LKML: Ming Lei: Re: [PATCH 1/3] kref: Inline all functions

Hi,

On Sat, Dec 10, 2011 at 6:43 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> These are tiny functions, there's no point in having them out-of-line.

Looks like no much text size increase in built vmlinux for ARM.

[tom@linux-2.6-omap]$size vmlinux
text data bss dec hex filename
6030247 2083292 7912356 16025895 f48927 vmlinux

[tom@linux-2.6-omap]$size vmlinux-before-kref-inline
text data bss dec hex filename
6023264 2083300 7912356 16018920 f46de8 vmlinux-before-kref-inline

>
> Cc: adobriyan@gmail.com
> Cc: eric.dumazet@gmail.com
> Cc: mingo@elte.hu
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
> include/linux/kref.h | 79 ++++++++++++++++++++++++++++++++++++++---
> lib/Makefile | 2 -
> lib/kref.c | 97 ---------------------------------------------------
> 3 files changed, 75 insertions(+), 103 deletions(-)
>
> Index: linux-2.6/include/linux/kref.h
> ===================================================================
> --- linux-2.6.orig/include/linux/kref.h
> +++ linux-2.6/include/linux/kref.h
> @@ -21,10 +21,79 @@ struct kref {
> atomic_t refcount;
> };
>
> -void kref_init(struct kref *kref);
> -void kref_get(struct kref *kref);
> -int kref_put(struct kref *kref, void (*release) (struct kref *kref));
> -int kref_sub(struct kref *kref, unsigned int count,
> - void (*release) (struct kref *kref));
> +/**
> + * kref_init - initialize object.
> + * @kref: object in question.
> + */
> +static inline void kref_init(struct kref *kref)
> +{
> + atomic_set(&kref->refcount, 1);
> + smp_mb();
> +}
>
> +/**
> + * kref_get - increment refcount for object.
> + * @kref: object.
> + */
> +static inline void kref_get(struct kref *kref)
> +{
> + WARN_ON(!atomic_read(&kref->refcount));
> + atomic_inc(&kref->refcount);
> + smp_mb__after_atomic_inc();
> +}
> +
> +/**
> + * kref_put - decrement refcount for object.
> + * @kref: object.
> + * @release: pointer to the function that will clean up the object when the
> + * last reference to the object is released.
> + * This pointer is required, and it is not acceptable to pass kfree
> + * in as this function.
> + *
> + * Decrement the refcount, and if 0, call release().
> + * Return 1 if the object was removed, otherwise return 0. Beware, if this
> + * function returns 0, you still can not count on the kref from remaining in
> + * memory. Only use the return value if you want to see if the kref is now
> + * gone, not present.
> + */
> +static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
> +{
> + WARN_ON(release == NULL);
> + WARN_ON(release == (void (*)(struct kref *))kfree);

<linux/slab.h> is needed to avoid compiling failure.

