Re: witness and modules.
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 jul...@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. -- Andriy Gapon ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
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 jul...@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. ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
On Wednesday, December 03, 2014 09:53:20 PM Julian Elischer wrote: 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 jul...@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. Yes, that isn't really intended to be used publically. The pmc one is stale as system calls haven't run with Giant in several releases. All the ones for g_topology_lock() also seem to be broken-by-designed. There is no good reason I can think of for g_topology_lock() to assert that Giant isn't held. I suspect phk@ just wanted to force geom to be locked without Giant, but I'm not sure that is the best way to achieve that? Poul, is that correct? If you fix that you can remove almost all of the DROP_GIANT/PICKUP_GIANT in the tree. They should really only be in the _sleep() and cv_wait_*() functions where they are used to give Giant its special property of being dropped while asleep. -- John Baldwin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
On Dec 1, 2014, at 10:08 PM, Julian Elischer jul...@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. Warner signature.asc Description: Message signed with OpenPGP using GPGMail
Re: witness and modules.
On 12/3/14, 12:24 AM, Warner Losh wrote: On Dec 1, 2014, at 10:08 PM, Julian Elischer jul...@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. Warner it's a 10.0 based system. the zfs kernel module grew a reference to witness_restore and witness_save when it was compiled with witness in opt_global.h. I certainly wouldn't load with a standard kernel. it may have been somethign funny with the zfs compat layer stuff, and I'm pretty sure people don't use zfs as a module much, but it was definitely there. note: it'd probably work the other way around.. a non-witness module would probably load on a witness kernel.. none of the other kernel modules had that extra reference so I think it's specific to zfs. Maybe to the way it was compiled.. the sources are pretty standard but the makefiles are a bit hacked.. ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
On 12/3/14, 12:24 AM, Warner Losh wrote: On Dec 1, 2014, at 10:08 PM, Julian Elischer jul...@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 Warner ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
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. -- John Baldwin ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
Re: witness and modules.
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. ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
witness and modules.
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. ___ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to freebsd-current-unsubscr...@freebsd.org
HEADSUP: WITNESS adn modules == bad juju
Boris reminded me of someething I had forgotten to mention: currently unloading a module that uses mutexes with WITNESS enabled in the kernel will panic the kernel, cause witness tries to look at the string of the mutex name which is usually a constant in the module later on. This leads to a kernel page fault basically, so until I get this fixed, you really can't unload modules with WITNESS right now. -- John Baldwin [EMAIL PROTECTED] -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
