[PATCHv3 2/4] block/sed: Add helper to qualify response tokens

[Jon Derrick]

Add helper which verifies the response token is valid and matches the
expected value. Merges token_type and response_get_token.

Signed-off-by: Jon Derrick <jonathan.derr...@intel.com>
---
 block/sed-opal.c | 61 +++++++++++++++++++++++---------------------------------
 1 file changed, 25 insertions(+), 36 deletions(-)

diff --git a/block/sed-opal.c b/block/sed-opal.c
index 77623ad..d6dd604 100644
--- a/block/sed-opal.c
+++ b/block/sed-opal.c
@@ -591,48 +591,25 @@ static int cmd_finalize(struct opal_dev *cmd, u32 hsn, 
u32 tsn)
        return 0;
 }
 
-static enum opal_response_token token_type(const struct parsed_resp *resp,
-                                          int n)
+static const struct opal_resp_tok *response_get_token(
+                               const struct parsed_resp *resp,
+                               int n)
 {
        const struct opal_resp_tok *tok;
 
        if (n >= resp->num) {
                pr_err("Token number doesn't exist: %d, resp: %d\n",
                       n, resp->num);
-               return OPAL_DTA_TOKENID_INVALID;
+               return ERR_PTR(-EINVAL);
        }
 
        tok = &resp->toks[n];
        if (tok->len == 0) {
                pr_err("Token length must be non-zero\n");
-               return OPAL_DTA_TOKENID_INVALID;
+               return ERR_PTR(-EINVAL);
        }
 
-       return tok->type;
-}
-
-/*
- * This function returns 0 in case of invalid token. One should call
- * token_type() first to find out if the token is valid or not.
- */
-static enum opal_token response_get_token(const struct parsed_resp *resp,
-                                         int n)
-{
-       const struct opal_resp_tok *tok;
-
-       if (n >= resp->num) {
-               pr_err("Token number doesn't exist: %d, resp: %d\n",
-                      n, resp->num);
-               return 0;
-       }
-
-       tok = &resp->toks[n];
-       if (tok->len == 0) {
-               pr_err("Token length must be non-zero\n");
-               return 0;
-       }
-
-       return tok->pos[0];
+       return tok;
 }
 
 static ssize_t response_parse_tiny(struct opal_resp_tok *tok,
@@ -851,20 +828,32 @@ static u64 response_get_u64(const struct parsed_resp 
*resp, int n)
        return resp->toks[n].stored.u;
 }
 
+static bool response_token_matches(const struct opal_resp_tok *token, u8 match)
+{
+       if (IS_ERR_OR_NULL(token) ||
+           token->type != OPAL_DTA_TOKENID_TOKEN ||
+           token->pos[0] != match)
+               return false;
+       return true;
+}
+
 static u8 response_status(const struct parsed_resp *resp)
 {
-       if (token_type(resp, 0) == OPAL_DTA_TOKENID_TOKEN &&
-           response_get_token(resp, 0) == OPAL_ENDOFSESSION) {
+       const struct opal_resp_tok *tok;
+
+       tok = response_get_token(resp, 0);
+       if (response_token_matches(tok, OPAL_ENDOFSESSION))
                return 0;
-       }
 
        if (resp->num < 5)
                return DTAERROR_NO_METHOD_STATUS;
 
-       if (token_type(resp, resp->num - 1) != OPAL_DTA_TOKENID_TOKEN ||
-           token_type(resp, resp->num - 5) != OPAL_DTA_TOKENID_TOKEN ||
-           response_get_token(resp, resp->num - 1) != OPAL_ENDLIST ||
-           response_get_token(resp, resp->num - 5) != OPAL_STARTLIST)
+       tok = response_get_token(resp, resp->num - 5);
+       if (!response_token_matches(tok, OPAL_STARTLIST))
+               return DTAERROR_NO_METHOD_STATUS;
+
+       tok = response_get_token(resp, resp->num - 1);
+       if (!response_token_matches(tok, OPAL_ENDLIST))
                return DTAERROR_NO_METHOD_STATUS;
 
        return response_get_u64(resp, resp->num - 4);
-- 
1.8.3.1