From 45465487897a1c6d508b14b904dc5777f7ec7e04 Mon Sep 17 00:00:00 2001 From: Stefani Seibold Date: Mon, 21 Dec 2009 14:37:26 -0800 Subject: kfifo: move struct kfifo in place This is a new generic kernel FIFO implementation. The current kernel fifo API is not very widely used, because it has to many constrains. Only 17 files in the current 2.6.31-rc5 used it. FIFO's are like list's a very basic thing and a kfifo API which handles the most use case would save a lot of development time and memory resources. I think this are the reasons why kfifo is not in use: - The API is to simple, important functions are missing - A fifo can be only allocated dynamically - There is a requirement of a spinlock whether you need it or not - There is no support for data records inside a fifo So I decided to extend the kfifo in a more generic way without blowing up the API to much. The new API has the following benefits: - Generic usage: For kernel internal use and/or device driver. - Provide an API for the most use case. - Slim API: The whole API provides 25 functions. - Linux style habit. - DECLARE_KFIFO, DEFINE_KFIFO and INIT_KFIFO Macros - Direct copy_to_user from the fifo and copy_from_user into the fifo. - The kfifo itself is an in place member of the using data structure, this save an indirection access and does not waste the kernel allocator. - Lockless access: if only one reader and one writer is active on the fifo, which is the common use case, no additional locking is necessary. - Remove spinlock - give the user the freedom of choice what kind of locking to use if one is required. - Ability to handle records. Three type of records are supported: - Variable length records between 0-255 bytes, with a record size field of 1 bytes. - Variable length records between 0-65535 bytes, with a record size field of 2 bytes. - Fixed size records, which no record size field. - Preserve memory resource. - Performance! - Easy to use! This patch: Since most users want to have the kfifo as part of another object, reorganize the code to allow including struct kfifo in another data structure. This requires changing the kfifo_alloc and kfifo_init prototypes so that we pass an existing kfifo pointer into them. This patch changes the implementation and all existing users. [akpm@linux-foundation.org: fix warning] Signed-off-by: Stefani Seibold Acked-by: Greg Kroah-Hartman Acked-by: Mauro Carvalho Chehab Acked-by: Andi Kleen Acked-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kfifo.h | 11 ++++++----- include/scsi/libiscsi.h | 3 ++- include/scsi/libiscsi_tcp.h | 2 +- include/scsi/libsrp.h | 2 +- 4 files changed, 10 insertions(+), 8 deletions(-) (limited to 'include') diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index ad6bdf5..c3f8d82 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -1,6 +1,7 @@ /* - * A simple kernel FIFO implementation. + * A generic kernel FIFO implementation. * + * Copyright (C) 2009 Stefani Seibold * Copyright (C) 2004 Stelian Pop * * This program is free software; you can redistribute it and/or modify @@ -32,10 +33,10 @@ struct kfifo { spinlock_t *lock; /* protects concurrent modifications */ }; -extern struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size, - gfp_t gfp_mask, spinlock_t *lock); -extern struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask, - spinlock_t *lock); +extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer, + unsigned int size, spinlock_t *lock); +extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size, + gfp_t gfp_mask, spinlock_t *lock); extern void kfifo_free(struct kfifo *fifo); extern unsigned int __kfifo_put(struct kfifo *fifo, const unsigned char *buffer, unsigned int len); diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h index 7394e3b..ff92b46 100644 --- a/include/scsi/libiscsi.h +++ b/include/scsi/libiscsi.h @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -231,7 +232,7 @@ struct iscsi_conn { }; struct iscsi_pool { - struct kfifo *queue; /* FIFO Queue */ + struct kfifo queue; /* FIFO Queue */ void **pool; /* Pool of elements */ int max; /* Max number of elements */ }; diff --git a/include/scsi/libiscsi_tcp.h b/include/scsi/libiscsi_tcp.h index 9e3182e..741ae7e 100644 --- a/include/scsi/libiscsi_tcp.h +++ b/include/scsi/libiscsi_tcp.h @@ -80,7 +80,7 @@ struct iscsi_tcp_task { int data_offset; struct iscsi_r2t_info *r2t; /* in progress solict R2T */ struct iscsi_pool r2tpool; - struct kfifo *r2tqueue; + struct kfifo r2tqueue; void *dd_data; }; diff --git a/include/scsi/libsrp.h b/include/scsi/libsrp.h index ba615e4..07e3add 100644 --- a/include/scsi/libsrp.h +++ b/include/scsi/libsrp.h @@ -21,7 +21,7 @@ struct srp_buf { struct srp_queue { void *pool; void *items; - struct kfifo *queue; + struct kfifo queue; spinlock_t lock; }; -- cgit v1.1