ACPI / APEI: Fix the returned value in erst_dbg_read

If the persistent store is empty initially, the function 'erst_dbg_read'
returns a nonzero value. The better way is to return a zero indicating the
read operation reaches EOF.

Tested on two different servers.

Signed-off-by: Adrian Huang <adrian.huang@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/acpi/apei/erst-dbg.c b/drivers/acpi/apei/erst-dbg.c
index 903549df809b..04ab5c9d3ced 100644
--- a/drivers/acpi/apei/erst-dbg.c
+++ b/drivers/acpi/apei/erst-dbg.c
@@ -111,8 +111,17 @@ retry_next:
         if (rc)
                 goto out;
         /* no more record */
-        if (id == APEI_ERST_INVALID_RECORD_ID)
+        if (id == APEI_ERST_INVALID_RECORD_ID) {
+                /*
+                 * If the persistent store is empty initially, the function
+                 * 'erst_read' below will return "-ENOENT" value. This causes
+                 * 'retry_next' label is entered again. The returned value
+                 * should be zero indicating the read operation is EOF.
+                 */
+                len = 0;
+
                 goto out;
+        }
 retry:
         rc = len = erst_read(id, erst_dbg_buf, erst_dbg_buf_len);
         /* The record may be cleared by others, try read next record */