Re: [PATCH v1 11/11] mtd: new support oops logger based on pstore/blk

[liaoweixiong]

hi Vignesh Raghavendra,

On 2020/1/23 äå12:24, Vignesh Raghavendra wrote:
> Hi
>
> On 20/01/20 6:33 am, WeiXiong Liao wrote:
> [...]
> > +static inline int mtdpstore_panic_block_isbad(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	struct mtd_info *mtd = cxt->mtd;
> > +	u64 blknum = div_u64(off, mtd->erasesize);
> > +
> > +	return test_bit(blknum, cxt->badmap);
> > +}
> > +
> > +static inline void mtdpstore_mark_used(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +
> > +	pr_debug("mark zone %llu used\n", zonenum);
>
> Please replace pr_*() with dev_*() throughout the patch. Device pointer
> should be available via struct mtd_info

OK. I will fix it later. Thank you.

> Regards
> Vignesh
>
> > +	set_bit(zonenum, cxt->usedmap);
> > +}
> > +
> > +static inline void mtdpstore_mark_unused(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +
> > +	pr_debug("mark zone %llu unused\n", zonenum);
> > +	clear_bit(zonenum, cxt->usedmap);
> > +}
> > +
> > +static inline void mtdpstore_block_mark_unused(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
> > +
> > +	while (zonecnt > 0) {
> > +		pr_debug("mark zone %llu unused\n", zonenum);
> > +		clear_bit(zonenum, cxt->usedmap);
> > +		zonenum++;
> > +		zonecnt--;
> > +	}
> > +}
> > +
> > +static inline int mtdpstore_is_used(struct mtdpstore_context *cxt, loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +	u64 blknum = div_u64(off, cxt->mtd->erasesize);
> > +
> > +	if (test_bit(blknum, cxt->badmap))
> > +		return true;
> > +	return test_bit(zonenum, cxt->usedmap);
> > +}
> > +
> > +static int mtdpstore_block_is_used(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
> > +
> > +	while (zonecnt > 0) {
> > +		if (test_bit(zonenum, cxt->usedmap))
> > +			return true;
> > +		zonenum++;
> > +		zonecnt--;
> > +	}
> > +	return false;
> > +}
> > +
> > +static int mtdpstore_is_empty(struct mtdpstore_context *cxt, char *buf,
> > +		size_t size)
> > +{
> > +	struct mtd_info *mtd = cxt->mtd;
> > +	size_t sz;
> > +	int i;
> > +
> > +	sz = min_t(uint32_t, size, mtd->writesize / 4);
> > +	for (i = 0; i < sz; i++) {
> > +		if (buf[i] != (char)0xFF)
> > +			return false;
> > +	}
> > +	return true;
> > +}
> > +
> > +static void mtdpstore_mark_removed(struct mtdpstore_context *cxt, loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +
> > +	pr_debug("mark zone %llu removed\n", zonenum);
> > +	set_bit(zonenum, cxt->rmmap);
> > +}
> > +
> > +static void mtdpstore_block_clear_removed(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
> > +
> > +	while (zonecnt > 0) {
> > +		clear_bit(zonenum, cxt->rmmap);
> > +		zonenum++;
> > +		zonecnt--;
> > +	}
> > +}
> > +
> > +static int mtdpstore_block_is_removed(struct mtdpstore_context *cxt,
> > +		loff_t off)
> > +{
> > +	u64 zonenum = div_u64(off, cxt->bo_info.dmesg_size);
> > +	u32 zonecnt = cxt->mtd->erasesize / cxt->bo_info.dmesg_size;
> > +
> > +	while (zonecnt > 0) {
> > +		if (test_bit(zonenum, cxt->rmmap))
> > +			return true;
> > +		zonenum++;
> > +		zonecnt--;
> > +	}
> > +	return false;
> > +}
> > +
> > +static int mtdpstore_erase_do(struct mtdpstore_context *cxt, loff_t off)
> > +{
> > +	struct erase_info erase;
> > +	int ret;
> > +
> > +	pr_debug("try to erase off 0x%llx\n", off);
> > +	erase.len = cxt->mtd->erasesize;
> > +	erase.addr = off;
> > +	ret = mtd_erase(cxt->mtd, &erase);
> > +	if (!ret)
> > +		mtdpstore_block_clear_removed(cxt, off);
> > +	else
> > +		pr_err("erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
> > +		       (unsigned long long)erase.addr,
> > +		       (unsigned long long)erase.len, cxt->bo_info.device);
> > +	return ret;
> > +}
> > +
> > +/*
> > + * called while removing file
> > + *
> > + * Avoiding over erasing, do erase only when all zones are removed or unused.
