| Message ID | 20190111181731.11782-3-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/3] dma-mapping: remove the default map_resource implementation | expand |
On 11/01/2019 18:17, Christoph Hellwig wrote: > Use WARN_ON_ONCE to print a stack trace and return a proper error > code instead. I was racking my brain to remember the reasoning behind BUG_ON() being the only viable way to prevent errors getting through unhandled, but of course that was before we had a standardised DMA_MAPPING_ERROR that would work across all implementations. > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > include/linux/dma-mapping.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index d3087829a6df..91add0751aa5 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -353,7 +353,8 @@ static inline dma_addr_t dma_map_resource(struct device *dev, > BUG_ON(!valid_dma_direction(dir)); > > /* Don't allow RAM to be mapped */ Ugh, I'm pretty sure that that "pfn_valid means RAM" misunderstanding originally came from me - it might be nice to have a less-misleading comment here, but off-hand I can't think of a succinct way to say "only for 'DMA' access to MMIO registers/SRAMs/etc. and not for anything the kernel knows as actual system/device memory" to better explain the WARN... Either way, though, Reviewed-by: Robin Murphy <robin.murphy@arm.com> > - BUG_ON(pfn_valid(PHYS_PFN(phys_addr))); > + if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) > + return DMA_MAPPING_ERROR; > > if (dma_is_direct(ops)) > addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs); >
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index d3087829a6df..91add0751aa5 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -353,7 +353,8 @@ static inline dma_addr_t dma_map_resource(struct device *dev, BUG_ON(!valid_dma_direction(dir)); /* Don't allow RAM to be mapped */ - BUG_ON(pfn_valid(PHYS_PFN(phys_addr))); + if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) + return DMA_MAPPING_ERROR; if (dma_is_direct(ops)) addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs);
Use WARN_ON_ONCE to print a stack trace and return a proper error code instead. Signed-off-by: Christoph Hellwig <hch@lst.de> --- include/linux/dma-mapping.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)