On Thu, 13 Mar 2008, FUJITA Tomonori wrote: > > > + for_each_sg(*sgl, sg, nents, i) { > > > > Will there be a problem in subsequent calls if *sgl has been > > incremented but nents hasn't been changed? Maybe nents needs to be a > > pointer also. > > usb_stor_access_xfer_buf doesn't check scsi_sg_count (the number of sg > entries). It assumes that callers take care about the issue. > > If you want nents to be a pointer, I'm fine with it. If nents doesn't change then for_each_sg() won't work right. There could be an alternative macro: /* * Loop over each sg element, stopping at the end of the chain */ #define for_each_sg_all(sglist, sg, __i) \ for (__i = 0, sg = (sglist); sg; __i++, sg = sg_next(sg)) If you added this macro to include/linux/scatterlist.h and used it instead of for_each_sg() then you can get rid of nents entirely. However I'm not sure whether this would be safe. Do people sometimes use a subset of the entries in a scatterlist? If it isn't safe then nents would have to be passed as a pointer too. At this stage I think it would be better to encapsulate sgl, offset, and nents in a single structure than to pass multiple pointers. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html