> > + * Ensure to remove when unregister by reading, erasing and wrtiing back.
> > + */
> > +static ssize_t mtdpstore_erase(size_t size, loff_t off)
> > +{
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +
> > +	if (mtdpstore_block_isbad(cxt, off))
> > +		return -EIO;
> > +
> > +	mtdpstore_mark_unused(cxt, off);
> > +
> > +	if (likely(mtdpstore_block_is_used(cxt, off))) {
> > +		mtdpstore_mark_removed(cxt, off);
> > +		return 0;
> > +	}
> > +
> > +	/* all zones are unused, erase it */
> > +	off = ALIGN_DOWN(off, cxt->mtd->erasesize);
> > +	return mtdpstore_erase_do(cxt, off);
> > +}
> > +
> > +/*
> > + * What is securety for mtdpstore?
> > + * As there is no erase for panic case, we should ensure at least one zone
> > + * is writable. Otherwise, panic write will be failed.
> > + * If zone is used, write operation will return -ENEXT, which means that
> > + * pstore/blk will try one by one until get a empty zone. So, it's no need
> > + * to ensure next zone is empty, but at least one.
> > + */
> > +static int mtdpstore_security(struct mtdpstore_context *cxt, loff_t off)
> > +{
> > +	int ret = 0, i;
> > +	u32 zonenum = (u32)div_u64(off, cxt->bo_info.dmesg_size);
> > +	u32 zonecnt = (u32)div_u64(cxt->mtd->size, cxt->bo_info.dmesg_size);
> > +	u32 blkcnt = (u32)div_u64(cxt->mtd->size, cxt->mtd->erasesize);
> > +	u32 erasesize = cxt->mtd->erasesize;
> > +
> > +	for (i = 0; i < zonecnt; i++) {
> > +		u32 num = (zonenum + i) % zonecnt;
> > +
> > +		/* found empty zone */
> > +		if (!test_bit(num, cxt->usedmap))
> > +			return 0;
> > +	}
> > +
> > +	/* If there is no any empty zone, we have no way but to do erase */
> > +	off = ALIGN_DOWN(off, erasesize);
> > +	while (blkcnt--) {
> > +		div64_u64_rem(off + erasesize, cxt->mtd->size, (u64 *)&off);
> > +
> > +		if (mtdpstore_block_isbad(cxt, off))
> > +			continue;
> > +
> > +		ret = mtdpstore_erase_do(cxt, off);
> > +		if (!ret) {
> > +			mtdpstore_block_mark_unused(cxt, off);
> > +			break;
> > +		}
> > +	}
> > +
> > +	if (ret)
> > +		pr_err("all blocks bad!\n");
> > +	pr_debug("end security\n");
> > +	return ret;
> > +}
> > +
> > +static ssize_t mtdpstore_write(const char *buf, size_t size, loff_t off)
> > +{
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +	size_t retlen;
> > +	int ret;
> > +
> > +	if (mtdpstore_block_isbad(cxt, off))
> > +		return -ENEXT;
> > +
> > +	/* zone is used, please try next one */
> > +	if (mtdpstore_is_used(cxt, off))
> > +		return -ENEXT;
> > +
> > +	pr_debug("try to write off 0x%llx size %zu\n", off, size);
> > +	ret = mtd_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
> > +	if (ret < 0 || retlen != size) {
> > +		pr_err("write failure at %lld (%zu of %zu written), err %d\n",
> > +				off, retlen, size, ret);
> > +		return -EIO;
> > +	}
> > +	mtdpstore_mark_used(cxt, off);
> > +
> > +	mtdpstore_security(cxt, off);
> > +	return retlen;
> > +}
> > +
> > +/*
> > + * All zones will be read as pstore/blk will read zone one by one when do
> > + * recover.
