Re: Call for Testers: Convert watchdog spinlock into a sleepable mutex in if_ndis

On Sun, 2008-06-08 at 03:55 +0200, Paul B. Mahol wrote:
> On 6/7/08, Coleman Kane <cokane_at_freebsd.org> wrote:
> > Hi,
> >
> > I've got another patch to if_ndis and I'd like to know if any NDIS users
> > out there can test it for me and give me some feedback. I've converted
> > the ndis_spinlock in if_ndis into a normal sleepable mutex, and would
> > like to get some testers. The idea here is to eliminate an unnecessary
> > "spinning" in the kernel, where it would be preferable to sleep (for CPU
> > usage, interactivity, etc...).
> >
> > You can download it here:
> >       *
> > http://people.freebsd.org/~cokane/patches/if_ndis-spinlock-to-mtx.patch
> >
> > --
> > Coleman Kane
> >
> 
> I did not found any stability regressions in my environment with linked patch.
> 
> But I noticed   new   LOR (it appears as soon as radio of device is turned on):
> 
> lock order reversal:
>  1st 0xc401726c ndis0 (network driver) _at_
> /usr/local/src/sys/modules/if_ndis/../../dev/if_ndis/if_ndis.c:1648
>  2nd 0xc09b3e74 HAL preemption lock (HAL lock) _at_
> /usr/local/src/sys/modules/ndis/../../compat/ndis/subr_hal.c:423
> KDB: stack backtrace:
> db_trace_self_wrapper(c0708534,c3985bcc,c0541a6e,c070adf6,c09b3e74,...)
> at db_trace_self_wrapper+0x26
> kdb_backtrace(c070adf6,c09b3e74,c09b0a51,c09b0a48,c09b09f8,...) at
> kdb_backtrace+0x29
> witness_checkorder(c09b3e74,9,c09b09f8,1a7,c04f7364,...) at
> witness_checkorder+0x6de
> _mtx_lock_flags(c09b3e74,0,c09b09f8,1a7,c457ebd0,...) at _mtx_lock_flags+0xbc
> KfRaiseIrql(2,c457ebd0,c3985c48,c09aacdd,c3d45354,...) at KfRaiseIrql+0x63
> KfAcquireSpinLock(c3d45354,c094888a,c4017200,c3d6cc40,c4017200,...) at
> KfAcquireSpinLock+0x13
> IoQueueWorkItem(c457ebd0,c3d6cc40,0,c4017200,c07040ef,...) at
> IoQueueWorkItem+0x2d
> ndis_tick(c4017200,0,c070699c,166,c077e594,...) at ndis_tick+0x143
> softclock(c077e560,0,c0701ca6,4d4,c3cda6ec,...) at softclock+0x24a
> ithread_loop(c3cdb2e0,c3985d38,c0701a09,324,c3c99a70,...) at ithread_loop+0x1b5
> fork_exit(c04e74f0,c3cdb2e0,c3985d38) at fork_exit+0xb8
> fork_trampoline() at fork_trampoline+0x8
> --- trap 0, eip = 0, esp = 0xc3985d70, ebp = 0 ---

Try this one:
      * http://people.freebsd.org/~cokane/patches/if_ndis-spinlock-to-mtx2.patch

There's the same LOR in the existing code as well, but it is hidden by
WITNESS_SKIPSPIN.

If you can verify that this works, I'll just commit them both as a
single update.

-- 
Coleman Kane