Messages in this thread | | | Date | Thu, 7 Aug 2008 09:56:10 -0600 (MDT) | Subject | Re: [ANNOUNCE] mdb-2.6.27-rc2-ia32-08-07-08.patch | From | jmerkey@wolfmoun ... |
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> Stefan Richter wrote: >> jmerkey@wolfmountaingroup.com wrote: >>> ftp://ftp.wolfmountaingroup.org/pub/mdb/mdb-2.6.27-rc2-ia32-08-07-08.patch > ... >>> +typedef struct _RLOCK >>> +{ >>> +#if defined(CONFIG_SMP) >>> + spinlock_t lock; >>> +#endif >>> + unsigned long flags; >>> + unsigned long processor; >>> + unsigned long count; >>> +} rlock_t; > ... >> The accessors rspin_lock() and rspin_try_lock() peek into spinlock_t and >> may therefore not be fully portable. Also, they and rspin_unlock() >> don't look SMP safe: > ... >>> + if (rlock->lock.raw_lock.slock && rlock->processor == proc) > > Correction: They _are_ not portable. Look at the first hit in > http://lxr.linux.no/linux+v2.6.26/+code=raw_spinlock_t .
OK. One more to fix. I have to be able to take nested page faults inside the debugger in the event I am debugging a page fault handler or paging event and someone's working set routine crashes.
rspin locks are for these types of cases -- so if I fault on the same processor I took the lock on it just bumps a counter -- yes, it is atomic and SMP safe to do it this way. You are correct that its non-portable but the file this is in is named mdb-IA32 and is not meant as portable to anything other than intel anyway.
As for coding style and misuse of a raw lock structure, I agree with you completely, and I will look for a better way to do this without exposing this structure.
Jeff
> -- > Stefan Richter > -=====-==--- =--- --=== > http://arcgraph.de/sr/ >
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