tracepoint: Add signal loss events

Add signal_overflow_fail and signal_lose_info tracepoints
for signal-lost events.

Changes in v3:
 - Add docbook style comments

Changes in v2:
 - Use siginfo string macro

Suggested-by: Roland McGrath <roland@redhat.com>
Reviewed-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Oleg Nesterov <oleg@redhat.com>
LKML-Reference: <20091124215658.30449.9934.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 14 insertions, 5 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 349d44937406..93e72e5feae6 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -897,12 +897,21 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
                         break;
                 }
         } else if (!is_si_special(info)) {
-                if (sig >= SIGRTMIN && info->si_code != SI_USER)
-                /*
-                 * Queue overflow, abort.  We may abort if the signal was rt
-                 * and sent by user using something other than kill().
-                 */
+                if (sig >= SIGRTMIN && info->si_code != SI_USER) {
+                        /*
+                         * Queue overflow, abort.  We may abort if the
+                         * signal was rt and sent by user using something
+                         * other than kill().
+                         */
+                        trace_signal_overflow_fail(sig, group, info);
                         return -EAGAIN;
+                } 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);
+                }
         }
 
 out_set: