Re: [ndctl PATCH v3 3/7] libcxl: Add poison injection support

["Cheatham, Benjamin" <benjamin.cheatham@amd.com>]

On 10/21/2025 6:44 PM, Dave Jiang wrote:
> 
> 
> On 10/21/25 11:31 AM, Ben Cheatham wrote:
>> Add a library API for clearing and injecting poison into a CXL memory
>> device through the CXL debugfs.
>>
>> This API will be used by the 'cxl-inject-error' and 'cxl-clear-error'
>> commands in later commits.
>>
>> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
>> ---
>>  cxl/lib/libcxl.c   | 60 ++++++++++++++++++++++++++++++++++++++++++++++
>>  cxl/lib/libcxl.sym |  3 +++
>>  cxl/libcxl.h       |  3 +++
>>  3 files changed, 66 insertions(+)
>>
>> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
>> index 9486b0f..9d4bd80 100644
>> --- a/cxl/lib/libcxl.c
>> +++ b/cxl/lib/libcxl.c
>> @@ -5019,3 +5019,63 @@ CXL_EXPORT struct cxl_cmd *cxl_cmd_new_set_alert_config(struct cxl_memdev *memde
>>  {
>>  	return cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_SET_ALERT_CONFIG);
>>  }
>> +
>> +CXL_EXPORT bool cxl_memdev_has_poison_injection(struct cxl_memdev *memdev)
>> +{
>> +	struct cxl_ctx *ctx = memdev->ctx;
>> +	size_t path_len;
>> +	bool exists;
>> +	char *path;
>> +
>> +	if (!ctx->debugfs)
>> +		return false;
>> +
>> +	path_len = strlen(ctx->debugfs) + 100;
>> +	path = calloc(path_len, sizeof(char));
>> +	if (!path)
>> +		return false;
>> +
>> +	snprintf(path, path_len, "%s/cxl/%s/inject_poison", ctx->debugfs,
>> +		 cxl_memdev_get_devname(memdev));
> 
> check return value
> 
>> +	exists = access(path, F_OK) == 0;
> 
> While this works, it is more readable this way:
> 
> 	exists = true;
> 	...
> 	rc = access(path, F_OK);
> 	if (rc)
> 		exists = false;> +

Ok, I'll change it.

>> +	free(path);
>> +	return exists;
>> +}
>> +
>> +static int cxl_memdev_poison_action(struct cxl_memdev *memdev, size_t dpa,
>> +				    bool clear)
>> +{
>> +	struct cxl_ctx *ctx = memdev->ctx;
>> +	size_t path_len;
>> +	char addr[32];
>> +	char *path;
>> +	int rc;
>> +
>> +	if (!ctx->debugfs)
>> +		return -ENOENT;
>> +
>> +	path_len = strlen(ctx->debugfs) + 100;
>> +	path = calloc(path_len, sizeof(char));
>> +	if (!path)
>> +		return -ENOMEM;
>> +
>> +	snprintf(path, path_len, "%s/cxl/%s/%s", ctx->debugfs,
>> +		 cxl_memdev_get_devname(memdev),
>> +		 clear ? "clear_poison" : "inject_poison");
>> +	snprintf(addr, 32, "0x%lx\n", dpa);
> 
> check return values for both snprintf()
> 

Will do!