(Was: Q: tracing: can we change trace_signal_generate() signature?)

Quoted 4 lines · Oleg Nesterov

Heh. How can I do this? The only thing I can do is: send the patch to the maintainer - you ;)

OK. I'll send the patch "officially" tomorrow, let's see who nacks it.

I only maintain the tracing infrastructure. The tracepoint users are maintained by the subsystem they are used in. Who's the signal maintainer? ;)

Quoted 20 lines

Quoted 19 lines

Quoted 6 lines

(quoted diff) +0 -2

@@ -1095,14 +1106,15 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 			 * signal was rt and sent by user using something
 			 * other than kill().
 			 */
-			trace_signal_overflow_fail(sig, group, info);
-			return -EAGAIN;

Review static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, · line 1117

Quoted 10 lines

(quoted diff) +4 -1

+			result = TRACE_SIGNAL_OVERFLOW_FAIL;
+			ret = -EAGAIN;
+			goto ret;
 		} else {
 			/*
 			 * This is a silent loss of information.  We still
 			 * send the signal, but the *info bits are lost.
 			 */
-			trace_signal_lose_info(sig, group, info);
+			result = TRACE_SIGNAL_LOSE_INFO;

Hmm, all this result manipulation added for tracing that doesn't occur in 99.99% of all machines?

Quoted 1 line

Not sure I understand...

Is "result" used for anything but tracepoints? When tracing is disabled, the tracepoints should be just nops (when jump_label is enabled). Thus tracing is very light. But if we are constantly calculating "result", this is unused by those that don't use the tracing infrastructure, which is 99.99% of all users. This is what I meant.