[src/trunk]: src/sys/external/bsd/drm2/linux dtrace sdt probes for linux rcu.

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d8375bf9ac72
branches:  trunk
changeset: 366376:d8375bf9ac72
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Aug 27 15:07:59 2018 +0000

description:
dtrace sdt probes for linux rcu.

diffstat:

 sys/external/bsd/drm2/linux/linux_rcu.c |  37 ++++++++++++++++++++++++++++----
 1 files changed, 32 insertions(+), 5 deletions(-)

diffs (95 lines):

diff -r 381220a46b88 -r d8375bf9ac72 sys/external/bsd/drm2/linux/linux_rcu.c
--- a/sys/external/bsd/drm2/linux/linux_rcu.c   Mon Aug 27 15:07:44 2018 +0000
+++ b/sys/external/bsd/drm2/linux/linux_rcu.c   Mon Aug 27 15:07:59 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_rcu.c,v 1.3 2018/08/27 14:14:54 riastradh Exp $  */
+/*     $NetBSD: linux_rcu.c,v 1.4 2018/08/27 15:07:59 riastradh Exp $  */
 
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,16 +30,28 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_rcu.c,v 1.3 2018/08/27 14:14:54 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_rcu.c,v 1.4 2018/08/27 15:07:59 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/condvar.h>
+#include <sys/cpu.h>
 #include <sys/kthread.h>
 #include <sys/mutex.h>
+#include <sys/sdt.h>
 #include <sys/xcall.h>
 
 #include <linux/rcupdate.h>
 
+SDT_PROBE_DEFINE0(sdt, linux, rcu, synchronize__start);
+SDT_PROBE_DEFINE1(sdt, linux, rcu, synchronize__cpu, "unsigned"/*cpu*/);
+SDT_PROBE_DEFINE0(sdt, linux, rcu, synchronize__done);
+SDT_PROBE_DEFINE2(sdt, linux, rcu, call__queue,
+    "struct rcu_head *"/*head*/, "void (*)(struct rcu_head *)"/*callback*/);
+SDT_PROBE_DEFINE2(sdt, linux, rcu, call__run,
+    "struct rcu_head *"/*head*/, "void (*)(struct rcu_head *)"/*callback*/);
+SDT_PROBE_DEFINE2(sdt, linux, rcu, call__done,
+    "struct rcu_head *"/*head*/, "void (*)(struct rcu_head *)"/*callback*/);
+
 static struct {
        kmutex_t        lock;
        kcondvar_t      cv;
@@ -49,15 +61,19 @@
 } gc __cacheline_aligned;
 
 static void
-rcu_xc(void *a, void *b)
+synchronize_rcu_xc(void *a, void *b)
 {
+
+       SDT_PROBE1(sdt, linux, rcu, synchronize__cpu,  cpu_index(curcpu()));
 }
 
 void
 synchronize_rcu(void)
 {
 
-       xc_wait(xc_broadcast(0, &rcu_xc, NULL, NULL));
+       SDT_PROBE0(sdt, linux, rcu, synchronize__start);
+       xc_wait(xc_broadcast(0, &synchronize_rcu_xc, NULL, NULL));
+       SDT_PROBE0(sdt, linux, rcu, synchronize__done);
 }
 
 void
@@ -70,6 +86,7 @@
        head->rcuh_next = gc.first;
        gc.first = head;
        cv_signal(&gc.cv);
+       SDT_PROBE2(sdt, linux, rcu, call__queue,  head, callback);
        mutex_exit(&gc.lock);
 }
 
@@ -77,6 +94,7 @@
 gc_thread(void *cookie)
 {
        struct rcu_head *head, *next;
+       void (*callback)(struct rcu_head *);
 
        mutex_enter(&gc.lock);
        for (;;) {
@@ -95,7 +113,16 @@
                        /* It is now safe to call the callbacks.  */
                        for (; head != NULL; head = next) {
                                next = head->rcuh_next;
-                               (*head->rcuh_callback)(head);
+                               callback = head->rcuh_callback;
+                               SDT_PROBE2(sdt, linux, rcu, call__run,
+                                   head, callback);
+                               (*callback)(head);
+                               /*
+                                * Can't dereference head or invoke
+                                * callback after this point.
+                                */
+                               SDT_PROBE2(sdt, linux, rcu, call__done,
+                                   head, callback);
                        }
 
                        mutex_enter(&gc.lock);