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tracing: Disable trace_printk buffer on warning too

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When /proc/sys/kernel/traceoff_on_warning is set to 1, the top level
tracing buffer is disabled when a warning happens. This is very useful
when debugging and want the tracing buffer to stop taking new data when a
warning triggers keeping the events that lead up to the warning from being
overwritten.

Now that there is also a persistent ring buffer and an option to have
trace_printk go to that buffer, the same holds true for that buffer. A
warning could happen just before a crash but still write enough events to
lose the events that lead up to the first warning that was the reason for
the crash.

When /proc/sys/kernel/traceoff_on_warning is set to 1 and a warning is
triggered, not only disable the top level tracing buffer, but also disable
the buffer that trace_printk()s are written to.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://patch.msgid.link/20260121093858.5c5d7e7b@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2026-01-21 09:38:58 -05:00
committed by Steven Rostedt (Google)
parent a9e0c5897a
commit 6bdf07302f
1 changed files with 9 additions and 0 deletions
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9
kernel/trace/trace.c
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@@ -1666,9 +1666,18 @@ EXPORT_SYMBOL_GPL(tracing_off);
void disable_trace_on_warning(void)
{
if (__disable_trace_on_warning) {
struct trace_array *tr = READ_ONCE(printk_trace);
trace_array_printk_buf(global_trace.array_buffer.buffer, _THIS_IP_,
"Disabling tracing due to warning\n");
tracing_off();
/* Disable trace_printk() buffer too */
if (tr != &global_trace) {
trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_,
"Disabling tracing due to warning\n");
tracer_tracing_off(tr);
}
}
}