[PATCH] drm/amdgpu: Add autodump debugfs node for gpu reset
Pierre-Eric Pelloux-Prayer
pierre-eric.pelloux-prayer at amd.com
Fri Apr 24 08:30:52 UTC 2020
Running "umr --autodump" currently does the following:
- open the debugfs autodump file
- wait for a hang (using poll)
- dump gfx rings
- close the file and exit
I don't think adding support for a "Done" message is necessary, but I'd expect to
be able to restart "umr --autodump" and be able to perform another dump.
Pierre-Eric
On 24/04/2020 10:24, Zhao, Jiange wrote:
> [AMD Official Use Only - Internal Distribution Only]
>
>
> Hi,
>
> Of course, considering all the suggestions, I will implement a write callback for usermode app to notify KMD that a dump is finished by sending "Done".
>
> In this way, usermode app can do multiple dumps without closing the node,
>
> Jiange
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> *From:* Pelloux-prayer, Pierre-eric <Pierre-eric.Pelloux-prayer at amd.com>
> *Sent:* Friday, April 24, 2020 3:46 PM
> *To:* Zhao, Jiange <Jiange.Zhao at amd.com>; Koenig, Christian <Christian.Koenig at amd.com>; amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>
> *Cc:* Deucher, Alexander <Alexander.Deucher at amd.com>; Pelloux-prayer, Pierre-eric <Pierre-eric.Pelloux-prayer at amd.com>; Kuehling, Felix <Felix.Kuehling at amd.com>; Liu, Monk <Monk.Liu at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>
> *Subject:* Re: [PATCH] drm/amdgpu: Add autodump debugfs node for gpu reset
>
> Hi Jiange,
>
> FYI I'm working on adding a new "--autodump" command to umr that uses this feature.
> This is not yet merged but you can find the code here: https://gitlab.freedesktop.org/pepp/umr/-/tree/autodump
>
>> (3) At the same time, considering the use case of this node, I believe that only the first GPU reset is worthy of a dump.
>
> If it's possible I'd like to be able to do multiple dumps instead of limiting ourselves to only the first one.
>
> Thanks!
> Pierre-Eric
>
>
>
>> (4) I didn't implement race condition guard because I believe that this node caters for a cautious super-user and a single client is enough to do all the work. I can add the logic if you think it is necessary.
>>
>> Jiange
>>
>> -----Original Message-----
>> From: Koenig, Christian <Christian.Koenig at amd.com>
>> Sent: Thursday, April 23, 2020 4:53 PM
>> To: Zhao, Jiange <Jiange.Zhao at amd.com>; amd-gfx at lists.freedesktop.org
>> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>; Pelloux-prayer, Pierre-eric <Pierre-eric.Pelloux-prayer at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>; Zhang, Hawking <Hawking.Zhang at amd.com>; Liu, Monk <Monk.Liu at amd.com>; Zhao, Jiange <Jiange.Zhao at amd.com>
>> Subject: Re: [PATCH] drm/amdgpu: Add autodump debugfs node for gpu reset
>>
>> Am 23.04.20 um 09:19 schrieb jianzh at amd.com:
>>> From: Jiange Zhao <Jiange.Zhao at amd.com>
>>>
>>> When GPU got timeout, it would notify an interested part of an
>>> opportunity to dump info before actual GPU reset.
>>>
>>> A usermode app would open 'autodump' node under debugfs system and
>>> poll() for readable/writable. When a GPU reset is due, amdgpu would
>>> notify usermode app through wait_queue_head and give it 10 minutes to
>>> dump info.
>>>
>>> After usermode app has done its work, this 'autodump' node is closed.
>>> On node closure, amdgpu gets to know the dump is done through the
>>> completion that is triggered in release().
>>>
>>> There is no write or read callback because necessary info can be
>>> obtained through dmesg and umr. Messages back and forth between
>>> usermode app and amdgpu are unnecessary.
>>>
>>> Signed-off-by: Jiange Zhao <Jiange.Zhao at amd.com>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 9 +++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 85 +++++++++++++++++++++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h | 1 +
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +
>>> 4 files changed, 97 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index bc1e0fd71a09..a505b547f242 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -724,6 +724,13 @@ struct amd_powerplay {
>>> const struct amd_pm_funcs *pp_funcs;
>>> };
>>>
>>> +struct amdgpu_autodump {
>>> + bool registered;
>>> + struct completion completed;
>>
>> Registered and completed seems to have the same meaning.
>>
>>> + struct dentry *dentry;
>>> + struct wait_queue_head gpu_hang_wait;
>>> +};
>>> +
>>> #define AMDGPU_RESET_MAGIC_NUM 64
>>> #define AMDGPU_MAX_DF_PERFMONS 4
>>> struct amdgpu_device {
>>> @@ -990,6 +997,8 @@ struct amdgpu_device {
>>> char product_number[16];
>>> char product_name[32];
>>> char serial[16];
>>> +
>>> + struct amdgpu_autodump autodump;
>>> };
>>>
>>> static inline struct amdgpu_device *amdgpu_ttm_adev(struct
>>> ttm_bo_device *bdev) diff --git
>>> a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> index 1a4894fa3693..cdd4bf00adee 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> @@ -74,8 +74,91 @@ int amdgpu_debugfs_add_files(struct amdgpu_device *adev,
>>> return 0;
>>> }
>>>
>>> +int amdgpu_debugfs_wait_dump(struct amdgpu_device *adev) { #if
>>> +defined(CONFIG_DEBUG_FS)
>>> + int ret;
>>> + unsigned long tmo = 600*HZ;
>>
>> In general please declare constant lines first and variable like "i" or "r" last.
