Re: [PATCH v2 3/7] mm/memory_hotplug: prepare passing flags to add_memory() and friends

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



David Hildenbrand <david@xxxxxxxxxx> writes:
> On 09.09.20 09:17, Greg Kroah-Hartman wrote:
>> On Tue, Sep 08, 2020 at 10:10:08PM +0200, David Hildenbrand wrote:
>>> We soon want to pass flags, e.g., to mark added System RAM resources.
>>> mergeable. Prepare for that.
>> 
>> What are these random "flags", and how do we know what should be passed
>> to them?
>> 
>> Why not make this an enumerated type so that we know it all works
>> properly, like the GPF_* flags are?  Passing around a random unsigned
>> long feels very odd/broken...
>
> Agreed, an enum (mhp_flags) seems to give a better hint what can
> actually be passed. Thanks!

You probably know this but ...

Just using a C enum doesn't get you any type safety.

You can get some checking via sparse by using __bitwise, which is what
gfp_t does. You don't actually have to use an enum for that, it works
with #defines also.

Or you can wrap the flag in a struct, the way atomic_t does, and then
the compiler will prevent passing plain integers in place of your custom
type.

cheers



[Index of Archives]     [Linux IBM ACPI]     [Linux Power Management]     [Linux Kernel]     [Linux Laptop]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]

  Powered by Linux