> > + */
> > +static ssize_t mtdpstore_read(char *buf, size_t size, loff_t off)
> > +{
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +	size_t retlen;
> > +	int ret;
> > +
> > +	if (mtdpstore_block_isbad(cxt, off))
> > +		return -ENEXT;
> > +
> > +	pr_debug("try to read off 0x%llx size %zu\n", off, size);
> > +	ret = mtd_read(cxt->mtd, off, size, &retlen, (u_char *)buf);
> > +	if ((ret < 0 && !mtd_is_bitflip(ret)) || size != retlen)  {
> > +		pr_err("read failure at %lld (%zu of %zu read), err %d\n",
> > +				off, retlen, size, ret);
> > +		return -EIO;
> > +	}
> > +
> > +	if (mtdpstore_is_empty(cxt, buf, size))
> > +		mtdpstore_mark_unused(cxt, off);
> > +	else
> > +		mtdpstore_mark_used(cxt, off);
> > +
> > +	mtdpstore_security(cxt, off);
> > +	return retlen;
> > +}
> > +
> > +static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off)
> > +{
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +	size_t retlen;
> > +	int ret;
> > +
> > +	if (mtdpstore_panic_block_isbad(cxt, off))
> > +		return -ENEXT;
> > +
> > +	/* zone is used, please try next one */
> > +	if (mtdpstore_is_used(cxt, off))
> > +		return -ENEXT;
> > +
> > +	ret = mtd_panic_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
> > +	if (ret < 0 || size != retlen) {
> > +		pr_err("panic write failure at %lld (%zu of %zu read), err %d\n",
> > +				off, retlen, size, ret);
> > +		return -EIO;
> > +	}
> > +	mtdpstore_mark_used(cxt, off);
> > +
> > +	return retlen;
> > +}
> > +
> > +static void mtdpstore_notify_add(struct mtd_info *mtd)
> > +{
> > +	int ret;
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +	struct blkoops_info *info = &cxt->bo_info;
> > +	unsigned long longcnt;
> > +
> > +	if (!strcmp(mtd->name, info->device))
> > +		cxt->index = mtd->index;
> > +
> > +	if (mtd->index != cxt->index || cxt->index < 0)
> > +		return;
> > +
> > +	pr_debug("found matching MTD device %s\n", mtd->name);
> > +
> > +	if (mtd->size < info->dmesg_size * 2) {
> > +		pr_err("MTD partition %d not big enough\n", mtd->index);
> > +		return;
> > +	}
> > +	if (mtd->erasesize < info->dmesg_size) {
> > +		pr_err("eraseblock size of MTD partition %d too small\n",
> > +				mtd->index);
> > +		return;
> > +	}
> > +	if (unlikely(info->dmesg_size % mtd->writesize)) {
> > +		pr_err("record size %lu KB must align to write size %d KB\n",
> > +				info->dmesg_size / 1024,
> > +				mtd->writesize / 1024);
> > +		return;
> > +	}
> > +	if (unlikely(mtd->size > MTDPSTORE_MAX_MTD_SIZE)) {
> > +		pr_err("mtd%d is too large (limit is %d MiB)\n",
> > +				mtd->index,
> > +				MTDPSTORE_MAX_MTD_SIZE / 1024 / 1024);
> > +		return;
> > +	}
> > +
> > +	longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->dmesg_size));
> > +	cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
> > +	cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
> > +
> > +	longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
> > +	cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
> > +
> > +	cxt->bo_dev.total_size = mtd->size;
> > +	/* just support dmesg right now */
> > +	cxt->bo_dev.flags = BLKOOPS_DEV_SUPPORT_DMESG;
> > +	cxt->bo_dev.read = mtdpstore_read;
> > +	cxt->bo_dev.write = mtdpstore_write;
> > +	cxt->bo_dev.erase = mtdpstore_erase;
> > +	cxt->bo_dev.panic_write = mtdpstore_panic_write;
> > +
> > +	ret = blkoops_register_device(&cxt->bo_dev);
