Re: [ndctl PATCH v2 1/5] libcxl: add interfaces for GET_POISON_LIST mailbox commands

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Sun, 2023-10-01 at 15:31 -0700, alison.schofield@intel.com wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> CXL devices maintain a list of locations that are poisoned or result
> in poison if the addresses are accessed by the host.
> 
> Per the spec (CXL 3.0 8.2.9.8.4.1), the device returns the Poison
> List as a set of  Media Error Records that include the source of the
> error, the starting device physical address and length.
> 
> Trigger the retrieval of the poison list by writing to the memory
> device sysfs attribute: trigger_poison_list. The CXL driver only
> offers triggering per memdev, so the trigger by region interface
> offered here is a convenience API that triggers a poison list
> retrieval for each memdev contributing to a region.
> 
> int cxl_memdev_trigger_poison_list(struct cxl_memdev *memdev);
> int cxl_region_trigger_poison_list(struct cxl_region *region);
> 
> The resulting poison records are logged as kernel trace events
> named 'cxl_poison'.
> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> ---
>  cxl/lib/libcxl.c   | 47 ++++++++++++++++++++++++++++++++++++++++++++++
>  cxl/lib/libcxl.sym |  6 ++++++
>  cxl/libcxl.h       |  2 ++
>  3 files changed, 55 insertions(+)
> 
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index af4ca44eae19..2f6e64ea2ae7 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -1647,6 +1647,53 @@ CXL_EXPORT int cxl_memdev_disable_invalidate(struct cxl_memdev *memdev)
>         return 0;
>  }
>  
> +CXL_EXPORT int cxl_memdev_trigger_poison_list(struct cxl_memdev *memdev)
> +{
> +       struct cxl_ctx *ctx = cxl_memdev_get_ctx(memdev);
> +       char *path = memdev->dev_buf;
> +       int len = memdev->buf_len, rc;
> +
> +       if (snprintf(path, len, "%s/trigger_poison_list", memdev->dev_path) >=
> +           len) {

I see this unfortunate line break Jonathan commented on still crept in,
agreed that breaking up snprintf's args would look better.