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Re: CVS commit: src/sys/net



christos%astron.com@localhost (Christos Zoulas) writes:

> In article <20151210081103.E0FBBFB83%cvs.NetBSD.org@localhost>,
> Kengo NAKAHARA <source-changes-d%NetBSD.org@localhost> wrote:
>>-=-=-=-=-=-
>>
>>Module Name:	src
>>Committed By:	knakahara
>>Date:		Thu Dec 10 08:11:03 UTC 2015
>>
>>Modified Files:
>>	src/sys/net: if_gif.c
>>
>>Log Message:
>>kmem_zalloc(, KM_SLEEP) must not return NULL.
>
> I would like to solicit opinions about this change and form a general
> policy.
>
> 1. I would like to reduce the use of KASSERT in the kernel, specially
> in situations like thee above where the test can be centralized (inside
> kmem_alloc) and avoided without being fatal.
>
> 2. Static analyzer models understand allocators, but they are not
> smart enough to determine under which situations they can fail. I
> believe even kmem_alloc with KM_SLEEP can fail when the size is
> large enough.
>
> So I propose to always check the return value of allocators with
> an 'if' and not a KASSERT.

I think that a function needs to have a contract specified in a contract
(and perhaps static analyzer markup).  Code should never KASSERT for
anything that can not be argued (statically shown) to be always true
given contracts.  So I agree with you.

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