Re: [PATCH v4 1/7] libcxl: Add debugfs path to CXL context

[Dave Jiang <dave.jiang@intel.com>]

On 12/9/25 10:13 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>
> ---
>  cxl/lib/libcxl.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
> index cafde1c..3718b76 100644
> --- a/cxl/lib/libcxl.c
> +++ b/cxl/lib/libcxl.c
> @@ -54,6 +54,7 @@ struct cxl_ctx {
>  	struct kmod_ctx *kmod_ctx;
>  	struct daxctl_ctx *daxctl_ctx;
>  	void *private_data;
> +	const char *debugfs;
>  };
>  
>  static void free_pmem(struct cxl_pmem *pmem)
> @@ -240,6 +241,43 @@ CXL_EXPORT void *cxl_get_private_data(struct cxl_ctx *ctx)
>  	return ctx->private_data;
>  }
>  
> +static const char *get_debugfs_dir(void)

I would suggest taking a look at setmntent()/getmntent() usages. Probably easier than trying to open code this and do it yourself here. You should be able to pass "/proc/mounts" to setmntent() and then do everything through a loop of getmntent().

DJ

> +{
> +	char *dev, *dir, *type, *debugfs_dir = NULL;
> +	char line[PATH_MAX + 256 + 1];
> +	FILE *fp;
> +
> +	fp = fopen("/proc/mounts", "r");
> +	if (!fp)
> +		return debugfs_dir;
> +
> +	while (fgets(line, sizeof(line), fp)) {
> +		dev = strtok(line, " \t");
> +		if (!dev)
> +			break;
> +
> +		dir = strtok(NULL, " \t");
> +		if (!dir)
> +			break;
> +
> +		type = strtok(NULL, " \t");
> +		if (!type)
> +			break;
> +
> +		if (!strcmp(type, "debugfs")) {
> +			debugfs_dir = calloc(strlen(dir) + 1, 1);
> +			if (!debugfs_dir)
> +				break;
> +
> +			strcpy(debugfs_dir, dir);
> +			break;
> +		}
> +	}
> +
> +	fclose(fp);
> +	return debugfs_dir;
> +}
> +
>  /**
>   * cxl_new - instantiate a new library context
>   * @ctx: context to establish
> @@ -295,6 +333,7 @@ CXL_EXPORT int cxl_new(struct cxl_ctx **ctx)
>  	c->udev = udev;
>  	c->udev_queue = udev_queue;
>  	c->timeout = 5000;
> +	c->debugfs = get_debugfs_dir();
>  
>  	return 0;
>  
> @@ -350,6 +389,7 @@ 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->debugfs);
>  	free(ctx);
>  }
>