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Commit bcf67e16 authored by Pavel Emelianov's avatar Pavel Emelianov Committed by Linus Torvalds
Browse files

Make common helpers for seq_files that work with list_heads 



Many places in kernel use seq_file API to iterate over a regular list_head.
The code for such iteration is identical in all the places, so it's worth
introducing a common helpers.

This makes code about 300 lines smaller:

The first version of this patch made the helper functions static inline
in the seq_file.h header. This patch moves them to the fs/seq_file.c as
Andrew proposed. The vmlinux .text section sizes are as follows:

2.6.22-rc1-mm1:              0x001794d5
with the previous version:   0x00179505
with this patch:             0x00179135

The config file used was make allnoconfig with the "y" inclusion of all
the possible options to make the files modified by the patch compile plus
drivers I have on the test node.

This patch:

Many places in kernel use seq_file API to iterate over a regular list_head.
The code for such iteration is identical in all the places, so it's worth
introducing a common helpers.

Signed-off-by: default avatarPavel Emelianov <xemul@openvz.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c14d444b

fs/seq_file.c

+34 −0
Original line number Diff line number Diff line
@@ -447,3 +447,37 @@ int seq_puts(struct seq_file *m, const char *s) 
	return -1;

}

EXPORT_SYMBOL(seq_puts);



struct list_head *seq_list_start(struct list_head *head, loff_t pos)

{

	struct list_head *lh;



	list_for_each(lh, head)

		if (pos-- == 0)

			return lh;



	return NULL;

}



EXPORT_SYMBOL(seq_list_start);



struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)

{

	if (!pos)

		return head;



	return seq_list_start(head, pos - 1);

}



EXPORT_SYMBOL(seq_list_start_head);



struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)

{

	struct list_head *lh;



	lh = ((struct list_head *)v)->next;

	++*ppos;

	return lh == head ? NULL : lh;

}



EXPORT_SYMBOL(seq_list_next);

include/linux/seq_file.h

+11 −0
Original line number Diff line number Diff line
@@ -50,5 +50,16 @@ int seq_release_private(struct inode *, struct file *); 


#define SEQ_START_TOKEN ((void *)1)



/*

 * Helpers for iteration over list_head-s in seq_files

 */



extern struct list_head *seq_list_start(struct list_head *head,

		loff_t pos);

extern struct list_head *seq_list_start_head(struct list_head *head,

		loff_t pos);

extern struct list_head *seq_list_next(void *v, struct list_head *head,

		loff_t *ppos);



#endif

#endif