Alan Stern wrote: > On Sat, 3 Dec 2011, Clemens Ladisch wrote: >> Add a new field num_mapped_sgs to struct urb so that we have a place to >> store the number of mapped entries and can also retain the original >> value of entries in num_sgs. Previously, usb_hcd_map_urb_for_dma() >> would overwrite this with the number of mapped entries, which would >> break dma_unmap_sg() because it requires the original number of entries. >> >> This fixes warnings like the following when using USB storage devices: >> ------------[ cut here ]------------ >> WARNING: at lib/dma-debug.c:902 check_unmap+0x4e4/0x695() >> ehci_hcd 0000:00:12.2: DMA-API: device driver frees DMA sg list with different entry count [map count=4] [unmap count=1] > > Interesting. Do you have any idea why this warning didn't show up > earlier? Is there perhaps a Kconfig option I ought to be using? CONFIG_DMA_API_DEBUG; its help warns of performance degradation. Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
