Re: [PATCH] OsdSynch.c modernization

2007/9/22, Jung-uk Kim <jkim_at_freebsd.org>:
> I thought exactly the same when I started rewriting it (almost half
> year ago!).  I have tried all of the above, spent numerous sleepless
> nights, and miserably failed. :-(
>
> Spin mutex is too restrictive (e.g., it cannot be used with other
> locks gracefully).  critical_enter() causes:
>
> panic: blockable sleep lock (sleep mutex) 32 _at_
> /usr/src/sys/vm/uma_core.c:1830 cpuid = 0
> KDB: enter: panic
> [thread pid 21 tid 100013 ]
> Stopped at      kdb_enter+0x32: leave

However, disabling interrupts while you block on other locks is just as bad, 
we just don't assert for it.  Better would be to fix ACPI-CA to not try to 
malloc() while holding a spin lock.  You should be able to see where it is 
doing that via the stack trace.  If the malloc is using M_NOWAIT you will be 
far better off using a plain mutex and just not disabling interrupts.

-- 
John Baldwin