netdev - Re: [PATCH v18 06/20] cxl: Prepare memdev creation for type2

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Message-ID: <bfcc6933-2106-4332-ba6b-fca8d7a32561@amd.com>
Date: Wed, 24 Sep 2025 09:44:00 +0100
From: Alejandro Lucero Palau <alucerop@....com>
To: "Cheatham, Benjamin" <benjamin.cheatham@....com>,
 alejandro.lucero-palau@....com
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Alison Schofield <alison.schofield@...el.com>, linux-cxl@...r.kernel.org,
 netdev@...r.kernel.org, dan.j.williams@...el.com, edward.cree@....com,
 davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 edumazet@...gle.com, dave.jiang@...el.com
Subject: Re: [PATCH v18 06/20] cxl: Prepare memdev creation for type2


On 9/22/25 22:10, Cheatham, Benjamin wrote:
> On 9/18/2025 4:17 AM, alejandro.lucero-palau@....com wrote:
>> From: Alejandro Lucero <alucerop@....com>
>>
>> Current cxl core is relying on a CXL_DEVTYPE_CLASSMEM type device when
>> creating a memdev leading to problems when obtaining cxl_memdev_state
>> references from a CXL_DEVTYPE_DEVMEM type.
>>
>> Modify check for obtaining cxl_memdev_state adding CXL_DEVTYPE_DEVMEM
>> support.
>>
>> Make devm_cxl_add_memdev accessible from a accel driver.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>
>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
>> Reviewed-by: Alison Schofield <alison.schofield@...el.com>
>> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
>> ---
> [snip]
>
>> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
>> index 7480dfdbb57d..9ffee09fcb50 100644
>> --- a/drivers/cxl/mem.c
>> +++ b/drivers/cxl/mem.c
>> @@ -67,6 +67,26 @@ static int cxl_debugfs_poison_clear(void *data, u64 dpa)
>>   DEFINE_DEBUGFS_ATTRIBUTE(cxl_poison_clear_fops, NULL,
>>   			 cxl_debugfs_poison_clear, "%llx\n");
>>   
>> +static void cxl_memdev_poison_enable(struct cxl_memdev_state *mds,
>> +				     struct cxl_memdev *cxlmd,
>> +				     struct dentry *dentry)
>> +{
>> +	/*
>> +	 * Avoid poison debugfs for DEVMEM aka accelerators as they rely on
>> +	 * cxl_memdev_state.
>> +	 */
>> +	if (!mds)
>> +		return;
>> +
>> +	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
>> +		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
>> +				    &cxl_poison_inject_fops);
>> +
>> +	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
>> +		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
>> +				    &cxl_poison_clear_fops);
>> +}
>> +
>>   static int cxl_mem_probe(struct device *dev)
>>   {
>>   	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
>> @@ -94,12 +114,8 @@ static int cxl_mem_probe(struct device *dev)
>>   	dentry = cxl_debugfs_create_dir(dev_name(dev));
>>   	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);
>>   
>> -	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
>> -		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
>> -				    &cxl_poison_inject_fops);
>> -	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
>> -		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
>> -				    &cxl_poison_clear_fops);
>> +	/* for CLASSMEM memory expanders enable poison injection */
> Nit: I don't think you need the comment here and in the function itself. I would
> go with the one in the function personally, but either should be fine imo.


Right. I'll fix it.


Thanks!