On 6/22/20 7:21 AM, Greg KH wrote:
> On Mon, Jun 22, 2020 at 11:51:24AM +0200, Daniel Vetter wrote:
>> On Sun, Jun 21, 2020 at 02:03:05AM -0400, Andrey Grodzovsky wrote:
>>> Track sysfs files in a list so they all can be removed during pci remove
>>> since otherwise their removal after that causes crash because parent
>>> folder was already removed during pci remove.
> Huh?  That should not happen, do you have a backtrace of that crash?


2 examples in the attached trace.

Andrey


>
>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>> Uh I thought sysfs just gets yanked completely. Please check with Greg KH
>> whether hand-rolling all this really is the right solution here ... Feels
>> very wrong. I thought this was all supposed to work by adding attributes
>> before publishing the sysfs node, and then letting sysfs clean up
>> everything. Not by cleaning up manually yourself.
> Yes, that is supposed to be the correct thing to do.
>
>> Adding Greg for an authoritative answer.
>> -Daniel
>>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h          | 13 +++++++++++
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c |  7 +++++-
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c   | 35 ++++++++++++++++++++++++----
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c  | 12 ++++++----
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c      |  8 ++++++-
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 17 ++++++++++++--
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c     | 13 ++++++++++-
>>>   drivers/gpu/drm/amd/amdgpu/df_v3_6.c         | 10 +++++---
>>>   8 files changed, 99 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 604a681..ba3775f 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -726,6 +726,15 @@ struct amd_powerplay {
>>>   
>>>   #define AMDGPU_RESET_MAGIC_NUM 64
>>>   #define AMDGPU_MAX_DF_PERFMONS 4
>>> +
>>> +struct amdgpu_sysfs_list_node {
>>> +	struct list_head head;
>>> +	struct device_attribute *attr;
>>> +};
> You know we have lists of attributes already, called attribute groups,
> if you really wanted to do something like this.  But, I don't think so.
>
> Either way, don't hand-roll your own stuff that the driver core has
> provided for you for a decade or more, that's just foolish :)
>
>>> +
>>> +#define AMDGPU_DEVICE_ATTR_LIST_NODE(_attr) \
>>> +	struct amdgpu_sysfs_list_node dev_attr_handle_##_attr = {.attr = &dev_attr_##_attr}
>>> +
>>>   struct amdgpu_device {
>>>   	struct device			*dev;
>>>   	struct drm_device		*ddev;
>>> @@ -992,6 +1001,10 @@ struct amdgpu_device {
>>>   	char				product_number[16];
>>>   	char				product_name[32];
>>>   	char				serial[16];
>>> +
>>> +	struct list_head sysfs_files_list;
>>> +	struct mutex	 sysfs_files_list_lock;
>>> +
>>>   };
>>>   
>>>   static inline struct amdgpu_device *amdgpu_ttm_adev(struct ttm_bo_device *bdev)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>>> index fdd52d8..c1549ee 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>>> @@ -1950,8 +1950,10 @@ static ssize_t amdgpu_atombios_get_vbios_version(struct device *dev,
>>>   	return snprintf(buf, PAGE_SIZE, "%s\n", ctx->vbios_version);
>>>   }
>>>   
>>> +
>>>   static DEVICE_ATTR(vbios_version, 0444, amdgpu_atombios_get_vbios_version,
>>>   		   NULL);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(vbios_version);
>>>   
>>>   /**
>>>    * amdgpu_atombios_fini - free the driver info and callbacks for atombios
>>> @@ -1972,7 +1974,6 @@ void amdgpu_atombios_fini(struct amdgpu_device *adev)
>>>   	adev->mode_info.atom_context = NULL;
>>>   	kfree(adev->mode_info.atom_card_info);
>>>   	adev->mode_info.atom_card_info = NULL;
