Messages in this thread |  | | From | Andi Kleen <> | Subject | Re: [patch] i386/x86_64: smp_call_function locking inconsistency | Date | Fri, 9 Feb 2007 08:40:12 +0100 |
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On Thursday 08 February 2007 21:32, Heiko Carstens wrote: > On i386/x86_64 smp_call_function_single() takes call_lock with > spin_lock_bh(). To me this would imply that it is legal to call > smp_call_function_single() from softirq context. > It's not since smp_call_function() takes call_lock with just > spin_lock(). We can easily deadlock: > > -> [process context] > -> smp_call_function() > -> spin_lock(&call_lock) > -> IRQ -> do_softirq -> tasklet > -> [softirq context] > -> smp_call_function_single() > -> spin_lock_bh(&call_lock) > -> dead > > So either all spin_lock_bh's should be converted to spin_lock, > which would limit smp_call_function()/smp_call_function_single() > to process context & irqs enabled. > Or the spin_lock's could be converted to spin_lock_bh which would > make it possible to call these two functions even if in softirq > context. AFAICS this should be safe.
I'm not so sure. Perhaps drop _bh in both and stick a WARN_ON_ONCE in to catch the cases?
-Andi
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