Re: [PATCH 6/6] x86/platform/uv/BAU: Add payload descriptor qualifier

From: Thomas Gleixner
Date: Thu Feb 16 2017 - 13:42:37 EST


On Tue, 14 Feb 2017, Andrew Banman wrote:

> On UV4, the destination agent verifies each message by checking the
> descriptor qualifier field of the message payload. Messages without this
> field set to 0x534749 will cause a hub error to assert.

Ok.

What's missing here is:

Seperate the message structs for uv123 and uv4.

> Make this the default action for future architectures, anticipating they
> will have the same requirement.

That's a guarantee to cause issues when uv5 comes around. The way better
solution for this is to do:

enum uv_bau_version {
UV_BAU_V1 = 1,
UV_BAU_V2,
UV_BAU_V3,
UV_BAU_V4,
};

Make bau->uvhub_version type uv_bau_version and use the enum constants in
the switch case. That way the compiler will catch you when you add
UV_BAU_V5 and forgot to update that switch case. That's probably handy to
have that in a few other places which switch on the bau version.

> -struct bau_msg_payload {
> +struct uv1_2_3_bau_msg_payload {
> unsigned long address; /* signifies a page or all
> TLB's of the cpu */
> /* 64 bits */
> @@ -236,6 +238,20 @@ struct bau_msg_payload {
> unsigned int reserved1:32; /* not usable */
> };
>
> +struct uv4_bau_msg_payload {
> + unsigned long address; /* signifies a page or all
> + * TLB's of the cpu
> + */

Please get rid of these tail comments. Either document the struct members
with a comment above the member or even better use the KernelDoc comment
format above the struct to document it.

> + /* 64 bits */

And these are horrible. I had to look twice where this belongs to. I know
you copied existing crap, but that does not make it any better. And really,
if you want to express the size of a member here because you have to talk
to hardware then use the proper types we have for this: u64, u32, u16 ....

> + unsigned short sending_cpu; /* filled in by sender */
> + /* 16 bits */
> + unsigned short acknowledge_count; /* filled in by destination */
> + /* 16 bits */
> + unsigned int reserved1:8; /* not usable */
> + unsigned int qualifier:24; /* descriptor qualifier filled
> + * in by sender


> @@ -1200,6 +1200,7 @@ const struct cpumask *uv_flush_tlb_other
> struct bau_control *bcp;
> unsigned long descriptor_status;
> unsigned long status;
> + unsigned long address;

Same types can go into a single line. No value in wasting lines.

Thanks,

tglx