drivers: modem: replace K_SPINLOCK macro with explicit locking where needed

This PR is related to the following Zephyr PR:
zephyrproject-rtos#81431
Some compilers (e.g. arm-zephyr-eabi-gcc) don't understand
the K_SPINLOCK() macro and therefore do warn about
uninitialized variables in the modem related modules.
Fix: Replaced the K_SPINLOCK macro with explicit k_spin_lock/k_spin_unlock calls
only at relevant locations in the modem subsystem.

Signed-off-by: Fabian Kainka <[email protected]>

Author: FKainka

subsys/modem/modem_cmux.c

@@ -1108,25 +1108,26 @@ static int modem_cmux_dlci_pipe_api_transmit(void *data, const uint8_t *buf, siz
 {
 	struct modem_cmux_dlci *dlci = (struct modem_cmux_dlci *)data;
 	struct modem_cmux *cmux = dlci->cmux;
-	int ret = 0;
+	int ret;
 
-	K_SPINLOCK(&cmux->work_lock) {
-		if (!cmux->attached) {
-			ret = -EPERM;
-			K_SPINLOCK_BREAK;
-		}
+	k_spinlock_key_t key = k_spin_lock(&cmux->work_lock);
+	if (!cmux->attached) {
+		ret = -EPERM;
+		k_spin_unlock(&cmux->work_lock, key);
+		return ret;
+	}
 
-		struct modem_cmux_frame frame = {
-			.dlci_address = dlci->dlci_address,
-			.cr = true,
-			.pf = false,
-			.type = MODEM_CMUX_FRAME_TYPE_UIH,
-			.data = buf,
-			.data_len = size,
-		};
+	struct modem_cmux_frame frame = {
+		.dlci_address = dlci->dlci_address,
+		.cr = true,
+		.pf = false,
+		.type = MODEM_CMUX_FRAME_TYPE_UIH,
+		.data = buf,
+		.data_len = size,
+	};
 
-		ret = modem_cmux_transmit_data_frame(cmux, &frame);
-	}
+	ret = modem_cmux_transmit_data_frame(cmux, &frame);
+	k_spin_unlock(&cmux->work_lock, key);
 
 	return ret;
 }

subsys/modem/modem_pipelink.c

@@ -29,9 +29,9 @@ bool modem_pipelink_is_connected(struct modem_pipelink *link)
 {
 	bool connected;
 
-	K_SPINLOCK(&link->spinlock) {
-		connected = link->connected;
-	}
+	k_spinlock_key_t key = k_spin_lock(&link->spinlock);
+	connected = link->connected;
+	k_spin_unlock(&link->spinlock, key);
 
 	return connected;
 }

subsys/modem/modem_stats.c

@@ -32,22 +32,22 @@ static void stats_buffer_list_append(struct modem_stats_buffer *buffer)
 
 static struct modem_stats_buffer *stats_buffer_list_first(void)
 {
-	struct modem_stats_buffer *first = NULL;
+	struct modem_stats_buffer *first;
 
-	K_SPINLOCK(&stats_buffer_lock) {
-		first = stats_buffer_from_node(sys_slist_peek_head(&stats_buffer_list));
-	}
+	k_spinlock_key_t key = k_spin_lock(&stats_buffer_lock);
+	first = stats_buffer_from_node(sys_slist_peek_head(&stats_buffer_list));
+	k_spin_unlock(&stats_buffer_lock, key);
 
 	return first;
 }
 
 static struct modem_stats_buffer *stats_buffer_list_next(struct modem_stats_buffer *buffer)
 {
-	struct modem_stats_buffer *next = NULL;
+	struct modem_stats_buffer *next;
 
-	K_SPINLOCK(&stats_buffer_lock) {
-		next = stats_buffer_from_node(sys_slist_peek_next(&buffer->node));
-	}
+	k_spinlock_key_t key = k_spin_lock(&stats_buffer_lock);
+	next = stats_buffer_from_node(sys_slist_peek_next(&buffer->node));
+	k_spin_unlock(&stats_buffer_lock, key);
 
 	return next;
 }