Messages in this thread Patch in this message | | | Date | Mon, 26 Jul 2004 20:18:56 +0530 | From | Ravikiran G Thirumalai <> | Subject | [patch] Add kref_read and kref_put_last primitives |
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Greg, Here is a patch to add kref_read and kref_put_last. These primitives were needed to change files_struct.f_count refcounter to use kref api.
kref_put_last is needed sometimes when a refcount might have an unconventional release which needs more than the refcounted object to process object release-- like in the files_struct.f_count conversion patch at __aio_put_req(). The following patch depends on kref shrinkage patches. (which you have already included).
Please include.
Thanks, Kiran
Signed-off-by: Ravikiran Thirumalai <kiran@in.ibm.com>
diff -ruN -X dontdiff2 linux-kref-2.6.7/include/linux/kref.h files_struct-kref-2.6.7/include/linux/kref.h --- linux-kref-2.6.7/include/linux/kref.h 2004-07-26 18:53:24.000000000 +0530 +++ files_struct-kref-2.6.7/include/linux/kref.h 2004-07-26 18:48:43.543549752 +0530 @@ -26,6 +26,8 @@ void kref_init(struct kref *kref); struct kref *kref_get(struct kref *kref); void kref_put(struct kref *kref, void (*release) (struct kref *kref)); +int kref_read(struct kref *kref); +int kref_put_last(struct kref *kref); #endif /* _KREF_H_ */ diff -ruN -X dontdiff2 linux-kref-2.6.7/lib/kref.c files_struct-kref-2.6.7/lib/kref.c --- linux-kref-2.6.7/lib/kref.c 2004-07-26 18:53:24.228879096 +0530 +++ files_struct-kref-2.6.7/lib/kref.c 2004-07-26 19:02:20.782310576 +0530 @@ -54,6 +54,33 @@ } } +/** + * kref_read - Return the refcount value. + * @kref: object. + */ +int kref_read(struct kref *kref) +{ + return atomic_read(&kref->refcount); +} + +/** + * kref_put_last - decrement refcount for object. + * @kref: object. + * + * Decrement the refcount, and if 0 return true. + * Returns false otherwise. + * Use this only if you cannot use kref_put -- when the + * release function of kref_put needs more than just the + * refcounted object. Use of kref_put_last when kref_put + * can do will be frowned upon. + */ +int kref_put_last(struct kref *kref) +{ + return atomic_dec_and_test(&kref->refcount); +} + EXPORT_SYMBOL(kref_init); EXPORT_SYMBOL(kref_get); EXPORT_SYMBOL(kref_put); +EXPORT_SYMBOL(kref_read); +EXPORT_SYMBOL(kref_put_last); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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