>>> -	device_remove_file(adev->dev, &dev_attr_vbios_version);
>>>   }
>>>   
>>>   /**
>>> @@ -2038,6 +2039,10 @@ int amdgpu_atombios_init(struct amdgpu_device *adev)
>>>   		return ret;
>>>   	}
>>>   
>>> +	mutex_lock(&adev->sysfs_files_list_lock);
>>> +	list_add_tail(&dev_attr_handle_vbios_version.head, &adev->sysfs_files_list);
>>> +	mutex_unlock(&adev->sysfs_files_list_lock);
>>> +
>>>   	return 0;
>>>   }
>>>   
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index e7b9065..3173046 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -2928,6 +2928,12 @@ static const struct attribute *amdgpu_dev_attributes[] = {
>>>   	NULL
>>>   };
>>>   
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(product_name);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(product_number);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(serial_number);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(pcie_replay_count);
>>> +
>>> +
>>>   /**
>>>    * amdgpu_device_init - initialize the driver
>>>    *
>>> @@ -3029,6 +3035,9 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>>>   	INIT_LIST_HEAD(&adev->shadow_list);
>>>   	mutex_init(&adev->shadow_list_lock);
>>>   
>>> +	INIT_LIST_HEAD(&adev->sysfs_files_list);
>>> +	mutex_init(&adev->sysfs_files_list_lock);
>>> +
>>>   	INIT_DELAYED_WORK(&adev->delayed_init_work,
>>>   			  amdgpu_device_delayed_init_work_handler);
>>>   	INIT_DELAYED_WORK(&adev->gfx.gfx_off_delay_work,
>>> @@ -3281,6 +3290,13 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>>>   	if (r) {
>>>   		dev_err(adev->dev, "Could not create amdgpu device attr\n");
>>>   		return r;
>>> +	} else {
>>> +		mutex_lock(&adev->sysfs_files_list_lock);
>>> +		list_add_tail(&dev_attr_handle_product_name.head, &adev->sysfs_files_list);
>>> +		list_add_tail(&dev_attr_handle_product_number.head, &adev->sysfs_files_list);
>>> +		list_add_tail(&dev_attr_handle_serial_number.head, &adev->sysfs_files_list);
>>> +		list_add_tail(&dev_attr_handle_pcie_replay_count.head, &adev->sysfs_files_list);
>>> +		mutex_unlock(&adev->sysfs_files_list_lock);
>>>   	}
>>>   
>>>   	if (IS_ENABLED(CONFIG_PERF_EVENTS))
>>> @@ -3298,6 +3314,16 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>>>   	return r;
>>>   }
>>>   
>>> +static void amdgpu_sysfs_remove_files(struct amdgpu_device *adev)
>>> +{
>>> +	struct amdgpu_sysfs_list_node *node;
>>> +
>>> +	mutex_lock(&adev->sysfs_files_list_lock);
>>> +	list_for_each_entry(node, &adev->sysfs_files_list, head)
>>> +		device_remove_file(adev->dev, node->attr);
>>> +	mutex_unlock(&adev->sysfs_files_list_lock);
>>> +}
>>> +
>>>   /**
>>>    * amdgpu_device_fini - tear down the driver
>>>    *
>>> @@ -3332,6 +3358,11 @@ void amdgpu_device_fini_early(struct amdgpu_device *adev)
>>>   	amdgpu_fbdev_fini(adev);
>>>   
>>>   	amdgpu_irq_fini_early(adev);
>>> +
>>> +	amdgpu_sysfs_remove_files(adev);
>>> +
>>> +	if (adev->ucode_sysfs_en)
>>> +		amdgpu_ucode_sysfs_fini(adev);
>>>   }
>>>   
>>>   void amdgpu_device_fini_late(struct amdgpu_device *adev)
>>> @@ -3366,10 +3397,6 @@ void amdgpu_device_fini_late(struct amdgpu_device *adev)
>>>   	adev->rmmio = NULL;
>>>   	amdgpu_device_doorbell_fini(adev);
>>>   
>>> -	if (adev->ucode_sysfs_en)
>>> -		amdgpu_ucode_sysfs_fini(adev);
>>> -
>>> -	sysfs_remove_files(&adev->dev->kobj, amdgpu_dev_attributes);
>>>   	if (IS_ENABLED(CONFIG_PERF_EVENTS))
>>>   		amdgpu_pmu_fini(adev);
>>>   	if (amdgpu_discovery && adev->asic_type >= CHIP_NAVI10)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
>>> index 6271044..e7b6c4a 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
>>> @@ -76,6 +76,9 @@ static DEVICE_ATTR(mem_info_gtt_total, S_IRUGO,
