[PATCH 3/3] cxl/region: Fix state transitions after reset failure

[Dan Williams <dan.j.williams@intel.com>]

Jonathan reports that failed attempts to reset a region (teardown its
HDM decoder configuration) mistakenly advance the state of the region
to "not committed". Revert to the previous state of the region on reset
failure so that the reset can be re-attempted.

Reported-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Closes: http://lore.kernel.org/r/20230316171441.0000205b@Huawei.com
Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/core/region.c |   26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 31f498f0fb3a..38db377e13f1 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -296,9 +296,11 @@ static ssize_t commit_store(struct device *dev, struct device_attribute *attr,
 	if (rc)
 		return rc;
 
-	if (commit)
+	if (commit) {
 		rc = cxl_region_decode_commit(cxlr);
-	else {
+		if (rc == 0)
+			p->state = CXL_CONFIG_COMMIT;
+	} else {
 		p->state = CXL_CONFIG_RESET_PENDING;
 		up_write(&cxl_region_rwsem);
 		device_release_driver(&cxlr->dev);
@@ -308,18 +310,20 @@ static ssize_t commit_store(struct device *dev, struct device_attribute *attr,
 		 * The lock was dropped, so need to revalidate that the reset is
 		 * still pending.
 		 */
-		if (p->state == CXL_CONFIG_RESET_PENDING)
+		if (p->state == CXL_CONFIG_RESET_PENDING) {
 			rc = cxl_region_decode_reset(cxlr, p->interleave_ways);
+			/*
+			 * Revert to committed since there may still be active
+			 * decoders associated with this region, or move forward
+			 * to active to mark the reset successful
+			 */
+			if (rc)
+				p->state = CXL_CONFIG_COMMIT;
+			else
+				p->state = CXL_CONFIG_ACTIVE;
+		}
 	}
 
-	if (rc)
-		goto out;
-
-	if (commit)
-		p->state = CXL_CONFIG_COMMIT;
-	else if (p->state == CXL_CONFIG_RESET_PENDING)
-		p->state = CXL_CONFIG_ACTIVE;
-
 out:
 	up_write(&cxl_region_rwsem);