Subject: perf, core: Introduce perf_initcall()
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu Nov 25 15:27:49 CET 2010

In order to initialize the built-in hardware PMU drivers before
early_initcall() -- which is used by the watchdog code and expects the
hardware PMUs to be present.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
---
 include/asm-generic/vmlinux.lds.h |    2 +
 include/linux/init.h              |    7 +++++
 init/main.c                       |   53 ++++++++++++++++++++++----------------
 3 files changed, 40 insertions(+), 22 deletions(-)

Index: linux-2.6/include/asm-generic/vmlinux.lds.h
===================================================================
--- linux-2.6.orig/include/asm-generic/vmlinux.lds.h
+++ linux-2.6/include/asm-generic/vmlinux.lds.h
@@ -600,6 +600,8 @@
 		VMLINUX_SYMBOL(__setup_end) = .;
 
 #define INITCALLS							\
+	*(.initcallperf.init)						\
+	VMLINUX_SYMBOL(__perf_initcall_end) = .;			\
 	*(.initcallearly.init)						\
 	VMLINUX_SYMBOL(__early_initcall_end) = .;			\
   	*(.initcall0.init)						\
Index: linux-2.6/include/linux/init.h
===================================================================
--- linux-2.6.orig/include/linux/init.h
+++ linux-2.6/include/linux/init.h
@@ -179,6 +179,13 @@ extern int initcall_debug;
 	__attribute__((__section__(".initcall" level ".init"))) = fn
 
 /*
+ * Very early initcalls, run after the perf core is up.
+ *
+ * Only for build-in code, not modules.
+ */
+#define perf_initcall(fn)		__define_initcall("perf",fn,perf)
+
+/*
  * Early initcalls run before initializing SMP.
  *
  * Only for built-in code, not modules.
Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -515,6 +515,36 @@ void __init __weak thread_info_cache_ini
 {
 }
 
+extern initcall_t __initcall_start[], __initcall_end[],
+		  __perf_initcall_end[], __early_initcall_end[];
+
+static void __init do_perf_initcalls(void)
+{
+	initcall_t *fn;
+
+	for (fn = __initcall_start; fn < __perf_initcall_end; fn++)
+		do_one_initcall(*fn);
+}
+
+static void __init do_pre_smp_initcalls(void)
+{
+	initcall_t *fn;
+
+	for (fn = __perf_initcall_end; fn < __early_initcall_end; fn++)
+		do_one_initcall(*fn);
+}
+
+static void __init do_initcalls(void)
+{
+	initcall_t *fn;
+
+	for (fn = __early_initcall_end; fn < __initcall_end; fn++)
+		do_one_initcall(*fn);
+
+	/* Make sure there is no pending stuff from the initcall sequence */
+	flush_scheduled_work();
+}
+
 /*
  * Set up kernel memory allocators
  */
@@ -605,6 +635,7 @@ asmlinkage void __init start_kernel(void
 		local_irq_disable();
 	}
 	perf_event_init();
+	do_perf_initcalls();
 	rcu_init();
 	radix_tree_init();
 	/* init some links before init_ISA_irqs() */
@@ -768,20 +799,6 @@ int __init_or_module do_one_initcall(ini
 	return ret;
 }
 
-
-extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
-
-static void __init do_initcalls(void)
-{
-	initcall_t *fn;
-
-	for (fn = __early_initcall_end; fn < __initcall_end; fn++)
-		do_one_initcall(*fn);
-
-	/* Make sure there is no pending stuff from the initcall sequence */
-	flush_scheduled_work();
-}
-
 /*
  * Ok, the machine is now initialized. None of the devices
  * have been touched yet, but the CPU subsystem is up and
@@ -800,14 +817,6 @@ static void __init do_basic_setup(void)
 	do_initcalls();
 }
 
-static void __init do_pre_smp_initcalls(void)
-{
-	initcall_t *fn;
-
-	for (fn = __initcall_start; fn < __early_initcall_end; fn++)
-		do_one_initcall(*fn);
-}
-
 static void run_init_process(const char *init_filename)
 {
 	argv_init[0] = init_filename;