RE: [ndctl PATCH v2 1/4] ndctl: add CXL bus detection

[Dan Williams <dan.j.williams@intel.com>]

Dave Jiang wrote:
> Add a CXL bus type, and detect whether a 'dimm' is backed by the CXL
> subsystem.
> 
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> 
> ---
> v2:
> - Improve commit log. (Vishal)
> ---
>  ndctl/lib/libndctl.c   |   53 ++++++++++++++++++++++++++++++++++++++++++++++++
>  ndctl/lib/libndctl.sym |    1 +
>  ndctl/lib/private.h    |    1 +
>  ndctl/libndctl.h       |    1 +
>  4 files changed, 56 insertions(+)
> 
> diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
> index ad54f0626510..10422e24d38b 100644
> --- a/ndctl/lib/libndctl.c
> +++ b/ndctl/lib/libndctl.c
> @@ -12,6 +12,7 @@
>  #include <ctype.h>
>  #include <fcntl.h>
>  #include <dirent.h>
> +#include <libgen.h>

This new include had me looking for why below...

>  #include <sys/stat.h>
>  #include <sys/types.h>
>  #include <sys/ioctl.h>
> @@ -876,6 +877,48 @@ static enum ndctl_fwa_method fwa_method_to_method(const char *fwa_method)
>  	return NDCTL_FWA_METHOD_RESET;
>  }
>  
> +static int is_ndbus_cxl(const char *ctl_base)
> +{
> +	char *path, *ppath, *subsys;
> +	char tmp_path[PATH_MAX];
> +	int rc;
> +
> +	/* get the real path of ctl_base */
> +	path = realpath(ctl_base, NULL);
> +	if (!path)
> +		return -errno;
> +
> +	/* setup to get the nd bridge device backing the ctl */
> +	sprintf(tmp_path, "%s/device", path);
> +	free(path);
> +
> +	path = realpath(tmp_path, NULL);
> +	if (!path)
> +		return -errno;
> +
> +	/* get the parent dir of the ndbus, which should be the nvdimm-bridge */
> +	ppath = dirname(path);
> +
> +	/* setup to get the subsystem of the nvdimm-bridge */
> +	sprintf(tmp_path, "%s/%s", ppath, "subsystem");
> +	free(path);
> +
> +	path = realpath(tmp_path, NULL);
> +	if (!path)
> +		return -errno;
> +
> +	subsys = basename(path);
> +
> +	/* check if subsystem is cxl */
> +	if (!strcmp(subsys, "cxl"))
> +		rc = 1;
> +	else
> +		rc = 0;
> +
> +	free(path);
> +	return rc;
> +}
> +
>  static void *add_bus(void *parent, int id, const char *ctl_base)
>  {
>  	char buf[SYSFS_ATTR_SIZE];
> @@ -919,6 +962,11 @@ static void *add_bus(void *parent, int id, const char *ctl_base)
>  	else
>  		bus->has_of_node = 1;
>  
> +	if (is_ndbus_cxl(ctl_base))
> +		bus->has_cxl = 1;
> +	else
> +		bus->has_cxl = 0;
> +

I think you can drop is_ndbus_cxl() and just do this:

@@ -981,6 +976,11 @@ static void *add_bus(void *parent, int id, const char *ctl_base)
        if (!bus->provider)
                goto err_read;
 
+       if (strcasestr("cxl", provider))
+               bus->has_cxl = 1;
+       else
+               bus->has_cxl = 0;
+
        sprintf(path, "%s/device/wait_probe", ctl_base);
        bus->wait_probe_path = strdup(path);
        if (!bus->wait_probe_path)