Re: [PATCH 1/7] libcxl: Add debugfs path to CXL context

Dave Jiang
2026-01-09T17:43:19Z

On 1/9/26 9:07 AM, Ben Cheatham wrote:
> Find the CXL debugfs mount point and add it to the CXL library context.
> This will be used by poison and procotol error library functions to
> access the information presented by the filesystem.
>
> Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
> cxl/lib/libcxl.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index 32728de..6b7e92c 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -8,6 +8,8 @@
> #include <stdlib.h>
> #include <dirent.h>
> #include <unistd.h>
> +#include <mntent.h>
> +#include <string.h>
> #include <sys/mman.h>
> #include <sys/stat.h>
> #include <sys/types.h>
> @@ -54,6 +56,7 @@ struct cxl_ctx {
> struct kmod_ctx *kmod_ctx;
> struct daxctl_ctx *daxctl_ctx;
> void *private_data;
> + char *cxl_debugfs;
> };
>
> static void free_pmem(struct cxl_pmem *pmem)
> @@ -240,6 +243,38 @@ CXL_EXPORT void *cxl_get_private_data(struct cxl_ctx *ctx)
> return ctx->private_data;
> }
>
> +static char* get_cxl_debugfs_dir(void)
> +{
> + char *debugfs_dir = NULL;
> + struct mntent *ent;
> + FILE *mntf;
> +
> + mntf = setmntent("/proc/mounts", "r");
> + if (!mntf)
> + return NULL;
> +
> + while ((ent = getmntent(mntf)) != NULL) {
> + if (!strcmp(ent->mnt_type, "debugfs")) {
> + /* Magic '5' here is length of "/cxl" + NULL terminator */
> + debugfs_dir = calloc(strlen(ent->mnt_dir) + 5, 1);
> + if (!debugfs_dir)
> + return NULL;
> +
> + strcpy(debugfs_dir, ent->mnt_dir);
> + strcat(debugfs_dir, "/cxl");
> + if (access(debugfs_dir, F_OK) != 0) {
> + free(debugfs_dir);
> + debugfs_dir = NULL;
> + }
> +
> + break;
> + }
> + }
> +
> + endmntent(mntf);
> + return debugfs_dir;
> +}
> +
> /**
> * cxl_new - instantiate a new library context
> * @ctx: context to establish
> @@ -295,6 +330,7 @@ CXL_EXPORT int cxl_new(struct cxl_ctx **ctx)
> c->udev = udev;
> c->udev_queue = udev_queue;
> c->timeout = 5000;
> + c->cxl_debugfs = get_cxl_debugfs_dir();
>
> return 0;
>
> @@ -350,6 +386,7 @@ CXL_EXPORT void cxl_unref(struct cxl_ctx *ctx)
> kmod_unref(ctx->kmod_ctx);
> daxctl_unref(ctx->daxctl_ctx);
> info(ctx, "context %p released\n", ctx);
> + free((void *)ctx->cxl_debugfs);
> free(ctx);
> }
>