Re: [PATCH 2/4] msi vector targeting abstractions

Matthew Wilcox
2005-12-21T19:05:58Z

On Wed, Dec 21, 2005 at 12:42:41PM -0600, Mark Maule wrote:
> {
> struct msi_desc *entry;
> - struct msg_address address;
> + uint32_t address_hi, address_lo;

Don't use uint32_t. Use u32 instead.

> @@ -108,28 +125,38 @@
> if (!(pos = pci_find_capability(entry->dev, PCI_CAP_ID_MSI)))
> return;
>
> + pci_read_config_dword(entry->dev, msi_upper_address_reg(pos),
> + &address_hi);
> pci_read_config_dword(entry->dev, msi_lower_address_reg(pos),
> - &address.lo_address.value);
> - address.lo_address.value &= MSI_ADDRESS_DEST_ID_MASK;
> - address.lo_address.value |= (cpu_physical_id(dest_cpu) <<
> - MSI_TARGET_CPU_SHIFT);
> - entry->msi_attrib.current_cpu = cpu_physical_id(dest_cpu);
> + &address_lo);
> +
> + msi_callouts.msi_target(vector, dest_cpu,
> + &address_hi, &address_lo);
> +
> + pci_write_config_dword(entry->dev, msi_upper_address_reg(pos),
> + address_hi);
> pci_write_config_dword(entry->dev, msi_lower_address_reg(pos),
> - address.lo_address.value);
> + address_lo);

But actually, I don't understand why you don't just pass a msg_address
pointer to msi_target instead.

(last two points apply throughtout this patch)

>
> + (*msi_callouts.msi_teardown)(vector);
> +

Yuck. There's a reason C allows you to call through function pointers as if
they were functions.

> +int
> +msi_register_callouts(struct msi_callouts *co)
> +{
> + msi_callouts = *co; /* structure copy */
> + return 0;

Why do it this way instead of having a pointer to a struct?

> -struct msg_data {
> +union msg_data {
> + struct {

How about leaving struct msg_data alone and adding

union good_name {
struct msg_data;
u32 value;
}

Or possibly struct msg_data should just be deleted and we should use
shift/mask to access the contents of it. ISTR GCC handled that much
better.