iscsi-scstd: Clarify result handling and connection cleanup

Checkpatch reports:
  ASSIGN_IN_IF: do not use assignment in if condition
  DEEP_INDENTATION: Too many leading tabs - consider code refactoring
  USE_NEGATIVE_ERRNO: return of an errno should typically be negative
    (ie: return -EAGAIN)

Separate status assignments from simple if conditions and preserve
short-circuit dispatch bounds. Leave the parameter-dispatch else-if
chains and their lookup precedence intact.

Flatten incoming-connection cleanup with early continues. Keep the CLOSE
case, kernel-owned destruction, session-count rollback and empty-session
release in their original order; no new ownership transfer is
introduced.

Return -EAGAIN for an empty nonblocking event queue. The drain loop
checks zero versus nonzero, while main-loop callers discard this result.
Retain EINTR retry and event draining behavior and document the return
convention.

iscsi-scst/usr/event.c

@@ -520,7 +520,8 @@ static int handle_e_get_attr_value(int fd, const struct iscsi_kern_event *event)
 
 	p = buf;
 	pp = config_sep_string(&p);
-	if (!((idx = params_index_by_name(pp, target_keys)) < 0)) {
+	idx = params_index_by_name(pp, target_keys);
+	if (idx >= 0) {
 		if (target == NULL) {
 			log_error("Target expected for attr %s", pp);
 			res = -EINVAL;
@@ -850,7 +851,8 @@ static int handle_e_set_attr_value(int fd, const struct iscsi_kern_event *event)
 
 	p = buf;
 	pp = config_sep_string(&p);
-	if (!((idx = params_index_by_name(pp, target_keys)) < 0)) {
+	idx = params_index_by_name(pp, target_keys);
+	if (idx >= 0) {
 		struct iscsi_param params[target_key_last];
 		struct session *session;
 
@@ -1184,6 +1186,7 @@ out_free_server:
 }
 
 
+/* Return zero after handling an event, or -EAGAIN when no event is available. */
 int handle_iscsi_events(int fd, bool wait)
 {
 	struct session *session;
@@ -1200,9 +1203,10 @@ int handle_iscsi_events(int fd, bool wait)
 	STATIC_ASSERT(sizeof(event) % NLMSG_ALIGNTO == 0);
 
 retry:
-	if ((rc = nl_read(fd, &event, sizeof(event), wait)) < 0) {
+	rc = nl_read(fd, &event, sizeof(event), wait);
+	if (rc < 0) {
 		if (errno == EAGAIN)
-			return EAGAIN;
+			return -EAGAIN;
 		if (errno == EINTR)
 			goto retry;
 		log_error("read netlink fd (%d) failed: %s", fd, strerror(errno));

iscsi-scst/usr/iscsi_adm.c

@@ -334,9 +334,9 @@ static int trgt_handle(int op, u32 set, u32 tid, char *params)
 	switch (op) {
 	case OP_NEW:
 	{
-		char *p = params;
+		char *p = params ? strchr(params, '=') : NULL;
 
-		if (!params || !(p = strchr(params, '='))) {
+		if (!p) {
 			fprintf(stderr, "Target name required\n");
 			err = -EINVAL;
 			goto out;
@@ -356,7 +356,8 @@ static int trgt_handle(int op, u32 set, u32 tid, char *params)
 		break;
 	case OP_UPDATE:
 		req.rcmnd = C_TRGT_UPDATE;
-		if ((err = parse_trgt_params(&req.u.trgt, params)) < 0)
+		err = parse_trgt_params(&req.u.trgt, params);
+		if (err < 0)
 			goto out;
 		break;
 	case OP_SHOW:

iscsi-scst/usr/iscsi_scstd.c

@@ -760,6 +760,7 @@ static void event_loop(void)
 		for (i = 0; i < INCOMING_MAX; i++) {
 			struct connection *conn = incoming[i];
 			struct pollfd *pollfd = &poll_array[POLL_INCOMING + i];
+			struct session *sess;
 
 			if (!conn || !pollfd->revents)
 				continue;
@@ -768,39 +769,38 @@ static void event_loop(void)
 
 			event_conn(conn, pollfd);
 
-			if ((conn->state == STATE_CLOSE) ||
-			    (conn->state == STATE_EXIT) ||
-			    (conn->state == STATE_DROP)) {
-				struct session *sess = conn->sess;
+			if (conn->state != STATE_CLOSE &&
+			    conn->state != STATE_EXIT &&
+			    conn->state != STATE_DROP)
+				continue;
 
-				log_debug(1, "closing conn %p state=0x%x fd=%u",
-					  conn, conn->state, pollfd->fd);
-				conn_free_pdu(conn);
-				close(pollfd->fd);
-				pollfd->fd = -1;
-				incoming[i] = NULL;
-				incoming_cnt--;
-				if (conn->state != STATE_CLOSE) {
-					if (conn->passed_to_kern) {
-						kernel_conn_destroy(conn->tid,
-							conn->sess->sid.id64,
-							conn->cid);
-					} else {
-						/*
-						 * Check if session could not be established,
-						 * but sessions count was already incremented
-						 */
-						if (!sess && conn->sessions_count_incremented)
-							conn->target->sessions_count--;
-						log_debug(1, "conn %p freed (sess %p, empty %d)",
-							conn, sess,
-							sess ? list_empty(&sess->conn_list) : -1);
-						conn_free(conn);
-						if (sess && list_empty(&sess->conn_list))
-							session_free(sess);
-					}
-				}
+			sess = conn->sess;
+			log_debug(1, "closing conn %p state=0x%x fd=%u",
+				  conn, conn->state, pollfd->fd);
+			conn_free_pdu(conn);
+			close(pollfd->fd);
+			pollfd->fd = -1;
+			incoming[i] = NULL;
+			incoming_cnt--;
+			if (conn->state == STATE_CLOSE)
+				continue;
+
+			if (conn->passed_to_kern) {
+				kernel_conn_destroy(conn->tid, conn->sess->sid.id64, conn->cid);
+				continue;
 			}
+
+			/*
+			 * The count may have been incremented before session
+			 * establishment failed.
+			 */
+			if (!sess && conn->sessions_count_incremented)
+				conn->target->sessions_count--;
+			log_debug(1, "conn %p freed (sess %p, empty %d)",
+				  conn, sess, sess ? list_empty(&sess->conn_list) : -1);
+			conn_free(conn);
+			if (sess && list_empty(&sess->conn_list))
+				session_free(sess);
 		}
 	}
 }

iscsi-scst/usr/iscsid.c

@@ -1162,7 +1162,8 @@ static void cmnd_exec_login(struct connection *conn)
 			switch (conn->state) {
 			case STATE_SECURITY:
 			case STATE_SECURITY_DONE:
-				if ((nsg_disagree = text_check_params(conn))) {
+				nsg_disagree = text_check_params(conn);
+				if (nsg_disagree) {
 					conn->state = STATE_LOGIN;
 					nsg = ISCSI_FLG_NSG_LOGIN;
 					break;