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authorJames Bottomley <jejb@parisc-linux.org>2005-11-17 16:35:09 -0500
committerKyle McMartin <kyle@parisc-linux.org>2005-11-17 16:35:09 -0500
commit08dc2ca61e683e9119ff534dfcd0fd555401fcf7 (patch)
treed891918b735a8896caf1a4cf193125cf01d0e520 /crypto/Kconfig
parent4269b0d371c43bc8f3c9e183847a08258587cf06 (diff)
[PARISC] Fix our spinlock implementation
We actually have two separate bad bugs 1. The read_lock implementation spins with disabled interrupts. This is completely wrong 2. Our spin_lock_irqsave should check to see if interrupts were enabled before the call and re-enable interrupts around the inner spin loop. The problem is that if we spin with interrupts off, we can't receive IPIs. This has resulted in a bug where SMP machines suddenly spit smp_call_function timeout messages and hang. The scenario I've caught is CPU0 does a flush_tlb_all holding the vmlist_lock for write. CPU1 tries a cat of /proc/meminfo which tries to acquire vmlist_lock for read CPU1 is now spinning with interrupts disabled CPU0 tries to execute a smp_call_function to flush the local tlb caches This is now a deadlock because CPU1 is spinning with interrupts disabled and can never receive the IPI Signed-off-by: James Bottomley <jejb@parisc-linux.org> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Diffstat (limited to 'crypto/Kconfig')
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