Enable use of DTRACE_PROBE* macros in "spl" module

This change modifies some of the infrastructure for enabling the use of
the DTRACE_PROBE* macros, such that we can use tehm in the "spl" module.

Currently, when the DTRACE_PROBE* macros are used, they get expanded to
create new functions, and these dynamically generated functions become
part of the "zfs" module.

Since the "spl" module does not depend on the "zfs" module, the use of
DTRACE_PROBE* in the "spl" module would result in undefined symbols
being used in the "spl" module. Specifically, DTRACE_PROBE* would turn
into a function call, and the function being called would be a symbol
only contained in the "zfs" module; which results in a linker and/or
runtime error.

Thus, this change adds the necessary logic to the "spl" module, to
mirror the tracing functionality available to the "zfs" module. After
this change, we'll have a "trace_zfs.h" header file which defines the
probes available only to the "zfs" module, and a "trace_spl.h" header
file which defines the probes available only to the "spl" module.

Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Closes #9525

module/os/linux/spl/Makefile.in

@@ -11,6 +11,7 @@ $(MODULE)-objs += ../os/linux/spl/spl-proc.o
 $(MODULE)-objs += ../os/linux/spl/spl-procfs-list.o
 $(MODULE)-objs += ../os/linux/spl/spl-taskq.o
 $(MODULE)-objs += ../os/linux/spl/spl-thread.o
+$(MODULE)-objs += ../os/linux/spl/spl-trace.o
 $(MODULE)-objs += ../os/linux/spl/spl-tsd.o
 $(MODULE)-objs += ../os/linux/spl/spl-vmem.o
 $(MODULE)-objs += ../os/linux/spl/spl-vnode.o

module/os/linux/spl/spl-trace.c

@@ -0,0 +1,30 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Each DTRACE_PROBE must define its trace point in one (and only one)
+ * source file, so this dummy file exists for that purpose.
+ */
+
+#ifdef _KERNEL
+#define	CREATE_TRACE_POINTS
+#include <sys/trace.h>
+#endif

module/os/linux/zfs/arc_os.c

@@ -54,7 +54,7 @@
 #include <sys/zthr.h>
 #include <zfs_fletcher.h>
 #include <sys/arc_impl.h>
-#include <sys/trace_defs.h>
+#include <sys/trace_zfs.h>
 #include <sys/aggsum.h>
 
 int64_t last_free_memory;

module/os/linux/zfs/trace.c

@@ -41,6 +41,7 @@
 #include <sys/trace.h>
 #include <sys/trace_acl.h>
 #include <sys/trace_arc.h>
+#include <sys/trace_dbgmsg.h>
 #include <sys/trace_dbuf.h>
 #include <sys/trace_dmu.h>
 #include <sys/trace_dnode.h>

module/os/linux/zfs/zfs_debug.c

@@ -24,6 +24,7 @@
  */
 
 #include <sys/zfs_context.h>
+#include <sys/trace_zfs.h>
 
 typedef struct zfs_dbgmsg {
 	procfs_list_node_t	zdm_node;

module/os/linux/zfs/zio_os.c

@@ -29,7 +29,7 @@
 #include <sys/zio.h>
 #include <sys/zio_impl.h>
 #include <sys/time.h>
-#include <sys/trace_defs.h>
+#include <sys/trace_zfs.h>
 
 void
 zio_delay_interrupt(zio_t *zio)