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Commit fb13a28b authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Linus Torvalds
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[PATCH] swsusp: struct snapshot_handle cleanup 



Add comments describing struct snapshot_handle and its members, change the
confusing name of its member 'page' to 'cur'.

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ae83c5ee

kernel/power/power.h

+56 −8
Original line number Diff line number Diff line
@@ -50,17 +50,65 @@ extern asmlinkage int swsusp_arch_resume(void); 


extern unsigned int count_data_pages(void);



/**

 *	Auxiliary structure used for reading the snapshot image data and

 *	metadata from and writing them to the list of page backup entries

 *	(PBEs) which is the main data structure of swsusp.

 *

 *	Using struct snapshot_handle we can transfer the image, including its

 *	metadata, as a continuous sequence of bytes with the help of

 *	snapshot_read_next() and snapshot_write_next().

 *

 *	The code that writes the image to a storage or transfers it to

 *	the user land is required to use snapshot_read_next() for this

 *	purpose and it should not make any assumptions regarding the internal

 *	structure of the image.  Similarly, the code that reads the image from

 *	a storage or transfers it from the user land is required to use

 *	snapshot_write_next().

 *

 *	This may allow us to change the internal structure of the image

 *	in the future with considerably less effort.

 */



struct snapshot_handle {

	loff_t		offset;

	unsigned int	page;

	unsigned int	page_offset;

	unsigned int	prev;

	struct pbe	*pbe, *last_pbe;

	void		*buffer;

	unsigned int	buf_offset;

	int		sync_read;

	loff_t		offset;	/* number of the last byte ready for reading

				 * or writing in the sequence

				 */

	unsigned int	cur;	/* number of the block of PAGE_SIZE bytes the

				 * next operation will refer to (ie. current)

				 */

	unsigned int	cur_offset;	/* offset with respect to the current

					 * block (for the next operation)

					 */

	unsigned int	prev;	/* number of the block of PAGE_SIZE bytes that

				 * was the current one previously

				 */

	struct pbe	*pbe;	/* PBE that corresponds to 'buffer' */

	struct pbe	*last_pbe;	/* When the image is restored (eg. read

					 * from disk) we can store some image

					 * data directly in the page frames

					 * in which they were before suspend.

					 * In such a case the PBEs that

					 * correspond to them will be unused.

					 * This is the last PBE, so far, that

					 * does not correspond to such data.

					 */

	void		*buffer;	/* address of the block to read from

					 * or write to

					 */

	unsigned int	buf_offset;	/* location to read from or write to,

					 * given as a displacement from 'buffer'

					 */

	int		sync_read;	/* Set to one to notify the caller of

					 * snapshot_write_next() that it may

					 * need to call wait_on_bio_chain()

					 */

};



/* This macro returns the address from/to which the caller of

 * snapshot_read_next()/snapshot_write_next() is allowed to

 * read/write data after the function returns

 */

#define data_of(handle)	((handle).buffer + (handle).buf_offset)



extern int snapshot_read_next(struct snapshot_handle *handle, size_t count);

kernel/power/snapshot.c

+20 −20
Original line number Diff line number Diff line
@@ -555,7 +555,7 @@ static inline struct pbe *pack_orig_addresses(unsigned long *buf, struct pbe *pb 


int snapshot_read_next(struct snapshot_handle *handle, size_t count)

{

	if (handle->page > nr_meta_pages + nr_copy_pages)

	if (handle->cur > nr_meta_pages + nr_copy_pages)

		return 0;

	if (!buffer) {

		/* This makes the buffer be freed by swsusp_free() */
@@ -568,8 +568,8 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count) 
		handle->buffer = buffer;

		handle->pbe = pagedir_nosave;

	}

	if (handle->prev < handle->page) {

		if (handle->page <= nr_meta_pages) {

	if (handle->prev < handle->cur) {

		if (handle->cur <= nr_meta_pages) {

			handle->pbe = pack_orig_addresses(buffer, handle->pbe);

			if (!handle->pbe)

				handle->pbe = pagedir_nosave;
@@ -577,15 +577,15 @@ int snapshot_read_next(struct snapshot_handle *handle, size_t count) 
			handle->buffer = (void *)handle->pbe->address;

			handle->pbe = handle->pbe->next;

		}

		handle->prev = handle->page;

		handle->prev = handle->cur;

	}

	handle->buf_offset = handle->page_offset;

	if (handle->page_offset + count >= PAGE_SIZE) {

		count = PAGE_SIZE - handle->page_offset;

		handle->page_offset = 0;

		handle->page++;

	handle->buf_offset = handle->cur_offset;

	if (handle->cur_offset + count >= PAGE_SIZE) {

		count = PAGE_SIZE - handle->cur_offset;

		handle->cur_offset = 0;

		handle->cur++;

	} else {

		handle->page_offset += count;

		handle->cur_offset += count;

	}

	handle->offset += count;

	return count;
@@ -820,7 +820,7 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) 
{

	int error = 0;



	if (handle->prev && handle->page > nr_meta_pages + nr_copy_pages)

	if (handle->prev && handle->cur > nr_meta_pages + nr_copy_pages)

		return 0;

	if (!buffer) {

		/* This makes the buffer be freed by swsusp_free() */
@@ -831,7 +831,7 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) 
	if (!handle->offset)

		handle->buffer = buffer;

	handle->sync_read = 1;

	if (handle->prev < handle->page) {

	if (handle->prev < handle->cur) {

		if (!handle->prev) {

			error = load_header(handle,

					(struct swsusp_info *)buffer);
@@ -854,15 +854,15 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) 
			handle->buffer = get_buffer(handle);

			handle->sync_read = 0;

		}

		handle->prev = handle->page;

		handle->prev = handle->cur;

	}

	handle->buf_offset = handle->page_offset;

	if (handle->page_offset + count >= PAGE_SIZE) {

		count = PAGE_SIZE - handle->page_offset;

		handle->page_offset = 0;

		handle->page++;

	handle->buf_offset = handle->cur_offset;

	if (handle->cur_offset + count >= PAGE_SIZE) {

		count = PAGE_SIZE - handle->cur_offset;

		handle->cur_offset = 0;

		handle->cur++;

	} else {

		handle->page_offset += count;

		handle->cur_offset += count;

	}

	handle->offset += count;

	return count;
@@ -871,5 +871,5 @@ int snapshot_write_next(struct snapshot_handle *handle, size_t count) 
int snapshot_image_loaded(struct snapshot_handle *handle)

{

	return !(!handle->pbe || handle->pbe->next || !nr_copy_pages ||

		handle->page <= nr_meta_pages + nr_copy_pages);

		handle->cur <= nr_meta_pages + nr_copy_pages);

}