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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: Wesley Atwell <atwellwea@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
master
Wesley Atwell 2026-03-30 12:11:03 -06:00 committed by Steven Rostedt (Google)
parent 842b74e5ce
commit d1a03c2906
1 changed files with 10 additions and 3 deletions
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13
kernel/trace/trace_events.c
View File

@ -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;