>>>   static DEVICE_ATTR(mem_info_gtt_used, S_IRUGO,
>>>   	           amdgpu_mem_info_gtt_used_show, NULL);
>>>   
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_gtt_total);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_gtt_used);
>>> +
>>>   /**
>>>    * amdgpu_gtt_mgr_init - init GTT manager and DRM MM
>>>    *
>>> @@ -114,6 +117,11 @@ static int amdgpu_gtt_mgr_init(struct ttm_mem_type_manager *man,
>>>   		return ret;
>>>   	}
>>>   
>>> +	mutex_lock(&adev->sysfs_files_list_lock);
>>> +	list_add_tail(&dev_attr_handle_mem_info_gtt_total.head, &adev->sysfs_files_list);
>>> +	list_add_tail(&dev_attr_handle_mem_info_gtt_used.head, &adev->sysfs_files_list);
>>> +	mutex_unlock(&adev->sysfs_files_list_lock);
>>> +
>>>   	return 0;
>>>   }
>>>   
>>> @@ -127,7 +135,6 @@ static int amdgpu_gtt_mgr_init(struct ttm_mem_type_manager *man,
>>>    */
>>>   static int amdgpu_gtt_mgr_fini(struct ttm_mem_type_manager *man)
>>>   {
>>> -	struct amdgpu_device *adev = amdgpu_ttm_adev(man->bdev);
>>>   	struct amdgpu_gtt_mgr *mgr = man->priv;
>>>   	spin_lock(&mgr->lock);
>>>   	drm_mm_takedown(&mgr->mm);
>>> @@ -135,9 +142,6 @@ static int amdgpu_gtt_mgr_fini(struct ttm_mem_type_manager *man)
>>>   	kfree(mgr);
>>>   	man->priv = NULL;
>>>   
>>> -	device_remove_file(adev->dev, &dev_attr_mem_info_gtt_total);
>>> -	device_remove_file(adev->dev, &dev_attr_mem_info_gtt_used);
>>> -
>>>   	return 0;
>>>   }
>>>   
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
>>> index ddb4af0c..554fec0 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
>>> @@ -2216,6 +2216,8 @@ static DEVICE_ATTR(usbc_pd_fw, S_IRUGO | S_IWUSR,
>>>   		   psp_usbc_pd_fw_sysfs_read,
>>>   		   psp_usbc_pd_fw_sysfs_write);
>>>   
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(usbc_pd_fw);
>>> +
>>>   
>>>   
>>>   const struct amd_ip_funcs psp_ip_funcs = {
>>> @@ -2242,13 +2244,17 @@ static int psp_sysfs_init(struct amdgpu_device *adev)
>>>   
>>>   	if (ret)
>>>   		DRM_ERROR("Failed to create USBC PD FW control file!");
>>> +	else {
>>> +		mutex_lock(&adev->sysfs_files_list_lock);
>>> +		list_add_tail(&dev_attr_handle_usbc_pd_fw.head, &adev->sysfs_files_list);
>>> +		mutex_unlock(&adev->sysfs_files_list_lock);
>>> +	}
>>>   
>>>   	return ret;
>>>   }
>>>   
>>>   static void psp_sysfs_fini(struct amdgpu_device *adev)
>>>   {
>>> -	device_remove_file(adev->dev, &dev_attr_usbc_pd_fw);
>>>   }
>>>   
>>>   const struct amdgpu_ip_block_version psp_v3_1_ip_block =
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> index 7723937..39c400c 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>>> @@ -148,6 +148,12 @@ static DEVICE_ATTR(mem_info_vis_vram_used, S_IRUGO,
>>>   static DEVICE_ATTR(mem_info_vram_vendor, S_IRUGO,
>>>   		   amdgpu_mem_info_vram_vendor, NULL);
>>>   
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_vram_total);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_vis_vram_total);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_vram_used);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_vis_vram_used);
>>> +static AMDGPU_DEVICE_ATTR_LIST_NODE(mem_info_vram_vendor);
> Converting all of these individual attributes to an attribute group
> would be a nice thing to do anyway.  Makes your logic much simpler and
> less error-prone.
>
> But again, the driver core should do all of the device file removal
> stuff automatically for you when your PCI device is removed from the
> system _UNLESS_ you are doing crazy things like creating child devices
> or messing with raw kobjects or other horrible things that I haven't
> read the code to see if you are, but hopefully not :)
>
> thanks,
>
> greg k-h