Messages in this thread | | | Date | Sun, 3 Nov 2002 17:39:29 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: interrupt checks for spinlocks |
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On Sun, 3 Nov 2002, William Lee Irwin III wrote:
> On Sun, 3 Nov 2002, William Lee Irwin III wrote: > [...] > >> The only action taken is printk() and dump_stack(). No arch code has > >> been futzed with to provide irq tainting yet. Looks like a good way > >> to shake out lurking bugs to me (somewhat like may_sleep() etc.). > > On Sun, Nov 03, 2002 at 04:15:46PM -0800, Davide Libenzi wrote: > > Wouldn't it be interesting to keep a ( per task ) list of acquired > > spinlocks to be able to diagnose cross locks in case of stall ? > > ( obviously under CONFIG_DEBUG_SPINLOCK ) > > That would appear to require cycle detection, but it sounds like a > potential breakthrough usage of graph algorithms in the kernel. > (I've always been told graph algorithms would come back to haunt me.) > Or maybe not, deadlock detection has been done before. > > A separate patch/feature/whatever for deadlock detection could do that > nicely, though. What I've presented here is meant only to flag far more > trivial errors with interrupt enablement/disablement than the full > deadlock detection problem.
It's not realy a graph Bill. Each task has a list of acquired locks ( by address ). You keep __LINE__ and __FILE__ with you list items. When there's a deadlock you'll have somewhere :
TSK#N TSK#M ------------- ... ... LCK#I LCK#J ... ... -> LCK#J LCK#I
Then with a SysReq key you dump the list of acquired locks for each task who's spinning for a lock. IMO it might be usefull ...
- Davide
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