks; i++) {
+        if (!adev->ip_blocks[i].status.valid)
+            continue;
+        if (!adev->ip_blocks[i].version->funcs->reset_reg_dumps)
+            continue;
+        r = adev->ip_blocks[i].version->funcs->reset_reg_dumps(adev);
+
+        if (r)
+            DRM_ERROR("reset_reg_dumps of IP block <%s> failed %d\n",
+                    adev->ip_blocks[i].version->funcs->name, r);
+    }
+
+    drm_sysfs_reset_event(ddev);
+    dump_stack();
+}
+
    static int nv_asic_reset(struct amdgpu_device *adev)
    {
        int ret = 0;
    +    amdgpu_reset_dumps(adev);
        switch (nv_asic_reset_method(adev)) {
        case AMD_RESET_METHOD_PCI:
            dev_info(adev->dev, "PCI reset\n");