Hi Mark, > -----Original Message----- > From: Mark Brown [mailto:[email protected]] > Sent: Friday, June 26, 2015 2:46 PM > To: Gabbasov, Andrew > Cc: [email protected] > Subject: Re: [PATCH] spi: Fix per-page mapping of unaligned vmalloc-ed buffer > > On Thu, Jun 25, 2015 at 11:40:15AM -0500, Andrew Gabbasov wrote: > > spi_map_buf() processes mapping of vmalloc-ed buffers in a special > > way, making mapping of every page separately. However, if the buffer > > is not aligned to page boundary (e.g. sub-array in a vmalloc-ed > > array), it fills the scatter table with page-size unaligned pieces, > > that cross page boundaries. This is incorrect and can, for example, > > cause memory corruption and various crashes when working with ubifs on spi- > nor chips. > > The caller is supposed to be providing us with aligned memory here. > However it could be helpful to do this so...
Well, actually the rest of spi code does not rely on having a transfer buffer page-aligned. And I don't see any reason to make such an assumption here. Especially that it is not fulfilled, at least by ubifs code. Anyway, this fix seems to be useful indeed. > > - const int sgs = DIV_ROUND_UP(len, desc_len); > > + const int sgs = DIV_ROUND_UP(vmalloced_buf ? > > + len + offset_in_page(buf) : len, > > + desc_len); > > No, please write this legibly without the ternery operator. OK, I'll try to make this piece of code more distinct. I'm submitting v2 of the patch. Thanks. Best regards, Andrew -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
