Commit bcf67e16 authored Jul 10, 2007 by Pavel Emelianov Committed by Linus Torvalds Jul 10, 2007

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: Pavel Emelianov <xemul@openvz.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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

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