Eric W. Biederman wrote: > >> revoked_file_ops return 0 from reads (aka EOF). Tell poll the file is > >> always ready for I/O and return -EIO from all other operations. > > > > I think read should return -EIO too. If a program is reading from a > > /proc file (say), and the thing it's reading suddenly disappears, EOF > > gives the false impression that it's read to the end of formatted data > > from that file and it can process the data as if it's complete, which > > is wrong. > > Good point EIO is the current read return value for a removed proc file. > > For closed pipes, and hung up ttys the read return value is 0, and from > my reading that is what bsd returns after a sys_revoke. A few suggestions below. Feel free to ignore them on account of the basic revoking functionality being more important :-) I'm not sure a revoked pipe should look like a normally closed one. ECONNRESET? For hung up ttys, I agree. But where's the SIGHUP :-) You probably do want the process using it to die if it's not handling SIGHUP, because terminal-using processes don't always terminate themselves on EOF. For things writing to a pipe or file, SIGPIPE may be appropriate in addition to EIO, to avoid runaway processes. Looks odd I know. For writing to a terminal, SIGHUP again. > The reason I have f_op settable is because I never expected complete > agreement on the return codes, and because it makes auditing and spotting > this kind of thing easier. > > I guess I should make two variations on revoked_file_ops then. Say > eof_file_ops, eio_file_ops. Identical except for their treatment of > reads. Fair enough. It's good to have good defaults. I'm not convinced eof_file_ops is ever a good default. sighup_file_ops and sigpipe_file_ops maybe :-) -- Jamie -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
