Re: [REVIEW/TEST] polling(4) changes

From: Bruce Evans (bde_at_zeta.org.au)
Date: 10/01/05

  • Next message: Gavin Atkinson: "vlan(4), bge(4) and bringing parent interface up" 
    Date: Sat, 1 Oct 2005 23:15:32 +1000 (EST)
To: Gleb Smirnoff <glebius@FreeBSD.org>

    On Fri, 30 Sep 2005, Gleb Smirnoff wrote:

    > The attached patch removes:
    > ...
    > - poll in trap feature. Sorry, we can't acquire mutexes in trap(). Anyone
    > used it, anyway?

    This is the most broken part of DEVICE_POLLING (which I consider to be
    mostly broken). Hopefully no one used it. Poll in trap even polled in
    debugger traps, so userland could invoke polling by debugging any program,
    and ether_poll() was reentered if it was debugged (in RELENG_4, there is
    no relevant locking so ether_poll() then just raced itself; in old versions
    of -current I think Giant locking allowed the same since Giant is recursive;
    in -current I think this causes deadlock since poll_mtx is not recursive).

    > The attached patch touches only em(4) and fxp(4). I will write patches for all
    > other drivers ASAP. But I don't have all the hardware, so if you are using polling(4)
    > and you run FreeBSD 6 or 7, please help me with testing. ATM only em(4) driver patch
    > is tested.

    While you are there, please fix the configuration so that DEVICE_POLLING
    is a normal option. It is very far from being a global option.

    Bruce
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  • Next message: Gavin Atkinson: "vlan(4), bge(4) and bringing parent interface up"

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