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Commit 43b043e7 authored by Josselin Costanzi's avatar Josselin Costanzi Committed by Artem Bityutskiy
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UBI: reduce memory consumption 



Remove the pre-allocated 'peb_buf2' buffer because we do not really need it.
The only reason UBI has it is to check that the data were written correctly.
But we do not have to have 2 buffers for this and waste RAM - we can just
compare CRC checksums instead. This reduces UBI memory consumption.

Artem bityutskiy: massaged the patch and commit message

Signed-off-by: default avatarJosselin Costanzi <josselin.costanzi@mobile-devices.fr>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
parent 7eb3aa65

drivers/mtd/ubi/build.c

+0 −6
Original line number Diff line number Diff line
@@ -949,10 +949,6 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset) 
	if (!ubi->peb_buf1)

		goto out_free;



	ubi->peb_buf2 = vmalloc(ubi->peb_size);

	if (!ubi->peb_buf2)

		goto out_free;



	err = ubi_debugging_init_dev(ubi);

	if (err)

		goto out_free;
@@ -1030,7 +1026,6 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset) 
	ubi_debugging_exit_dev(ubi);

out_free:

	vfree(ubi->peb_buf1);

	vfree(ubi->peb_buf2);

	if (ref)

		put_device(&ubi->dev);

	else
@@ -1102,7 +1097,6 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway) 
	put_mtd_device(ubi->mtd);

	ubi_debugging_exit_dev(ubi);

	vfree(ubi->peb_buf1);

	vfree(ubi->peb_buf2);

	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);

	put_device(&ubi->dev);

	return 0;

drivers/mtd/ubi/eba.c

+3 −3
Original line number Diff line number Diff line
@@ -1134,8 +1134,8 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to, 
		 * We've written the data and are going to read it back to make

		 * sure it was written correctly.

		 */



		err = ubi_io_read_data(ubi, ubi->peb_buf2, to, 0, aldata_size);

		memset(ubi->peb_buf1, 0xFF, aldata_size);

		err = ubi_io_read_data(ubi, ubi->peb_buf1, to, 0, aldata_size);

		if (err) {

			if (err != UBI_IO_BITFLIPS) {

				ubi_warn("error %d while reading data back "
@@ -1149,7 +1149,7 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to, 


		cond_resched();



		if (memcmp(ubi->peb_buf1, ubi->peb_buf2, aldata_size)) {

		if (crc != crc32(UBI_CRC32_INIT, ubi->peb_buf1, data_size)) {

			ubi_warn("read data back from PEB %d and it is "

				 "different", to);

			err = -EINVAL;

drivers/mtd/ubi/ubi.h

+1 −3
Original line number Diff line number Diff line
@@ -388,8 +388,7 @@ struct ubi_wl_entry; 
 * @mtd: MTD device descriptor

 *

 * @peb_buf1: a buffer of PEB size used for different purposes

 * @peb_buf2: another buffer of PEB size used for different purposes

 * @buf_mutex: protects @peb_buf1 and @peb_buf2

 * @buf_mutex: protects @peb_buf1

 * @ckvol_mutex: serializes static volume checking when opening

 *

 * @dbg: debugging information for this UBI device
@@ -472,7 +471,6 @@ struct ubi_device { 
	struct mtd_info *mtd;



	void *peb_buf1;

	void *peb_buf2;

	struct mutex buf_mutex;

	struct mutex ckvol_mutex;