linux-kernel - [PATCH RFC 2/8] jump_label: if a key has already been initialized, don't nop it out

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Message-Id: <9305c40efff18a742f1446fa8013af3ed72b01ce.1317338254.git.jeremy.fitzhardinge@citrix.com>
Date:	Thu, 29 Sep 2011 16:26:32 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	David Daney <david.daney@...ium.com>,
	Michael Ellerman <michael@...erman.id.au>,
	Jan Glauber <jang@...ux.vnet.ibm.com>,
	Jason Baron <jbaron@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Xen Devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
Subject: [PATCH RFC 2/8] jump_label: if a key has already been initialized, don't nop it out

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>

If a key has been enabled before jump_label_init() is called, don't
nop it out.

This replaces arch_jump_label_text_poke_early() (which can only nop
out a site) with arch_jump_label_transform_early(), which is functionally
equivalent to arch_jump_label_transform().

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 include/linux/jump_label.h |    3 ++-
 kernel/jump_label.c        |   17 +++++++++++------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 1213e9d..c8fb1b3 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -45,7 +45,8 @@ extern void jump_label_lock(void);
 extern void jump_label_unlock(void);
 extern void arch_jump_label_transform(struct jump_entry *entry,
 				 enum jump_label_type type);
-extern void arch_jump_label_text_poke_early(jump_label_t addr);
+extern void arch_jump_label_transform_early(struct jump_entry *entry,
+				 enum jump_label_type type);
 extern int jump_label_text_reserved(void *start, void *end);
 extern void jump_label_inc(struct jump_label_key *key);
 extern void jump_label_dec(struct jump_label_key *key);
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index a8ce450..54e8e2d 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -124,8 +124,10 @@ static void __jump_label_update(struct jump_label_key *key,
 /*
  * Not all archs need this.
  */
-void __weak arch_jump_label_text_poke_early(jump_label_t addr)
+void __weak arch_jump_label_transform_early(struct jump_entry *entry,
+					    enum jump_label_type type)
 {
+	arch_jump_label_transform(entry, type);	
 }
 
 static __init int jump_label_init(void)
@@ -139,12 +141,15 @@ static __init int jump_label_init(void)
 	jump_label_sort_entries(iter_start, iter_stop);
 
 	for (iter = iter_start; iter < iter_stop; iter++) {
-		arch_jump_label_text_poke_early(iter->code);
-		if (iter->key == (jump_label_t)(unsigned long)key)
+		struct jump_label_key *iterk;
+
+		iterk = (struct jump_label_key *)(unsigned long)iter->key;
+		arch_jump_label_transform_early(iter, jump_label_enabled(iterk) ?
+						JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE);
+		if (iterk == key)
 			continue;
 
-		key = (struct jump_label_key *)(unsigned long)iter->key;
-		atomic_set(&key->enabled, 0);
+		key = iterk;
 		key->entries = iter;
 #ifdef CONFIG_MODULES
 		key->next = NULL;
@@ -212,7 +217,7 @@ void jump_label_apply_nops(struct module *mod)
 		return;
 
 	for (iter = iter_start; iter < iter_stop; iter++)
-		arch_jump_label_text_poke_early(iter->code);
+		arch_jump_label_transform(iter, JUMP_LABEL_DISABLE);
 }
 
 static int jump_label_add_module(struct module *mod)
-- 
1.7.6.2

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