![]() | |||||||||||
Messages in this thread |
Nick Piggin wrote: > On Thursday 21 August 2008 22:26, jmerkey@wolfmountaingroup.com wrote: >> It's simple to reproduce. Take away the volatile declaration for the >> rlock_t structure in mdb-ia32.c (rlock_t debug_lock) in all code >> references and watch the thing lock up in SMP with multiple processors in >> the debugger each stuck with their own local copy of debug_lock. > > You should disable preempt before getting the processor id. Can't see any > other possible bugs, but you should be able to see from the disassembly > pretty easily. debug_lock() is AFAICS only called from contexts which have preemption disabled. Last time around I recommended to Jeff to document this requirement on the calling context. But even though preemption is disabled, debug_lock() is still incorrect as I mentioned in my other post a minute ago. It corrupts its .flags and .count members. (Or maybe it coincidentally doesn't as long as volatile is around.) -- Stefan Richter -=====-==--- =--- =-=-= http://arcgraph.de/sr/ | ||||||||||
| Last update: 2008-08-21 16:13 [from the cache] ©2003-2008 | |||||||||||