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Subject[PATCH 12/13] jump label v8: convert dynamic debug to use jump labels.
Convert the 'dynamic debug' infrastructure to use jump labels.

Signed-off-by: Jason Baron <jbaron@redhat.com>
---
include/linux/dynamic_debug.h | 42 ++++++++++++++-------------
lib/dynamic_debug.c | 42 ++-------------------------
scripts/Makefile.lib | 11 +------
scripts/basic/Makefile | 2 +-
scripts/basic/hash.c | 64 -----------------------------------------
5 files changed, 27 insertions(+), 134 deletions(-)
delete mode 100644 scripts/basic/hash.c

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index f8c2e17..bb5dfaf 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -1,6 +1,8 @@
#ifndef _DYNAMIC_DEBUG_H
#define _DYNAMIC_DEBUG_H

+#include <linux/jump_label.h>
+
/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
* use independent hash functions, to reduce the chance of false positives.
@@ -22,9 +24,7 @@ struct _ddebug {
const char *function;
const char *filename;
const char *format;
- char primary_hash;
- char secondary_hash;
- unsigned int lineno:24;
+ unsigned int lineno;
/*
* The flags field controls the behaviour at the callsite.
* The bits here are changed dynamically when the user
@@ -32,7 +32,7 @@ struct _ddebug {
*/
#define _DPRINTK_FLAGS_PRINT (1<<0) /* printk() a message using the format */
#define _DPRINTK_FLAGS_DEFAULT 0
- unsigned int flags:8;
+ char flags;
} __attribute__((aligned(8)));


@@ -42,33 +42,35 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
#if defined(CONFIG_DYNAMIC_DEBUG)
extern int ddebug_remove_module(char *mod_name);

-#define __dynamic_dbg_enabled(dd) ({ \
- int __ret = 0; \
- if (unlikely((dynamic_debug_enabled & (1LL << DEBUG_HASH)) && \
- (dynamic_debug_enabled2 & (1LL << DEBUG_HASH2)))) \
- if (unlikely(dd.flags)) \
- __ret = 1; \
- __ret; })
-
#define dynamic_pr_debug(fmt, ...) do { \
+ __label__ do_printk; \
+ __label__ out; \
static struct _ddebug descriptor \
__used \
__attribute__((section("__verbose"), aligned(8))) = \
- { KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH, \
- DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT }; \
- if (__dynamic_dbg_enabled(descriptor)) \
- printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
+ { KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__, \
+ _DPRINTK_FLAGS_DEFAULT }; \
+ JUMP_LABEL(&descriptor.flags, do_printk); \
+ goto out; \
+do_printk: \
+ printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
+out: ; \
} while (0)


#define dynamic_dev_dbg(dev, fmt, ...) do { \
+ __label__ do_printk; \
+ __label__ out; \
static struct _ddebug descriptor \
__used \
__attribute__((section("__verbose"), aligned(8))) = \
- { KBUILD_MODNAME, __func__, __FILE__, fmt, DEBUG_HASH, \
- DEBUG_HASH2, __LINE__, _DPRINTK_FLAGS_DEFAULT }; \
- if (__dynamic_dbg_enabled(descriptor)) \
- dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); \
+ { KBUILD_MODNAME, __func__, __FILE__, fmt, __LINE__, \
+ _DPRINTK_FLAGS_DEFAULT }; \
+ JUMP_LABEL(&descriptor.flags, do_printk); \
+ goto out; \
+do_printk: \
+ dev_printk(KERN_DEBUG, dev, fmt, ##__VA_ARGS__); \
+out: ; \
} while (0)

#else
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index d6b8b9b..ed0193a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -26,19 +26,11 @@
#include <linux/dynamic_debug.h>
#include <linux/debugfs.h>
#include <linux/slab.h>
+#include <linux/jump_label.h>

extern struct _ddebug __start___verbose[];
extern struct _ddebug __stop___verbose[];

-/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which
- * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
- * use independent hash functions, to reduce the chance of false positives.
- */
-long long dynamic_debug_enabled;
-EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
-long long dynamic_debug_enabled2;
-EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);
-
struct ddebug_table {
struct list_head link;
char *mod_name;
@@ -88,26 +80,6 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
}

