Re: rtalloc()/rtfree() problems on CURRENT

From: Andre Oppermann (andre_at_freebsd.org)
Date: 02/24/04

  • Next message: Gleb Smirnoff: "Re: rtalloc()/rtfree() problems on CURRENT" 
    Date: Tue, 24 Feb 2004 13:20:18 +0100
To: Gleb Smirnoff <glebius@cell.sick.ru>

    Gleb Smirnoff wrote:
    >
    > Dear Andre,
    >
    > first, thanks for your feedback.
    >
    > On Tue, Feb 24, 2004 at 11:14:59AM +0100, Andre Oppermann wrote:
    > A> Most of the time, if you don't need a cloned route allocated, you can
    > A> just use rtalloc_ign(&ro, RTF_CLONING) to just get a reference to the
    > A> existing rtentry. Not allocating a new cloned route saves work and
    > A> time for the rtalloc code.
    >
    > Thanks for this hint. So if using rtalloc_ign() I do not need to call rtfree()?

    You still have to call rtfree() to decrement the refcount of the rtentry.

    > Why does this situation is not clear in manpage? :)

    I should update it.

    > A> > if (ro.ro_rt != NULL) {
    > A> > struct rtentry *rt = ro.ro_rt;
    > A> >
    > A> > /* here some read-only things are done with rt */
    > A>
    > A> Maybe you do some nasty things to rt here?
    >
    > Really, I don't :) Exact code is given at end of the mail.

    You indeed do some nasty things.

    > A> > rtfree(ro.ro_rt);
    > A> > }
    > A> >
    > A> > But on CURRENT rtfree() causes panic. Here is backtrace:
    > A> ...
    > A> > Does this mean that something is broken in CURRENT or I am doing something wrong?
    > A>
    > A> rtalloc() and rtfree() are used quite often in the network code and
    > A> otherwise work fine. The odds are high that you are doing something
    > A> wrong.
    >
    > Here is exact code:
    >
    > bzero((caddr_t)&ro, sizeof(ro));
    > sin = (struct sockaddr_in *)&ro.ro_dst;
    > sin->sin_len = sizeof(*sin);
    > sin->sin_family = AF_INET;
    > sin->sin_addr = fle->r.r_dst;
    > rtalloc(&ro);
    > if (ro.ro_rt != NULL) {
    > struct rtentry *rt = ro.ro_rt;
    >
    > /* This is cloned route, use its parent */
    > if (ro.ro_rt->rt_flags & RTF_WASCLONED &&
    > ro.ro_rt->rt_parent)
    > rt = ro.ro_rt->rt_parent;

    With rtalloc() you get a cloned route essentially every time. Use
    rtalloc_ign(&ro, RTF_CLONING) to get the parent route directly.

    > fle->o_ifx = rt->rt_ifp->if_index;
    >
    > if (rt->rt_flags & RTF_GATEWAY &&
    > rt->rt_gateway->sa_family == AF_INET)
    > fle->next_hop =
    > ((struct sockaddr_in *)(rt->rt_gateway))->sin_addr;
    >
    > if (rt_mask(rt))
    > fle->dst_mask =
    > bit_count(((struct sockaddr_in *)rt_mask(rt))->sin_addr.s_addr);
    > else if (rt->rt_flags & RTF_HOST)
    > /* Give up. We can't determine mask :( */
    > fle->dst_mask = 32;
    >
    > rtfree(ro.ro_rt);

    Use the macro RTFREE() instead of rtfree(), it will take care of some
    locking issues.

    > } 

    -- 
Andre
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  • Next message: Gleb Smirnoff: "Re: rtalloc()/rtfree() problems on CURRENT"

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    • Re: rtalloc()/rtfree() problems on CURRENT
      ... A> Most of the time, if you don't need a cloned route allocated, you can ... A> time for the rtalloc code. ... So if using rtalloc_ignI do not need to call rtfree()? ... I don't:) Exact code is given at end of the mail. ...
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    • Re: rtalloc()/rtfree() problems on CURRENT
      ... if you give me some pointers where to look at. ... A> Most of the time, if you don't need a cloned route allocated, you can ... A> time for the rtalloc code. ... A>> But on CURRENT rtfree() causes panic. ...
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      ... > Dear sirs, ... Most of the time, if you don't need a cloned route allocated, you can ... time for the rtalloc code. ... > But on CURRENT rtfree() causes panic. ...
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