On Mon, Jul 11, 2022 at 2:24 PM Li Chen <me@linux.beauty> wrote:
> +config OF_RESERVED_MEM_DIO_SUPPORT
> + bool "add Direct I/O support to reserved_mem"
> + depends on ZONE_DEVICE && ARCH_KEEP_MEMBLOCK
> + help
> + By default, reserved memory don't get struct page support, which
> + means you cannot do Direct I/O from this region. This config takes
> + uses of ZONE_DEVICE and treats rmem as hotplug mem to get struct
> + page and DIO support.
This probably does not need to be user visible, it's enough to select it from
the drivers that need it.
> @@ -72,7 +72,6 @@ void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname,
> rmem->size = size;
>
> reserved_mem_count++;
> - return;
> }
This change is not wrong, but it does not belong into the same patch
as the rest, just drop it.
> +/**
> + * get_reserved_mem_from_dev() - get reserved_mem from a device node
> + * @dev: device pointer
> + *
> + * This function look for reserved_mem from given device.
> + *
> + * Returns a reserved_mem pointer, or NULL on error.
> + */
> +struct reserved_mem *get_reserved_mem_from_dev(struct device *dev)
> +{
> + struct device_node *np = dev_of_node(dev);
> + struct device_node *rmem_np;
> + struct reserved_mem *rmem = NULL;
> +
> + rmem_np = of_parse_phandle(np, "memory-region", 0);
> + if (!rmem_np) {
> + dev_err(dev, "failed to get memory region node\n");
> + return ERR_PTR(-ENODEV);
> + }
> +
> + rmem = of_reserved_mem_lookup(rmem_np);
> + if (!rmem) {
> + dev_err(dev, "Failed to lookup reserved memory\n");
> + return ERR_PTR(EINVAL);
This needs to be a negative error code rather than the positive EINVAL.
No need to initialize rmem=NULL first if you override it here.
> + if (likely(reserved_mem_dio_in_region(pfn << PAGE_SHIFT, PAGE_SIZE, rmem) <
> + 0))
> + goto out;
It's not performance critical, so just drop the 'likely()' and put the
rest into one line.
> + if (page) {
> + *page = pfn_to_page(pfn);
> + get_page(*page);
> + }
> +
> + ret = 0;
> +
> +out:
> + pte_unmap(pte);
> + return ret;
> +}
Should you perhaps return an error when 'page' is NULL?
> +#ifdef CONFIG_OF_RESERVED_MEM_DIO_SUPPORT
> +int reserved_mem_dio_mmap(struct file *file, struct vm_area_struct *vma, struct reserved_mem *rmem);
> +void *reserved_mem_memremap_pages(struct device *dev, struct reserved_mem *rmem);
> +#endif
The '#ifdef' check can be dropped here, declarations are normally
not hidden like this.
Arnd
