logging: rpc: filter out rpc logs for streaming only

The Logging over RPC backend would filter out logs generated
by nRF RPC to avoid the log infinite loop. However, this is
only necessary for log live-streaming but it is perfectly ok
to include nRF RPC logs in the log history buffer.

Signed-off-by: Damian Krolik <[email protected]>

Author: Damian-Nordic

subsys/logging/log_backend_rpc.c

@@ -92,19 +92,6 @@ static struct coredump_mem_region_node dump_region = {
 static const uint8_t CRASH_INFO_MAGIC[] = { 'D', 'U', 'M', 'P', 'I', 'N', 'F', 'O' };
 #endif
 
-/*
- * Drop messages coming from nRF RPC to avoid the avalanche of logs:
- * 1. log added
- * 2. log sent over nRF RPC
- * 3. more logs generated by nRF RPC
- * 4. more logs sent over nRF RPC
- * ...
- */
-static const char *const filtered_out_sources[] = {
-	"nrf_rpc",
-	"NRF_RPC",
-};
-
 static const uint32_t common_output_flags =
 	LOG_OUTPUT_FLAG_TIMESTAMP | LOG_OUTPUT_FLAG_FORMAT_TIMESTAMP;
 
@@ -539,28 +526,47 @@ static bool starts_with(const char *str, const char *prefix)
 	return strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
-static void process(const struct log_backend *const backend, union log_msg_generic *msg_generic)
+static bool should_filter_out(struct log_msg *msg)
 {
-	struct log_msg *msg = &msg_generic->log;
+	/*
+	 * Drop messages coming from nRF RPC to avoid the log feedback loop:
+	 * 1. log added
+	 * 2. log sent over nRF RPC
+	 * 3. more logs generated by nRF RPC
+	 * 4. more logs sent over nRF RPC
+	 * ...
+	 */
+	static const char *const filtered_out_sources[] = {
+		"nrf_rpc",
+		"NRF_RPC",
+	};
+
 	const char *source_name = log_msg_source_name_get(msg);
-	enum log_rpc_level level = (enum log_rpc_level)log_msg_get_level(msg);
-	enum log_rpc_level max_level;
 
 	if (source_name != NULL) {
 		for (size_t i = 0; i < ARRAY_SIZE(filtered_out_sources); i++) {
 			if (starts_with(source_name, filtered_out_sources[i])) {
-				return;
+				return true;
 			}
 		}
 	}
 
+	return false;
+}
+
+static void process(const struct log_backend *const backend, union log_msg_generic *msg_generic)
+{
+	struct log_msg *msg = &msg_generic->log;
+	enum log_rpc_level level = (enum log_rpc_level)log_msg_get_level(msg);
+	enum log_rpc_level max_level;
+
 	if (panic_mode) {
 		return;
 	}
 
 	max_level = stream_level;
 
-	if (max_level != LOG_RPC_LEVEL_NONE && level <= max_level) {
+	if (max_level != LOG_RPC_LEVEL_NONE && level <= max_level && !should_filter_out(msg)) {
 		/*
 		 * The "max_level != LOG_RPC_LEVEL_NONE" condition seems redundant but is in fact
 		 * needed, because a log message can be generated with the level NONE, and such