[PATCH V6 09/10] cxl/mem: Retry reading CDAT on failure

ira.weiny
2022-02-01T07:20:34Z

From: Ira Weiny <ira.weiny@intel.com>

The CDAT read may fail for a number of reasons but mainly it is possible
to get different parts of a valid state. The checksum in the CDAT table
protects against this.

Now that the checksum is validated issue a retry if the CDAT read fails.
For now 2 retries are implemented.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
NOTE: Is 2 enough? Should this just be delayed until the time when the
data is actually needed and not there?

Changes from V5:
New patch -- easy to push off or drop.
---
drivers/cxl/core/memdev.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index a01068e98333..11d721c56f08 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -356,7 +356,8 @@ static const struct file_operations cxl_memdev_fops = {
.llseek = noop_llseek,
};

-static int read_cdat_data(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds)
+static int __read_cdat_data(struct cxl_memdev *cxlmd,
+ struct cxl_dev_state *cxlds)
{
struct device *dev = &cxlmd->dev;
size_t cdat_length;
@@ -371,6 +372,20 @@ static int read_cdat_data(struct cxl_memdev *cxlmd, struct cxl_dev_state *cxlds)
return cxl_mem_cdat_read_table(cxlds, &cxlmd->cdat);
}

+static int read_cdat_data(struct cxl_memdev *cxlmd,
+ struct cxl_dev_state *cxlds)
+{
+ int retries = 2;
+ int rc;
+
+ while (--retries) {
+ rc = __read_cdat_data(cxlmd, cxlds);
+ if (!rc)
+ break;
+ }
+ return rc;
+}
+
struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds)
{
struct cxl_memdev *cxlmd;
--
2.31.1