[PATCH v2 1/2] s390: uv: Fix loop condition in uv_find_secrets

[Steffen Eiden <seiden@linux.ibm.com>]

Nothing modified `start_idx` between the assignment and the comparison,
so the condition was always false and the do/while ran exactly once
even when the UV returned UVC_RC_MORE_DATA. Systems with more than
85 UV secrets got -ENOENT for any secret past the first page.

Fix this by setting the start index at the beginning of the loop not at
the end. First test if there are more secrets left by comparing
start_idx with list->next_secret_idx, and then set the start index to the
next secret index.

Fixes: 7c9137af2042 ("s390/uv: Retrieve UV secrets support")
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/kernel/uv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index a284f98d9716..d970b15ef126 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -781,11 +781,14 @@ int uv_find_secret(const u8 secret_id[UV_SECRET_ID_LEN],
 		   struct uv_secret_list *list,
 		   struct uv_secret_list_item_hdr *secret)
 {
-	u16 start_idx = 0;
+	u16 start_idx;
 	u16 list_rc;
 	int ret;
 
+	list->next_secret_idx = 0;
+
 	do {
+		start_idx = list->next_secret_idx;
 		uv_list_secrets(list, start_idx, &list_rc, NULL);
 		if (list_rc != UVC_RC_EXECUTED && list_rc != UVC_RC_MORE_DATA) {
 			if (list_rc == UVC_RC_INV_CMD)
@@ -796,7 +799,6 @@ int uv_find_secret(const u8 secret_id[UV_SECRET_ID_LEN],
 		ret = find_secret_in_page(secret_id, list, secret);
 		if (ret == 0)
 			return ret;
-		start_idx = list->next_secret_idx;
 	} while (list_rc == UVC_RC_MORE_DATA && start_idx < list->next_secret_idx);
 
 	return -ENOENT;

-- 
2.53.0