[PATCH 0/2] tracing: make signal tracepoints more useful

[Oleg Nesterov <oleg@redhat.com>]

Hello.

Linus, I am asking you to review (and hopefully apply) these
changes, I do not know who else can do this. I do not mean the
implementation, the patches are simple. Just the behavioural
change.

2/2 looks like a bugfix to me, but 1/2 changes the output from
trace_signal_generate() and removes trace_signal_overflow_fail.
In essence the change is:

	-       TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d",
	+       TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d",

where
	- grp=0/1 means private or shared

	- res is enum {
			TRACE_SIGNAL_DELIVERED,
			TRACE_SIGNAL_IGNORED,
			TRACE_SIGNAL_ALREADY_PENDING,
			TRACE_SIGNAL_OVERFLOW_FAIL,
			TRACE_SIGNAL_LOSE_INFO,
		};

Obviously this is the user visible change. But personally I do
agree with Seiji who requested this feature. Currently
trace_signal_generate() just records the fact that __send_signal()
was called, you can't know whether the signal was actually sent
or not.

 include/trace/events/signal.h |   85 +++++++++++------------------------------
 kernel/signal.c               |   28 +++++++++----
 2 files changed, 41 insertions(+), 72 deletions(-)