Merge branch 'github/fork/emersion/tracing' into 'master'

Add kernel tracing instrumentation

See merge request wlroots/wlroots!2791

util/meson.build

@@ -13,6 +13,7 @@ wlr_files += files(
 	'shm.c',
 	'time.c',
 	'token.c',
+	'trace.c',
 	'transform.c',
 	'utf8.c',
 	'version.c',

util/trace.c

@@ -0,0 +1,58 @@
+#include <inttypes.h>
+#include <stdio.h>
+#include "util/trace.h"
+
+static bool trace_initialized = false;
+static FILE *trace_file = NULL;
+static uint32_t prev_ctx = 0;
+
+void wlr_vtrace(const char *fmt, va_list args) {
+	if (!trace_initialized) {
+		trace_initialized = true;
+		trace_file = fopen("/sys/kernel/tracing/trace_marker", "w");
+		if (trace_file != NULL) {
+			wlr_log(WLR_INFO, "Kernel tracing is enabled");
+		}
+	}
+
+	if (trace_file == NULL) {
+		return;
+	}
+
+	vfprintf(trace_file, fmt, args);
+	fprintf(trace_file, "\n");
+	fflush(trace_file);
+}
+
+void wlr_trace(const char *fmt, ...) {
+	va_list args;
+	va_start(args, fmt);
+	wlr_vtrace(fmt, args);
+	va_end(args);
+}
+
+void wlr_trace_begin_ctx(struct wlr_trace_ctx *ctx, const char *fmt, ...) {
+	*ctx = (struct wlr_trace_ctx){
+		.seq = prev_ctx++,
+	};
+
+	static char new_fmt[512];
+	snprintf(new_fmt, sizeof(new_fmt), "%s (begin_ctx=%"PRIu32")", fmt, ctx->seq);
+
+	va_list args;
+	va_start(args, fmt);
+	wlr_vtrace(new_fmt, args);
+	va_end(args);
+}
+
+void wlr_trace_end_ctx(struct wlr_trace_ctx *ctx, const char *fmt, ...) {
+	static char new_fmt[512];
+	snprintf(new_fmt, sizeof(new_fmt), "%s (end_ctx=%"PRIu32")", fmt, ctx->seq);
+
+	va_list args;
+	va_start(args, fmt);
+	wlr_vtrace(new_fmt, args);
+	va_end(args);
+
+	ctx->seq = 0;
+}