cvs commit: src/sys/dev/mxge if_mxge.c

[Scott Long]

Scott Long wrote:
> Andrew Gallatin wrote:
>> gallatin    2007-01-31 15:47:44 UTC
>>
>>   FreeBSD src repository
>>
>>   Modified files:
>>     sys/dev/mxge         if_mxge.c   Log:
>>   destroy busdma maps even if they are NULL, so as to avoid leaking
>>   busdma tags.
>>     Revision  Changes    Path
>>   1.19      +16 -18    src/sys/dev/mxge/if_mxge.c
> 
> Yeah, I can't stress enough that busdma maps are opaque handles and
> should always be handled like they are valid.  It's only an
> implementation detail that they are often NULL on i386 and amd64.
> 
> Scott
> 

Oh, I forgot to add that it's my intention to make them no longer be
NULL on any platform.  They need to hold the S/G list during a load
operation; right now that list is stored in the tag, which in effect
serializes drivers on whatever lock is protecting the tag.  It also
makes compound load operations more fragile.  I just need to audit
every single driver in the tree to make sure that there aren't
assumptions being made about the map evaluating to NULL.

Scott