On 18.12.2023 15:21, Miquel Raynal wrote:
Hi Rafał,
zajec5@gmail.com wrote on Mon, 18 Dec 2023 14:37:22 +0100:
From: Rafał Miłecki rafal@milecki.pl
This patch moves all generic (NVMEM devices independent) code from NVMEM device driver to NVMEM layout driver. Then it adds a simple NVMEM layout code on top of it.
Thanks to proper layout it's possible to support U-Boot env data stored on any kind of NVMEM device.
For backward compatibility with old DT bindings we need to keep old NVMEM device driver functional. To avoid code duplication a parsing function is exported and reused in it.
Signed-off-by: Rafał Miłecki rafal@milecki.pl
I have a couple of comments about the original driver which gets copy-pasted in the new layout driver, maybe you could clean these (the memory leak should be fixed before the migration so it can be backported easily, the others are just style so it can be done after, I don't mind).
...
+int u_boot_env_parse(struct device *dev, struct nvmem_device *nvmem,
enum u_boot_env_format format)+{
- size_t crc32_data_offset;
- size_t crc32_data_len;
- size_t crc32_offset;
- size_t data_offset;
- size_t data_len;
- size_t dev_size;
- uint32_t crc32;
- uint32_t calc;
- uint8_t *buf;
- int bytes;
- int err;
- dev_size = nvmem_dev_size(nvmem);
- buf = kcalloc(1, dev_size, GFP_KERNEL);
Out of curiosity, why kcalloc(1,...) rather than kzalloc() ?
I used kcalloc() initially as I didn't need buffer to be zeroed.
I see that memory-allocation.rst however says:
And, to be on the safe side it's best to use routines that set memory to zero, like kzalloc().
It's probably close to zero cost to zero that buffer so it could be kzalloc().
- if (!buf) {
err = -ENOMEM;goto err_out;We could directly return ENOMEM here I guess.
- }
- bytes = nvmem_device_read(nvmem, 0, dev_size, buf);
- if (bytes < 0)
return bytes;- else if (bytes != dev_size)
return -EIO;Don't we need to free buf in the above cases?
- switch (format) {
- case U_BOOT_FORMAT_SINGLE:
crc32_offset = offsetof(struct u_boot_env_image_single, crc32);crc32_data_offset = offsetof(struct u_boot_env_image_single, data);data_offset = offsetof(struct u_boot_env_image_single, data);break;- case U_BOOT_FORMAT_REDUNDANT:
crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);data_offset = offsetof(struct u_boot_env_image_redundant, data);break;- case U_BOOT_FORMAT_BROADCOM:
crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);data_offset = offsetof(struct u_boot_env_image_broadcom, data);break;- }
- crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
Looks a bit convoluted, any chances we can use intermediate variables to help decipher this?
- crc32_data_len = dev_size - crc32_data_offset;
- data_len = dev_size - data_offset;
- calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
- if (calc != crc32) {
dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);err = -EINVAL;goto err_kfree;- }
- buf[dev_size - 1] = '\0';
- err = u_boot_env_parse_cells(dev, nvmem, buf, data_offset, data_len);
- if (err)
dev_err(dev, "Failed to add cells: %d\n", err);Please drop this error message, the only reason for which the function call would fail is apparently an ENOMEM case.
+err_kfree:
- kfree(buf);
+err_out:
- return err;
+} +EXPORT_SYMBOL_GPL(u_boot_env_parse);
+static int u_boot_env_add_cells(struct device *dev, struct nvmem_device *nvmem) +{
- const struct of_device_id *match;
- struct device_node *layout_np;
- enum u_boot_env_format format;
- layout_np = of_nvmem_layout_get_container(nvmem);
- if (!layout_np)
return -ENOENT;- match = of_match_node(u_boot_env_of_match_table, layout_np);
- if (!match)
return -ENOENT;- format = (uintptr_t)match->data;
In the core there is currently an unused helper called nvmem_layout_get_match_data() which does that. I think the original intent of this function was to be used in this driver, so depending on your preference, can you please either use it or remove it?
The problem is that nvmem_layout_get_match_data() uses: layout->dev.driver
It doesn't work with layouts driver (since refactoring?) as driver is NULL. That results in NULL pointer dereference when trying to reach of_match_table.
That is why I used u_boot_env_of_match_table directly.
If you know how to fix nvmem_layout_get_match_data() that would be great. Do we need driver_register() somewhere in NVMEM core?
- of_node_put(layout_np);
- return u_boot_env_parse(dev, nvmem, format);
+}
Thanks, Miquèl