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Re: mbuf data access (repost)
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Re: mbuf data access (repost)


  • Subject: Re: mbuf data access (repost)
  • From: Josh Graessley <email@hidden>
  • Date: Tue, 13 Jun 2006 12:46:34 -0700


Peter is correct. You can use mbuf_mclhasreference to determine if you need to copy the mbuf before modifying the data.


To make the copy, you can use mbuf_dup.

-josh

On Jun 13, 2006, at 11:30 AM, Peter Lovell wrote:


On Jun 12, 2006, at 4:46 AM, email@hidden wrote:

On 7 juin 06, at 19:26, Josh Graessley wrote:



mbuf_len like mbuf_data works whether or not MBUF_EXT is set. MBUF_EXT just indicates that the actual implementation of the mbuf is storing the data in an external cluster and not in the mbuf data structure itself. The one reason this would be important to a client of the mbuf is the case where you may modify data. In some cases, the reference to the external cluster may be shared.



Is there a way to find out if those mbufs are shared ?



It looks to me as though mbuf_mclhasreference may do what you want. That's in the code but doesn't seem to have a documentation entry. Check bsd/kern/kpi_mbuf.c to see if it's what you need

Cheers.....Peter
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  • Follow-Ups:
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 >Re:mbuf data access (repost) (From: "email@hidden" <email@hidden>)
 >Re: mbuf data access (repost) (From: Peter Lovell <email@hidden>)

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