Messages in this thread | | | Subject | Re: [PATCH 18 of 38] x86: unify pci iommu setup and allow swiotlb to compile for 32 bit | From | Ian Campbell <> | Date | Wed, 26 Nov 2008 09:36:49 +0000 |
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On Wed, 2008-11-26 at 11:53 +0900, FUJITA Tomonori wrote: > > > + BUG_ON(max_slots > 1UL << (BITS_PER_LONG - IO_TLB_SHIFT)); > > How can this BUG_ON happen? Using u64 for the mask is fine though.
It covers the cases where the previous code would have overflowed. It can't happen right now because although mask is 64 bits the value assigned to it is currently sizeof(unsigned long). If someone changes the type of that field then we would start seeing unexpected values.
Ian.
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