Commit d1a03c29 authored by Wesley Atwell's avatar Wesley Atwell Committed by Steven Rostedt (Google)
Browse files

tracing: Preserve repeated trace_trigger boot parameters 

trace_trigger= tokenizes bootup_trigger_buf in place and stores pointers
into that buffer for later trigger registration. Repeated trace_trigger=
parameters overwrite the buffer contents from earlier calls, leaving
only the last set of parsed event and trigger strings.

Keep each new trace_trigger= string at the end of bootup_trigger_buf and
parse only the appended range. That preserves the earlier event and
trigger strings while still letting repeated parameters queue additional
boot-time triggers.

This also lets Bootconfig array values work naturally when they expand
to repeated trace_trigger= entries.

Before this change, only the last trace_trigger= instance survived boot.

Link: https://patch.msgid.link/20260330181103.1851230-2-atwellwea@gmail.com


Signed-off-by: default avatarWesley Atwell <atwellwea@gmail.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 842b74e5

kernel/trace/trace_events.c

+10 −3
Original line number Diff line number Diff line
@@ -3675,20 +3675,27 @@ static struct boot_triggers { 
} bootup_triggers[MAX_BOOT_TRIGGERS];



static char bootup_trigger_buf[COMMAND_LINE_SIZE];

static int boot_trigger_buf_len;

static int nr_boot_triggers;



static __init int setup_trace_triggers(char *str)

{

	char *trigger;

	char *buf;

	int len = boot_trigger_buf_len;

	int i;



	strscpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);

	if (len >= COMMAND_LINE_SIZE)

		return 1;



	strscpy(bootup_trigger_buf + len, str, COMMAND_LINE_SIZE - len);

	trace_set_ring_buffer_expanded(NULL);

	disable_tracing_selftest("running event triggers");



	buf = bootup_trigger_buf;

	for (i = 0; i < MAX_BOOT_TRIGGERS; i++) {

	buf = bootup_trigger_buf + len;

	boot_trigger_buf_len += strlen(buf) + 1;



	for (i = nr_boot_triggers; i < MAX_BOOT_TRIGGERS; i++) {

		trigger = strsep(&buf, ",");

		if (!trigger)

			break;