Re: [PATCH/RFC] oops and panic message logging to MTD

Artem Bityutskiy
2007-06-19T07:56:07Z

On Mon, 2007-06-18 at 17:31 +0100, Richard Purdie wrote:
> +static int mtdoops_erase_block(struct mtd_info *mtd, int offset)
> +{
> + struct erase_info erase;
> + DECLARE_WAITQUEUE(wait, current);
> + wait_queue_head_t wait_q;
> + int ret;
> +
> + init_waitqueue_head(&wait_q);
> + erase.mtd = mtd;
> + erase.callback = mtdoops_erase_callback;
> + erase.addr = offset;
> + if (mtd->erasesize < OOPS_PAGE_SIZE)
> + erase.len = OOPS_PAGE_SIZE;

It seems to me that your code won't work if mtd->erasesize <
OOPS_PAGE_SIZE anyway, so this check should not be here I guess.

> + ret = mtd->read(mtd, cxt->nextpage * OOPS_PAGE_SIZE, 4,
> + &retlen, (u_char *) &count);
> + if ((retlen != 4) || (ret < 0)) {
> + printk(KERN_ERR "mtdoops: Read failure at %d (%d of 4 read)"
> + ", err %d.\n", cxt->nextpage * OOPS_PAGE_SIZE,
> + retlen, ret);
> + return 1;
> + }

mtd->read() returns -EUCLEAN in case of a correctable bit-flip, ignore
this error code here and elsewhere as well please.

> +static void mtdoops_prepare(struct mtdoops_context *cxt)
> +{
> + struct mtd_info *mtd = cxt->mtd;
> + int i = 0, j, ret, mod;
> +
> + /* We were unregistered */
> + if (!mtd)
> + return;
> +
> + mod = (cxt->nextpage * OOPS_PAGE_SIZE) % mtd->erasesize;
> + if (mod != 0) {
> + cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / OOPS_PAGE_SIZE);
> + if (cxt->nextpage > cxt->oops_pages)
> + cxt->nextpage = 0;
> + }
> +
> + while (mtd->block_isbad &&
> + mtd->block_isbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE)) {

Well, mtd->block_isbad() may return error, unlikely, bu still. You also
ignore the error at other places.

> +badblock:
> + printk(KERN_WARNING "mtdoops: Bad block at %08x\n",
> + cxt->nextpage * OOPS_PAGE_SIZE);
> + i++;
> + cxt->nextpage = cxt->nextpage + (mtd->erasesize / OOPS_PAGE_SIZE);
> + if (cxt->nextpage > cxt->oops_pages)
> + cxt->nextpage = 0;
> + if (i == (cxt->oops_pages / (mtd->erasesize / OOPS_PAGE_SIZE))) {
> + printk(KERN_ERR "mtdoops: All blocks bad!\n");
> + return;
> + }
> + }
> +
> + for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)
> + ret = mtdoops_erase_block(mtd, cxt->nextpage * OOPS_PAGE_SIZE);

Ugh, why do you make it this difficult way instead of

for (all EBs) {
ret = erase()
if (ret == -EIO) {
markbad();
} else
return err;
}

> +
> + if (ret < 0) {
> + if (mtd->block_markbad)
> + mtd->block_markbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE);
> + goto badblock;

Please, mark EB as bad only in case of -EIO. Also, do not ignore error
code of mtd->block_markbad()

Is it possible to re-structure the code and erase/check if EB is bad in
_one_ cycle (thus avoiding this goto which is difficult to understand)?

Surely all you want is to format the partition. So make a loop, skip bad
EBs and erase good ones. In case of erase failure (-EIO) mark the EB as
bad.

> +static int find_next_position(struct mtdoops_context *cxt)
> +{
> + struct mtd_info *mtd = cxt->mtd;
> + int page, maxpos = 0;
> + u32 count, maxcount = 0xffffffff;
> + size_t retlen;
> +
> + for (page = 0; page < cxt->oops_pages; page++) {
> + mtd->read(mtd, page * OOPS_PAGE_SIZE, 4, &retlen, (u_char *) &count);

Please, check return code here.

--
Best regards,
Artem Bityutskiy (Битюцкий Артём)