Messages in this thread | | | Date | Sun, 3 Nov 2002 21:18:01 -0800 (PST) | From | "Randy.Dunlap" <> | Subject | Re: interrupt checks for spinlocks |
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On Sun, 3 Nov 2002, Davide Libenzi wrote:
| 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 ...
What's a task in this context? Are we (you) talking about kernel threads/drivers etc. or userspace?
-- ~Randy "I'm a healthy mushroom."
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