> +
> + if (atomic_dec_and_test(&kref->refcount)) {
> + release(kref);
> + return 1;
> + }
> + return 0;
> +}
> +
> +
> +/**
> + * kref_sub - subtract a number of refcounts for object.
> + * @kref: object.
> + * @count: Number of recounts to subtract.
> + * @release: pointer to the function that will clean up the object when the
> + * last reference to the object is released.
> + * This pointer is required, and it is not acceptable to pass kfree
> + * in as this function.
> + *
> + * Subtract @count from the refcount, and if 0, call release().
> + * Return 1 if the object was removed, otherwise return 0. Beware, if this
> + * function returns 0, you still can not count on the kref from remaining in
> + * memory. Only use the return value if you want to see if the kref is now
> + * gone, not present.
> + */
> +static inline int kref_sub(struct kref *kref, unsigned int count,
> + void (*release)(struct kref *kref))
> +{
> + WARN_ON(release == NULL);
> + WARN_ON(release == (void (*)(struct kref *))kfree);
> +
> + if (atomic_sub_and_test((int) count, &kref->refcount)) {
> + release(kref);
> + return 1;
> + }
> + return 0;
> +}
> #endif /* _KREF_H_ */
> Index: linux-2.6/lib/kref.c
> ===================================================================
> --- linux-2.6.orig/lib/kref.c
> +++ /dev/null
> @@ -1,97 +0,0 @@
> -/*
> - * kref.c - library routines for handling generic reference counted objects
> - *
> - * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
> - * Copyright (C) 2004 IBM Corp.
> - *
> - * based on lib/kobject.c which was:
> - * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org>
> - *
> - * This file is released under the GPLv2.
> - *
> - */
> -
> -#include <linux/kref.h>
> -#include <linux/module.h>
> -#include <linux/slab.h>
> -
> -/**
> - * kref_init - initialize object.
> - * @kref: object in question.
> - */
> -void kref_init(struct kref *kref)
> -{
> - atomic_set(&kref->refcount, 1);
> - smp_mb();
> -}
> -
> -/**
> - * kref_get - increment refcount for object.
> - * @kref: object.
> - */
> -void kref_get(struct kref *kref)
> -{
> - WARN_ON(!atomic_read(&kref->refcount));
> - atomic_inc(&kref->refcount);
> - smp_mb__after_atomic_inc();
> -}
> -
> -/**
> - * kref_put - decrement refcount for object.
> - * @kref: object.
> - * @release: pointer to the function that will clean up the object when the
> - * last reference to the object is released.
> - * This pointer is required, and it is not acceptable to pass kfree
> - * in as this function.
> - *
> - * Decrement the refcount, and if 0, call release().
> - * Return 1 if the object was removed, otherwise return 0. Beware, if this
> - * function returns 0, you still can not count on the kref from remaining in
> - * memory. Only use the return value if you want to see if the kref is now
> - * gone, not present.
> - */
> -int kref_put(struct kref *kref, void (*release)(struct kref *kref))
> -{
> - WARN_ON(release == NULL);
> - WARN_ON(release == (void (*)(struct kref *))kfree);
> -
> - if (atomic_dec_and_test(&kref->refcount)) {
> - release(kref);
> - return 1;
> - }
> - return 0;
> -}
> -
> -
> -/**
> - * kref_sub - subtract a number of refcounts for object.
> - * @kref: object.
> - * @count: Number of recounts to subtract.
> - * @release: pointer to the function that will clean up the object when the
> - * last reference to the object is released.
> - * This pointer is required, and it is not acceptable to pass kfree
> - * in as this function.
> - *
> - * Subtract @count from the refcount, and if 0, call release().
> - * Return 1 if the object was removed, otherwise return 0. Beware, if this
> - * function returns 0, you still can not count on the kref from remaining in
> - * memory. Only use the return value if you want to see if the kref is now
> - * gone, not present.
> - */
> -int kref_sub(struct kref *kref, unsigned int count,
> - void (*release)(struct kref *kref))
> -{
> - WARN_ON(release == NULL);
> - WARN_ON(release == (void (*)(struct kref *))kfree);
> -
> - if (atomic_sub_and_test((int) count, &kref->refcount)) {
> - release(kref);
> - return 1;
> - }
> - return 0;
> -}
> -
> -EXPORT_SYMBOL(kref_init);
> -EXPORT_SYMBOL(kref_get);
> -EXPORT_SYMBOL(kref_put);
> -EXPORT_SYMBOL(kref_sub);
> Index: linux-2.6/lib/Makefile
> ===================================================================
> --- linux-2.6.orig/lib/Makefile
> +++ linux-2.6/lib/Makefile
> @@ -17,7 +17,7 @@ lib-y := ctype.o string.o vsprintf.o cmd
> lib-$(CONFIG_MMU) += ioremap.o
> lib-$(CONFIG_SMP) += cpumask.o
>
> -lib-y += kobject.o kref.o klist.o
> +lib-y += kobject.o klist.o
>
> obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
> bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
>
>
> --
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thanks,
--
Ming Lei
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