Date: Wed, 03 Dec 2014 21:53:20 +0800 From: Julian Elischer <julian@freebsd.org> To: Andriy Gapon <avg@FreeBSD.org>, Warner Losh <imp@bsdimp.com> Cc: freebsd-current@FreeBSD.org Subject: Re: witness and modules. Message-ID: <547F15D0.8050009@freebsd.org> In-Reply-To: <547EF378.8090202@FreeBSD.org> References: <54788FF3.3030602@freebsd.org> <2805430.yZtslRjaC7@ralph.baldwin.cx> <547D4947.4040203@freebsd.org> <F9C776BA-EAF7-4A38-8AEE-3501C41F40D6@bsdimp.com> <547E766A.1070008@freebsd.org> <547EF378.8090202@FreeBSD.org>
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On 12/3/14, 7:26 PM, Andriy Gapon wrote: > On 03/12/2014 04:33, Julian Elischer wrote: >> On 12/3/14, 12:24 AM, Warner Losh wrote: >>>> On Dec 1, 2014, at 10:08 PM, Julian Elischer <julian@freebsd.org> wrote: >>>> >>>> On 12/1/14, 11:39 PM, John Baldwin wrote: >>>>> On Friday, November 28, 2014 11:08:35 PM Julian Elischer wrote: >>>>>> Do we need to compile all modules with witness definitions when >>>>>> linking with a kernel compiled with witness? >>>>>> This was true at one stage but I remember some work was done to make >>>>>> them compatible. >>>>> You should not need this. modules always call functions in the kernel for >>>>> lock operations and this functions are what invoke WITNESS. >>>>> >>>> that's what I thought but empirical evidence disagrees. >>>> I'll try some more cases. >>> I swap back and forth all the time between the two. Kernel modules don’t >>> change when you compile them with WITNESS or without. >> not entirely.. >> hwpmc.ko: U witness_restore >> hwpmc.ko: U witness_save >> zfs.ko: U witness_restore >> zfs.ko: U witness_save > Seems like the problem affects modules that use DROP_GIANT / PICKUP_GIANT. > that's a good observation. I'll take a look a that later.
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