Patch "cxl/region: Convert cxl_pmem_region_alloc to scope-based resource management" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    cxl/region: Convert cxl_pmem_region_alloc to scope-based resource management

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cxl-region-convert-cxl_pmem_region_alloc-to-scope-ba.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4512fababe29c692c143ee5936e130fda19d254b
Author: Dan Williams <dan.j.williams@xxxxxxxxx>
Date:   Tue Apr 30 14:59:00 2024 -0700

    cxl/region: Convert cxl_pmem_region_alloc to scope-based resource management
    
    [ Upstream commit d357dd8ad2f154376e5cb930284e7bf4fe21ffaa ]
    
    A recent bugfix to cxl_pmem_region_alloc() to fix an
    error-unwind-memleak [1], highlighted a use case for scope-based resource
    management.
    
    Delete the goto for releasing @cxl_region_rwsem, and return error codes
    directly from error condition paths.
    
    The caller, devm_cxl_add_pmem_region(), is no longer given @cxlr_pmem
    directly it must retrieve it from @cxlr->cxlr_pmem. This retrieval from
    @cxlr was already in place for @cxlr->cxl_nvb, and converting
    cxl_pmem_region_alloc() to return an int makes it less awkward to handle
    no_free_ptr().
    
    Cc: Li Zhijian <lizhijian@xxxxxxxxxxx>
    Reported-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
    Closes: http://lore.kernel.org/r/20240430174540.000039ce@xxxxxxxxxx
    Link: http://lore.kernel.org/r/20240428030748.318985-1-lizhijian@xxxxxxxxxxx
    Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
    Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/171451430965.1147997.15782562063090960666.stgit@xxxxxxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
    Stable-dep-of: 84ec985944ef ("cxl/mem: Fix no cxl_nvd during pmem region auto-assembling")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 18b95149640b6..bcb30e04e0963 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2681,26 +2681,21 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port)
 
 static struct lock_class_key cxl_pmem_region_key;
 
-static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
+static int cxl_pmem_region_alloc(struct cxl_region *cxlr)
 {
 	struct cxl_region_params *p = &cxlr->params;
 	struct cxl_nvdimm_bridge *cxl_nvb;
-	struct cxl_pmem_region *cxlr_pmem;
 	struct device *dev;
 	int i;
 
-	down_read(&cxl_region_rwsem);
-	if (p->state != CXL_CONFIG_COMMIT) {
-		cxlr_pmem = ERR_PTR(-ENXIO);
-		goto out;
-	}
+	guard(rwsem_read)(&cxl_region_rwsem);
+	if (p->state != CXL_CONFIG_COMMIT)
+		return -ENXIO;
 
-	cxlr_pmem = kzalloc(struct_size(cxlr_pmem, mapping, p->nr_targets),
-			    GFP_KERNEL);
-	if (!cxlr_pmem) {
-		cxlr_pmem = ERR_PTR(-ENOMEM);
-		goto out;
-	}
+	struct cxl_pmem_region *cxlr_pmem __free(kfree) =
+		kzalloc(struct_size(cxlr_pmem, mapping, p->nr_targets), GFP_KERNEL);
+	if (!cxlr_pmem)
+		return -ENOMEM;
 
 	cxlr_pmem->hpa_range.start = p->res->start;
 	cxlr_pmem->hpa_range.end = p->res->end;
@@ -2718,11 +2713,8 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
 		 */
 		if (i == 0) {
 			cxl_nvb = cxl_find_nvdimm_bridge(cxlmd);
-			if (!cxl_nvb) {
-				kfree(cxlr_pmem);
-				cxlr_pmem = ERR_PTR(-ENODEV);
-				goto out;
-			}
+			if (!cxl_nvb)
+				return -ENODEV;
 			cxlr->cxl_nvb = cxl_nvb;
 		}
 		m->cxlmd = cxlmd;
@@ -2733,18 +2725,16 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
 	}
 
 	dev = &cxlr_pmem->dev;
-	cxlr_pmem->cxlr = cxlr;
-	cxlr->cxlr_pmem = cxlr_pmem;
 	device_initialize(dev);
 	lockdep_set_class(&dev->mutex, &cxl_pmem_region_key);
 	device_set_pm_not_required(dev);
 	dev->parent = &cxlr->dev;
 	dev->bus = &cxl_bus_type;
 	dev->type = &cxl_pmem_region_type;
-out:
-	up_read(&cxl_region_rwsem);
+	cxlr_pmem->cxlr = cxlr;
+	cxlr->cxlr_pmem = no_free_ptr(cxlr_pmem);
 
-	return cxlr_pmem;
+	return 0;
 }
 
 static void cxl_dax_region_release(struct device *dev)
@@ -2861,9 +2851,10 @@ static int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
 	struct device *dev;
 	int rc;
 
-	cxlr_pmem = cxl_pmem_region_alloc(cxlr);
-	if (IS_ERR(cxlr_pmem))
-		return PTR_ERR(cxlr_pmem);
+	rc = cxl_pmem_region_alloc(cxlr);
+	if (rc)
+		return rc;
+	cxlr_pmem = cxlr->cxlr_pmem;
 	cxl_nvb = cxlr->cxl_nvb;
 
 	dev = &cxlr_pmem->dev;