>>
>>> +
>>> + if (!adev->autodump.registered)
>>> + return 0;
>>> +
>>> + wake_up_interruptible(&adev->autodump.gpu_hang_wait);
>>> +
>>> + ret =
>>> +wait_for_completion_interruptible_timeout(&adev->autodump.completed,
>>> +tmo);
>>
>> This is racy, in other words it can happen that a new client opens up the debugfs file without being signaled but blocks the reset here.
>>
>> You could use two completion structures to avoid that.
>>
>>> + if (ret == 0) { /* time out and dump tool still not finish its dump*/
>>> + pr_err("autodump: timeout before dump finished, move on to gpu recovery\n");
>>> + return -ETIMEDOUT;
>>> + }
>>> +#endif
>>> + return 0;
>>> +}
>>> +
>>> #if defined(CONFIG_DEBUG_FS)
>>>
>>> +static int amdgpu_debugfs_autodump_open(struct inode *inode, struct
>>> +file *file) {
>>> + int ret;
>>> + struct amdgpu_device *adev;
>>> +
>>> + ret = simple_open(inode, file);
>>> + if (ret)
>>> + return ret;
>>> +
>>> + adev = file->private_data;
>>> + if (adev->autodump.registered == true)
>>> + return -EINVAL;
>>
>> Probably better to return -EBUSY here. And this is racy, and might need a lock e.g. multiple clients could open the file at the same time.
>>
>> If we use a struct completion for registered we could use the spinlock of that one for protection here.
>>
>>> +
>>> + adev->autodump.registered = true;
>>
>> You also need to reset the completion structure here otherwise only the first GPU reset would work with this.
>>
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int amdgpu_debugfs_autodump_release(struct inode *inode,
>>> +struct file *file) {
>>> + struct amdgpu_device *adev = file->private_data;
>>> +
>>> + complete(&adev->autodump.completed);
>>> + adev->autodump.registered = false;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +unsigned int amdgpu_debugfs_autodump_poll(struct file *file, struct
>>> +poll_table_struct *poll_table) {
>>> + struct amdgpu_device *adev = file->private_data;
>>> +
>>> + poll_wait(file, &adev->autodump.gpu_hang_wait, poll_table);
>>> +
>>> + if (adev->in_gpu_reset)
>>> + return POLLIN | POLLRDNORM | POLLWRNORM;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static const struct file_operations autodump_debug_fops = {
>>> + .owner = THIS_MODULE,
>>> + .open = amdgpu_debugfs_autodump_open,
>>> + .poll = amdgpu_debugfs_autodump_poll,
>>> + .release = amdgpu_debugfs_autodump_release, };
>>> +
>>> +static int amdgpu_debugfs_autodump_init(struct amdgpu_device *adev) {
>>> + struct dentry *entry;
>>> +
>>> + init_completion(&adev->autodump.completed);
>>> + init_waitqueue_head(&adev->autodump.gpu_hang_wait);
>>> + adev->autodump.registered = false;
>>> +
>>> + entry = debugfs_create_file("autodump", 0600,
>>> + adev->ddev->primary->debugfs_root,
>>> + adev, &autodump_debug_fops);
>>> + adev->autodump.dentry = entry;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> /**
>>> * amdgpu_debugfs_process_reg_op - Handle MMIO register reads/writes
>>> *
>>> @@ -1434,6 +1517,8 @@ int amdgpu_debugfs_init(struct amdgpu_device
>>> *adev)
>>>
>>> amdgpu_ras_debugfs_create_all(adev);
>>>
>>> + amdgpu_debugfs_autodump_init(adev);
>>> +
>>> return amdgpu_debugfs_add_files(adev, amdgpu_debugfs_list,
>>> ARRAY_SIZE(amdgpu_debugfs_list));
>>> }
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
>>> index de12d1101526..9428940a696d 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.h
>>> @@ -40,3 +40,4 @@ int amdgpu_debugfs_add_files(struct amdgpu_device *adev,
>>> int amdgpu_debugfs_fence_init(struct amdgpu_device *adev);
>>> int amdgpu_debugfs_firmware_init(struct amdgpu_device *adev);
>>> int amdgpu_debugfs_gem_init(struct amdgpu_device *adev);
>>> +int amdgpu_debugfs_wait_dump(struct amdgpu_device *adev);
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index 3d601d5dd5af..44e54ea7af0f 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -3915,6 +3915,8 @@ static int amdgpu_device_pre_asic_reset(struct amdgpu_device *adev,
>>> int i, r = 0;
>>> bool need_full_reset = *need_full_reset_arg;
>>>
>>> + amdgpu_debugfs_wait_dump(adev);
>>> +
>>> /* block all schedulers and reset given job's ring */
>>> for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
>>> struct amdgpu_ring *ring = adev->rings[i];
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