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

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hi Vignesh Raghavendra,

On 2020/1/23 下午12:24, 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");





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