cxl/acpi: Cleanup __cxl_parse_cfmws()

As a follow on to the recent rework of __cxl_parse_cfmws() to always
return errors [1], use cleanup.h helpers to remove goto and other cleanups
now that logging is moved to the cxl_parse_cfmws() wrapper.

This ends up adding more code than it deletes, but __cxl_parse_cfmws()
itself does get smaller. The takeaway from the cond_no_free_ptr()
discussion [2] was to not add new macros to handle the cases where
no_free_ptr() is awkward, instead rework the code to have helpers and
clearer delineation of responsibility.

Now one might say that  __free(del_cxl_resource) is excessive given it
is immediately registered with add_or_reset_cxl_resource(). The
rationale for keeping it is that it forces use of "no_free_ptr()" on the
argument passed to add_or_reset_cxl_resource(). That in turn makes it
clear that @res is NULL for the rest of the function which is part of
the point of the cleanup helpers, to turn subtle use after free errors
[3] into loud NULL pointer de-references.

Link: http://lore.kernel.org/r/170820177238.631006.1012639681618409284.stgit@dwillia2-xfh.jf.intel.com [1]
Link: http://lore.kernel.org/r/CAHk-=whBVhnh=KSeBBRet=E7qJAwnPR_aj5em187Q3FiD+LXnA@mail.gmail.com [2]
Link: http://lore.kernel.org/r/[email protected] [3]
Reported-by: Jonathan Cameron <[email protected]>
Closes: http://lore.kernel.org/r/[email protected]
Reviewed-by: Alison Schofield <[email protected]>
Reviewed-by: Vishal Verma <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Link: https://lore.kernel.org/r/171235474028.2718248.14109646123143505522.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dave Jiang <[email protected]>

Author: djbw

drivers/cxl/acpi.c

@@ -316,28 +316,59 @@ static const struct cxl_root_ops acpi_root_ops = {
 	.qos_class = cxl_acpi_qos_class,
 };
 
+static void del_cxl_resource(struct resource *res)
+{
+	if (!res)
+		return;
+	kfree(res->name);
+	kfree(res);
+}
+
+static struct resource *alloc_cxl_resource(resource_size_t base,
+					   resource_size_t n, int id)
+{
+	struct resource *res __free(kfree) = kzalloc(sizeof(*res), GFP_KERNEL);
+
+	if (!res)
+		return NULL;
+
+	res->start = base;
+	res->end = base + n - 1;
+	res->flags = IORESOURCE_MEM;
+	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", id);
+	if (!res->name)
+		return NULL;
+
+	return no_free_ptr(res);
+}
+
+static int add_or_reset_cxl_resource(struct resource *parent, struct resource *res)
+{
+	int rc = insert_resource(parent, res);
+
+	if (rc)
+		del_cxl_resource(res);
+	return rc;
+}
+
+DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
+	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
+DEFINE_FREE(del_cxl_resource, struct resource *, if (_T) del_cxl_resource(_T))
 static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			     struct cxl_cfmws_context *ctx)
 {
 	int target_map[CXL_DECODER_MAX_INTERLEAVE];
 	struct cxl_port *root_port = ctx->root_port;
-	struct resource *cxl_res = ctx->cxl_res;
 	struct cxl_cxims_context cxims_ctx;
-	struct cxl_root_decoder *cxlrd;
 	struct device *dev = ctx->dev;
 	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
-	struct resource *res;
 	int rc;
 
 	rc = cxl_acpi_cfmws_verify(dev, cfmws);
-	if (rc) {
-		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
-			cfmws->base_hpa,
-			cfmws->base_hpa + cfmws->window_size - 1);
+	if (rc)
 		return rc;
-	}
 
 	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
 	if (rc)
@@ -348,38 +379,32 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	for (i = 0; i < ways; i++)
 		target_map[i] = cfmws->interleave_targets[i];
 
-	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	struct resource *res __free(del_cxl_resource) = alloc_cxl_resource(
+		cfmws->base_hpa, cfmws->window_size, ctx->id++);
 	if (!res)
 		return -ENOMEM;
 
-	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
-	if (!res->name)
-		goto err_name;
-
-	res->start = cfmws->base_hpa;
-	res->end = cfmws->base_hpa + cfmws->window_size - 1;
-	res->flags = IORESOURCE_MEM;
-
 	/* add to the local resource tracking to establish a sort order */
-	rc = insert_resource(cxl_res, res);
+	rc = add_or_reset_cxl_resource(ctx->cxl_res, no_free_ptr(res));
 	if (rc)
-		goto err_insert;
+		return rc;
 
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
 		cxl_calc_hb = cxl_hb_modulo;
 	else
 		cxl_calc_hb = cxl_hb_xor;
 
-	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
+	struct cxl_root_decoder *cxlrd __free(put_cxlrd) =
+		cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
 	if (IS_ERR(cxlrd))
 		return PTR_ERR(cxlrd);
 
 	cxld = &cxlrd->cxlsd.cxld;
 	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
 	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 	cxld->hpa_range = (struct range) {
-		.start = res->start,
-		.end = res->end,
+		.start = cfmws->base_hpa,
+		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
 	cxld->interleave_ways = ways;
 	/*
@@ -399,30 +424,20 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
 						   cxl_parse_cxims, &cxims_ctx);
 			if (rc < 0)
-				goto err_xormap;
+				return rc;
 			if (!cxlrd->platform_data) {
 				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
-				rc = -EINVAL;
-				goto err_xormap;
+				return -EINVAL;
 			}
 		}
 	}
 
 	cxlrd->qos_class = cfmws->qtg_id;
 
 	rc = cxl_decoder_add(cxld, target_map);
-err_xormap:
 	if (rc)
-		put_device(&cxld->dev);
-	else
-		rc = cxl_decoder_autoremove(dev, cxld);
-	return rc;
-
-err_insert:
-	kfree(res->name);
-err_name:
-	kfree(res);
-	return -ENOMEM;
+		return rc;
+	return cxl_root_decoder_autoremove(dev, no_free_ptr(cxlrd));
 }
 
 static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
@@ -683,12 +698,6 @@ static void cxl_acpi_lock_reset_class(void *dev)
 	device_lock_reset_class(dev);
 }
 
-static void del_cxl_resource(struct resource *res)
-{
-	kfree(res->name);
-	kfree(res);
-}
-
 static void cxl_set_public_resource(struct resource *priv, struct resource *pub)
 {
 	priv->desc = (unsigned long) pub;

drivers/cxl/cxl.h

@@ -781,6 +781,11 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);
 struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port);
 int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map);
 int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld);
+static inline int cxl_root_decoder_autoremove(struct device *host,
+					      struct cxl_root_decoder *cxlrd)
+{
+	return cxl_decoder_autoremove(host, &cxlrd->cxlsd.cxld);
+}
 int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint);
 
 /**