[PATCH v3 5/7] cxl/core: Use guard() to drop goto pattern of cxl_dpa_alloc()

[Li Ming <ming.li@zohomail.com>]

In cxl_dpa_alloc(), some checking and operations need to be protected by
a rwsem called cxl_dpa_rwsem, so there is a goto pattern in
cxl_dpa_alloc() to release the rwsem. The goto pattern can be optimized
by using guard() to hold the rwsem.

Creating a new function called __cxl_dpa_alloc() to include all checking
and operations needed to be protected by cxl_dpa_rwsem. Using
guard(rwsem_write()) to hold cxl_dpa_rwsem at the beginning of the new
function.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Li Ming <ming.li@zohomail.com>
---
 drivers/cxl/core/hdm.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index e1d1fe5492ff..70cae4ebf8a4 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -603,36 +603,32 @@ int cxl_dpa_set_part(struct cxl_endpoint_decoder *cxled,
 	return 0;
 }
 
-int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size)
+static int __cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size)
 {
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-	struct cxl_port *port = cxled_to_port(cxled);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct device *dev = &cxled->cxld.dev;
 	struct resource *res, *prev = NULL;
 	resource_size_t start, avail, skip, skip_start;
 	struct resource *p, *last;
-	int part, rc;
+	int part;
 
-	down_write(&cxl_dpa_rwsem);
+	guard(rwsem_write)(&cxl_dpa_rwsem);
 	if (cxled->cxld.region) {
 		dev_dbg(dev, "decoder attached to %s\n",
 			dev_name(&cxled->cxld.region->dev));
-		rc = -EBUSY;
-		goto out;
+		return -EBUSY;
 	}
 
 	if (cxled->cxld.flags & CXL_DECODER_F_ENABLE) {
 		dev_dbg(dev, "decoder enabled\n");
-		rc = -EBUSY;
-		goto out;
+		return -EBUSY;
 	}
 
 	part = cxled->part;
 	if (part < 0) {
 		dev_dbg(dev, "partition not set\n");
-		rc = -EBUSY;
-		goto out;
+		return -EBUSY;
 	}
 
 	res = &cxlds->part[part].res;
@@ -672,14 +668,18 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size)
 	if (size > avail) {
 		dev_dbg(dev, "%pa exceeds available %s capacity: %pa\n", &size,
 			res->name, &avail);
-		rc = -ENOSPC;
-		goto out;
+		return -ENOSPC;
 	}
 
-	rc = __cxl_dpa_reserve(cxled, start, size, skip);
-out:
-	up_write(&cxl_dpa_rwsem);
+	return __cxl_dpa_reserve(cxled, start, size, skip);
+}
+
+int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size)
+{
+	struct cxl_port *port = cxled_to_port(cxled);
+	int rc;
 
+	rc = __cxl_dpa_alloc(cxled, size);
 	if (rc)
 		return rc;
 
-- 
2.34.1