/*
- * must be called with ddebug_lock held
- */
-
-static int disabled_hash(char hash, bool first_table)
-{
- struct ddebug_table *dt;
- char table_hash_value;
-
- list_for_each_entry(dt, &ddebug_tables, link) {
- if (first_table)
- table_hash_value = dt->ddebugs->primary_hash;
- else
- table_hash_value = dt->ddebugs->secondary_hash;
- if (dt->num_enabled && (hash == table_hash_value))
- return 0;
- }
- return 1;
-}
-
-/*
* Search the tables for _ddebug's which match the given
* `query' and apply the `flags' and `mask' to them. Tells
* the user which ddebug's were changed, or whether none
@@ -170,17 +142,9 @@ static void ddebug_change(const struct ddebug_query *query,
dt->num_enabled++;
dp->flags = newflags;
if (newflags) {
- dynamic_debug_enabled |=
- (1LL << dp->primary_hash);
- dynamic_debug_enabled2 |=
- (1LL << dp->secondary_hash);
+ enable_jump_label((jump_label_t)&dp->flags);
} else {
- if (disabled_hash(dp->primary_hash, true))
- dynamic_debug_enabled &=
- ~(1LL << dp->primary_hash);
- if (disabled_hash(dp->secondary_hash, false))
- dynamic_debug_enabled2 &=
- ~(1LL << dp->secondary_hash);
+ disable_jump_label((jump_label_t)&dp->flags);
}
if (verbose)
printk(KERN_INFO
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index cbcd654..6a162fc 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -101,14 +101,6 @@ basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
modname_flags = $(if $(filter 1,$(words $(modname))),\
-D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")

-#hash values
-ifdef CONFIG_DYNAMIC_DEBUG
-debug_flags = -D"DEBUG_HASH=$(shell ./scripts/basic/hash djb2 $(@D)$(modname))"\
- -D"DEBUG_HASH2=$(shell ./scripts/basic/hash r5 $(@D)$(modname))"
-else
-debug_flags =
-endif
-
orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \
$(ccflags-y) $(CFLAGS_$(basetarget).o)
_c_flags = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(orig_c_flags))
@@ -152,8 +144,7 @@ endif

c_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(__c_flags) $(modkern_cflags) \
- -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags) \
- $(debug_flags)
+ -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)

a_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \
$(__a_flags) $(modkern_aflags)
diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile
index 0955995..4c324a1 100644
--- a/scripts/basic/Makefile
+++ b/scripts/basic/Makefile
@@ -9,7 +9,7 @@
# fixdep: Used to generate dependency information during build process
# docproc: Used in Documentation/DocBook

-hostprogs-y := fixdep docproc hash
+hostprogs-y := fixdep docproc
always := $(hostprogs-y)

# fixdep is needed to compile other host programs
diff --git a/scripts/basic/hash.c b/scripts/basic/hash.c
deleted file mode 100644
index 2ef5d3f..0000000
--- a/scripts/basic/hash.c
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
- * Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
- *
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-#define DYNAMIC_DEBUG_HASH_BITS 6
-
-static const char *program;
-
-static void usage(void)
-{
- printf("Usage: %s <djb2|r5> <modname>\n", program);
- exit(1);
-}
-
-/* djb2 hashing algorithm by Dan Bernstein. From:
- * http://www.cse.yorku.ca/~oz/hash.html
- */
-
-static unsigned int djb2_hash(char *str)
-{
- unsigned long hash = 5381;
- int c;
-
- c = *str;
- while (c) {
- hash = ((hash << 5) + hash) + c;
- c = *++str;
- }
- return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
-}
-
-static unsigned int r5_hash(char *str)
-{
- unsigned long hash = 0;
- int c;
-
- c = *str;
- while (c) {
- hash = (hash + (c << 4) + (c >> 4)) * 11;
- c = *++str;
- }
- return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
-}
-
-int main(int argc, char *argv[])
-{
- program = argv[0];
-
- if (argc != 3)
- usage();
- if (!strcmp(argv[1], "djb2"))
- printf("%d\n", djb2_hash(argv[2]));
- else if (!strcmp(argv[1], "r5"))
- printf("%d\n", r5_hash(argv[2]));
- else
- usage();
- exit(0);
-}
-
--
1.7.0.1


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