linux-kernel - Re: [PATCH] mm/init: cpu_hotplug_init() must be initialized before SLAB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LFD.2.01.0906221927280.3240@localhost.localdomain>
Date:	Mon, 22 Jun 2009 19:29:18 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
cc:	James Bottomley <James.Bottomley@...senPartnership.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Sachin Sant <sachinp@...ibm.com>
Subject: Re: [PATCH] mm/init: cpu_hotplug_init() must be initialized before
 SLAB



On Tue, 23 Jun 2009, Benjamin Herrenschmidt wrote:

> +	/*
> +	 * This initializes the mutex used by get/put_online_cpus()
> +	 * which is used by SLAB
> +	 */
> +	cpu_hotplug_init();

Oh fudge it.

Why not get rid of that stupid thing, rather than have that subtle 
dependency and a comment for it.

IOW, does this simpler alternative also work?

When given the choice of simplifying and removing code, always do so. 

Static initializers are much nicer than having to worry about when 
something gets initialized, no?

		Linus

---
 include/linux/cpu.h |    5 -----
 init/main.c         |    1 -
 kernel/cpu.c        |   13 +++++--------
 3 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 2643d84..4d668e0 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -69,7 +69,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
 
 int cpu_up(unsigned int cpu);
 void notify_cpu_starting(unsigned int cpu);
-extern void cpu_hotplug_init(void);
 extern void cpu_maps_update_begin(void);
 extern void cpu_maps_update_done(void);
 
@@ -84,10 +83,6 @@ static inline void unregister_cpu_notifier(struct notifier_block *nb)
 {
 }
 
-static inline void cpu_hotplug_init(void)
-{
-}
-
 static inline void cpu_maps_update_begin(void)
 {
 }
diff --git a/init/main.c b/init/main.c
index 09131ec..4870dfe 100644
--- a/init/main.c
+++ b/init/main.c
@@ -678,7 +678,6 @@ asmlinkage void __init start_kernel(void)
 #endif
 	page_cgroup_init();
 	enable_debug_pagealloc();
-	cpu_hotplug_init();
 	kmemtrace_init();
 	kmemleak_init();
 	debug_objects_mem_init();
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 395b697..8ce1004 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -34,14 +34,11 @@ static struct {
 	 * an ongoing cpu hotplug operation.
 	 */
 	int refcount;
-} cpu_hotplug;
-
-void __init cpu_hotplug_init(void)
-{
-	cpu_hotplug.active_writer = NULL;
-	mutex_init(&cpu_hotplug.lock);
-	cpu_hotplug.refcount = 0;
-}
+} cpu_hotplug = {
+	.active_writer = NULL,
+	.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
+	.refcount = 0,
+};
 
 #ifdef CONFIG_HOTPLUG_CPU
 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/