Hi Arnd,
Thanks for your review!
---- On Mon, 11 Jul 2022 21:36:12 +0800 Arnd Bergmann <arnd@xxxxxxxx> wrote ---
> 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.
When you say "user visible", do you mean the config can be dropped or something else like Kconfig type other than bool?
>
> > @@ -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
>
These will be fixed in v2.
Regards,
Li
