[PATCH 6.4 536/800] cxl/region: Fix state transitions after reset failure

Greg Kroah-Hartman
2023-07-16T20:19:18Z

From: Dan Williams <dan.j.williams@intel.com>

[ Upstream commit adfe19738b71a893da62cb2e30bd6bdb4299ea67 ]

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")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/168696507968.3590522.14484000711718573626.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 fa29bd2ec3227..bfdd424d68970 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);

--
2.39.2