[PATCH] drm/amdgpu: Add autodump debugfs node for gpu reset
Pierre-Eric Pelloux-Prayer
pierre-eric.pelloux-prayer at amd.com
Fri Apr 24 07:46:53 UTC 2020
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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