[PATCH 1/2] cxl/region: fix region leak when attach_target fails in cxl_add_to_region

[Gregory Price]

cxl_add_to_region() ignores the return value of attach_target().  When
attach_target() fails (e.g. cxl_port_setup_targets() returns -ENXIO),
the auto-discovered region remains registered with its HPA resource
consumed but never reaches COMMIT state.  Subsequent region creation
attempts fail with -ENOSPC because the HPA range is already reserved.

Track whether this call to cxl_add_to_region() created the region, and
call drop_region() on attach_target() failure to unregister it and
release the HPA resource.  Pre-existing regions are left alone since
other endpoints may already be attached.

Signed-off-by: Gregory Price <gourry@xxxxxxxxxx>
---
 drivers/cxl/core/region.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 385be9cb44cd..276046d49f88 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3923,6 +3923,7 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 	struct cxl_region_context ctx;
 	struct cxl_region_params *p;
 	bool attach = false;
+	bool newly_created = false;
 	int rc;
 
 	ctx = (struct cxl_region_context) {
@@ -3946,15 +3947,23 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 	mutex_lock(&cxlrd->range_lock);
 	struct cxl_region *cxlr __free(put_cxl_region) =
 		cxl_find_region_by_range(cxlrd, &ctx.hpa_range);
-	if (!cxlr)
+	if (!cxlr) {
 		cxlr = construct_region(cxlrd, &ctx);
+		newly_created = !IS_ERR(cxlr);
+	}
 	mutex_unlock(&cxlrd->range_lock);
 
 	rc = PTR_ERR_OR_ZERO(cxlr);
 	if (rc)
 		return rc;
 
-	attach_target(cxlr, cxled, -1, TASK_UNINTERRUPTIBLE);
+	rc = attach_target(cxlr, cxled, -1, TASK_UNINTERRUPTIBLE);
+	if (rc) {
+		/* If endpoint was just created, tear it down to release HPA */
+		if (newly_created)
+			drop_region(cxlrd, cxlr);
+		return rc;
+	}
 
 	scoped_guard(rwsem_read, &cxl_rwsem.region) {
 		p = &cxlr->params;
@@ -3972,7 +3981,7 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
 				p->res);
 	}
 
-	return rc;
+	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_add_to_region, "CXL");
 
-- 
2.47.3