From: Jason Baron <jbaron@redhat.com>
Date: Tue, 1 Dec 2009 21:59:56 -0500
Subject: [trace] add itimer tracepoints
Message-id: <20091201215955.GA6458@redhat.com>
Patchwork-id: 21625
O-Subject: [RHEL5.5 PATCH] tracepoint: add itimer tracepoints
Bugzilla: 534178
RH-Acked-by: Larry Woodman <lwoodman@redhat.com>

hi,

Add two itimer tracepoints to 5.5. The first one, 'itimer_state',
precisely copies the upstream tracepoint. The second one,
'itimer_expire', differs from upstream in that the second of the 3
parameters is a 'struct signal_struct', whereas upstream passes a
'struct pid'. The corresponding 'struct pid' can still be derived from
the 'struct signal_struct'. RHEL5.5 would need extra memory references
in order to get to the correct 'struct pid', and since the compiler
evaluates the arguments, even when the tracepoint is disabled, I think
this is reasonable. BZ #534178.

thanks,

-Jason

Signed-off-by: Don Zickus <dzickus@redhat.com>

diff --git a/include/trace/timer.h b/include/trace/timer.h
new file mode 100644
index 0000000..d1699d6
--- /dev/null
+++ b/include/trace/timer.h
@@ -0,0 +1,15 @@
+#ifndef _TRACE_TIMER_H
+#define _TRACE_TIMER_H
+
+#include <linux/tracepoint.h>
+
+DEFINE_TRACE(itimer_state,
+	TPPROTO(int which, struct itimerval *value,
+		cputime_t expires),
+	TPARGS(which, value, expires));
+DEFINE_TRACE(itimer_expire,
+	TPPROTO(int which, struct signal_struct *sig, cputime_t now),
+	TPARGS(which, sig, now));
+
+
+#endif
diff --git a/kernel/itimer.c b/kernel/itimer.c
index 204ed79..46ede01 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -13,6 +13,7 @@
 #include <linux/time.h>
 #include <linux/posix-timers.h>
 #include <linux/hrtimer.h>
+#include <trace/timer.h>
 
 #include <asm/uaccess.h>
 
@@ -133,6 +134,7 @@ int it_real_fn(struct hrtimer *timer)
 	struct signal_struct *sig =
 	    container_of(timer, struct signal_struct, real_timer);
 
+	trace_itimer_expire(ITIMER_REAL, sig, 0);
 	send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);
 
 	if (sig->it_real_incr.tv64 != 0) {
@@ -236,6 +238,7 @@ again:
 		expires = timeval_to_ktime(value->it_value);
 		if (expires.tv64 != 0)
 			hrtimer_start(timer, expires, HRTIMER_REL);
+		trace_itimer_state(ITIMER_REAL, value, 0);
 		spin_unlock_irq(&tsk->sighand->siglock);
 		break;
 	case ITIMER_VIRTUAL:
@@ -255,6 +258,7 @@ again:
 		}
 		tsk->signal->it_virt_expires = nval;
 		tsk->signal->it_virt_incr = ninterval;
+		trace_itimer_state(ITIMER_VIRTUAL, value, nval);
 		spin_unlock_irq(&tsk->sighand->siglock);
 		read_unlock(&tasklist_lock);
 		if (ovalue) {
@@ -279,6 +283,7 @@ again:
 		}
 		tsk->signal->it_prof_expires = nval;
 		tsk->signal->it_prof_incr = ninterval;
+		trace_itimer_state(ITIMER_PROF, value, nval);
 		spin_unlock_irq(&tsk->sighand->siglock);
 		read_unlock(&tasklist_lock);
 		if (ovalue) {