> There appears to be no kfifo support for iov_iter though, so I just went > with a simple buffer. > > I haven’t looked at the patch too carefully so this is an RFC rather > than an actual patch at this point. It does compile at least. > > Regardless, the more I thin about it, the more I’m under the impression > that the whole rounding up in f_fs was a mistake. And the more I’m > leaning towards ignoring the excess data set by the host. > > ---------- >8 ---------------------------------------------------------- > Subject: usb: gadget: f_fs: buffer data from ‘oversized’ OUT requests > > f_fs rounds up read(2) requests to a multiple of a max packet size > which means that host may provide more data than user has space for. > So far, the excess data has been silently ignored. > > This introduces a buffer for a tail of such requests so that they are > returned on next read instead of being ignored. >
Congratulations finally reach an agreement, thanks Alan Stern and Michal. Here just have a comment - the buffered data need be dropped when the epfile is closed, because it means the session is terminated.