> > +	if (ret) {
> > +		pr_err("mtd%d register to blkoops failed\n", mtd->index);
> > +		return;
> > +	}
> > +	cxt->mtd = mtd;
> > +	pr_info("Attached to MTD device %d\n", mtd->index);
> > +}
> > +
> > +static int mtdpstore_flush_removed_do(struct mtdpstore_context *cxt,
> > +		loff_t off, size_t size)
> > +{
> > +	struct mtd_info *mtd = cxt->mtd;
> > +	u_char *buf;
> > +	int ret;
> > +	size_t retlen;
> > +	struct erase_info erase;
> > +
> > +	buf = kmalloc(mtd->erasesize, GFP_KERNEL);
> > +	if (!buf)
> > +		return -ENOMEM;
> > +
> > +	/* 1st. read to cache */
> > +	ret = mtd_read(mtd, off, mtd->erasesize, &retlen, buf);
> > +	if (ret || retlen != mtd->erasesize)
> > +		goto free;
> > +
> > +	/* 2nd. erase block */
> > +	erase.len = mtd->erasesize;
> > +	erase.addr = off;
> > +	ret = mtd_erase(mtd, &erase);
> > +	if (ret)
> > +		goto free;
> > +
> > +	/* 3rd. write back */
> > +	while (size) {
> > +		unsigned int zonesize = cxt->bo_info.dmesg_size;
> > +
> > +		/* remove must clear used bit */
> > +		if (mtdpstore_is_used(cxt, off))
> > +			mtd_write(mtd, off, zonesize, &retlen, buf);
> > +
> > +		off += zonesize;
> > +		size -= min_t(unsigned int, zonesize, size);
> > +	}
> > +
> > +free:
> > +	kfree(buf);
> > +	return ret;
> > +}
> > +
> > +static int mtdpstore_flush_removed(struct mtdpstore_context *cxt)
> > +{
> > +	struct mtd_info *mtd = cxt->mtd;
> > +	int ret;
> > +	loff_t off;
> > +	u32 blkcnt = (u32)div_u64(mtd->size, mtd->erasesize);
> > +
> > +	for (off = 0; blkcnt > 0; blkcnt--, off += mtd->erasesize) {
> > +		ret = mtdpstore_block_is_removed(cxt, off);
> > +		if (!ret) {
> > +			off += mtd->erasesize;
> > +			continue;
> > +		}
> > +
> > +		ret = mtdpstore_flush_removed_do(cxt, off, mtd->erasesize);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +	return 0;
> > +}
> > +
> > +static void mtdpstore_notify_remove(struct mtd_info *mtd)
> > +{
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +
> > +	if (mtd->index != cxt->index || cxt->index < 0)
> > +		return;
> > +
> > +	mtdpstore_flush_removed(cxt);
> > +
> > +	blkoops_unregister_device(&cxt->bo_dev);
> > +	kfree(cxt->badmap);
> > +	kfree(cxt->usedmap);
> > +	kfree(cxt->rmmap);
> > +	cxt->mtd = NULL;
> > +	cxt->index = -1;
> > +}
> > +
> > +static struct mtd_notifier mtdpstore_notifier = {
> > +	.add	= mtdpstore_notify_add,
> > +	.remove	= mtdpstore_notify_remove,
> > +};
> > +
> > +static int __init mtdpstore_init(void)
> > +{
> > +	int ret;
> > +	struct mtdpstore_context *cxt = &oops_cxt;
> > +	struct blkoops_info *info = &cxt->bo_info;
> > +
> > +	ret = blkoops_info(info);
> > +	if (unlikely(ret))
> > +		return ret;
> > +
> > +	if (strlen(info->device) == 0) {
> > +		pr_err("mtd device must be supplied\n");
> > +		return -EINVAL;
> > +	}
> > +	if (!info->dmesg_size) {
> > +		pr_err("no recorder enabled\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* Setup the MTD device to use */
> > +	ret = kstrtoint((char *)info->device, 0, &cxt->index);
> > +	if (ret)
> > +		cxt->index = -1;
> > +
> > +	register_mtd_user(&mtdpstore_notifier);
> > +	return 0;
> > +}
> > +module_init(mtdpstore_init);
> > +
> > +static void __exit mtdpstore_exit(void)
> > +{
> > +	unregister_mtd_user(&mtdpstore_notifier);
> > +}
> > +module_exit(mtdpstore_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");